Focus on: All days Jun 15, 2014 Jun 16, 2014 Jun 17, 2014 Jun 18, 2014 Jun 19, 2014 Jun 20, 2014 All sessions "Friends of CAP" Dinner and Meeting / Souper... (F-PLEN1) - CAP Best Student Presentations... (F-PLEN2) Plenary Session - Jack Cunningham,... (F-PLEN3) Announcement of Winner, CAP Best... (F1-1) Pattern Formation and Statistical... (F1-2) History of Physics - DHP / Histoire de... (F1-3) Future of Cosmic Frontier: Cosmolgy -... (F1-4) Nuclear Safety -DNP-DIAP / Sureté... (F1-5) Future of Cosmic Frontier: Dark Matter... (F1-6) Atomic, Molecular and Optical Physics -... (M-HERZ) Herzberg Memorial Public Lecture -... (M-PLEN-1) Plenary Session - Start of... (M1-1) Topological States of Matter - DCMMP /... (M1-2) ePOP satellite mission I - DASP /... (M1-3) Medical Imaging I - DMBP / Imagerie... (M1-4) Energy Frontier: Standard Model and... (M1-5) Quantum Gravity and Quantum Cosmology -... (M1-6) Testing Fundamental Symmetries I -... (M1-7) Ultrafast Imaging and Spectroscopy I -... (M2-1) ePOP Satellite Mission II - DASP /... (M2-10) Testing Fundamental Symmetries II -... (M2-2) Nuclear Astrophysics - DNP / ... (M2-3) Advances in PP and NP Theory -... (M2-4) Neutrinos Long Baseline PPD-DNP /... (M2-5) Magnetic / Frustrated Systems - DCMMP /... (M2-6) Radiation Therapy - DMBP / Thérapie par... (M2-7) Ultrafast Imaging and Spectroscopy II -... (M2-8) Teaching Physics to a Wider Audience -... (M2-9) Status and Future of Precision Frontier... (R-MEDAL) CAP Medal Talk - David London, U. de... (R-PLEN) Plenary Session - Jim Chelikowsky, U.... (R1-1) Interactive Teaching/Teaching with... (R1-10) Cosmic Frontier: Cosmology - PPD-DTP /... (R1-11) Biomolecules, Cells, and Beyond -... (R1-2) Plasmonics - DAMOPC-DCMMP / Plasmonique... (R1-3) Ion Beam Analysis and Modification -... (R1-4) Biophysics/Soft Condensed Matter V -... (R1-5) Computational Materials Mini-symposium... (R1-6) Quantum Information Theory -... (R1-7) Hadronic Structure - DNP / Structure... (R1-8) Mathematical Physics - DTP / Physique... (R1-9) Future of Cosmic Frontier: Dark Matter... (R2-1) Erich Vogt Memorial Session I -... (R2-2) Curriculum Development and... (R2-3) Biophysics/Soft Condensed Matter VI -... (R2-4) Computational Materials Mini-symposium... (R2-5) Industrial and Applied Physics - DIAP /... (R2-6) Quantum Entanglement and Computational... (R3-1) Erich Vogt Memorial Session II -... (R3-2) Biophotonics II - DAMOPC-DIAP /... (R3-3) Computational Materials Mini-symposium... (T-MEDAL1) CAP Medal Talk - Ian Affleck, UBC... (T-MEDAL2) CAP Medal Talk - Melanie Campbell,... (T-MEDAL3) CAP Medal Talk - Mark van... (T1-1) Energy Frontier: Higgs Properties -... (T1-2) Testing Fundamental Symmetries III -... (T1-3) Relativity and Gravitation - DTP /... (T1-4) Mass Spectrometry and Nuclear Structure... (T1-5) What we can do to help our students... (T1-6) Quantum Optics - DAMOPC / Optique... (T1-7) Quantum Materials - DCMMP / Matériaux... (T1-8) Surfaces and Thin Films - DCMMP-DSS /... (T1-9) Medical Imaging II - DMBP / Imagerie... (T2-1) Theoretical Astrophysics - DTP /... (T2-10) Neutrinoless Double Beta Decay -... (T2-2) Nuclear Physics, Heavy Ions, Extreme... (T2-3) Energy Frontier: Supersymmetry -... (T2-4) Gender and Arts in Physics Teaching -... (T2-5) Biophotonics I - DAMOPC-DIAP /... (T2-6) Biophysics/Soft Condensed Matter I:... (T2-7) Superconducting Materials - DCMMP /... (T2-8) Plasma Physics and Applications - DPP /... (T2-9) Instrumentation - DIMP / Instrumentation - DPIM (T3-1) Atmospheric and Space Physics - DASP /... (T3-2) Panel Discussion: Gender Equality -... (T3-3) Cavity QED and Optomechanics -... (T3-4) Novel Light and Particle Sources -... (T3-5) Biophysics/Soft Condensed Matter II:... (T3-6) Control of dynamical properties- DCMMP... (T3-7) Cosmology - DTP / Cosmologie - DPT (T3-8) Searches for Higgs in the Standard... (T3-9) Neutrinos: Underground and Future - DTP... (W-MEDAL1) CAP Medal Talk - Matt Dobbs, McGill... (W-MEDAL2) CAP Medal Talk - André-Marie... (W-PLEN1) Plenary Session - Gabriela Gonzalez,... (W-Pub) CAP Commercial Publishers' Session /... (W1-1) Experimental Advances and Acccelerators... (W1-2) 100 Years of X-ray Diffraction -... (W1-3) Condensed Matter Theory - DTP-DCMMP /... (W1-4) Fields and Strings - DTP / Champs et... (W1-5) Biophysics/Soft Condensed Matter III:... (W1-6) Cold Atoms and Molecules - DAMOPC-DCMMP... (W1-7) Cosmic Frontier: Dark Matter - PPD /... (W1-8) Energy Frontier: Exotics - PPD-DTP /... (W2-1) Low Dimensional Systems - DCMMP /... (W2-2) Photovoltaic and optical materials -... (W2-3) THz science and applications DAMOPC /... (W2-4) Biophysics/Soft Condensed Matter IV:... (W2-5) Heavy Mesons and QCD - DTP-DNP / Mésons... (W2-6) Gravitational Waves and Gravitational... (W2-7) Future of Cosmic Frontier: Dark Matter... (W2-8) Energy Frontier: ATLAS at ~14 TeV -... (W2-9) Molecular Biophysics - DMBP /... Banquet and after dinner speaker (David... Banquet Reception / Réception du banquet Board Meeting for IPP / Réunion du Conseil de l'IPP CAP Annual General Meeting / Assemblée... CAP Council (Old and New) / Conseil de l'ACP... CAP Council Meeting (New and Old) / Réunion du... CAP Executive (New and Old) Breakfast Meeting... CAP Foundation Annual General Meeting /... CAP Foundation Board Meeting / Réunion du c.a.... CAP Past Presidents' Lunch / Dîner des anciens... CAP President's report / Rapport du président de l'ACP CAP Teachers Workshop (Day 2) with SNOLAB Tour... CAP Teachers Workshop (Day I) / Atelier des... CAP-NSERC Liaison Committee Meeting / Réunion... CAP-NSERC Liaison Committee Report (J.... CAP/LOC co-chairs meeting / Réunion... CEWIP Annual Meeting & Reception / Assemblée... CINP Annual General Meeting / Assemblée... CINP Board Meeting / Réunion du Conseil de l'ICPN CJP Editorial Board Meeting / Réunion du... CNILC Breakfast Meeting / Réunion du comité de... DAMOPC Annual Meeting / Assemblée annuelle DPAMC DAMOPC Poster Session with beer (6) / Session... DASP Poster Session, with beer (1) / Session... DCMMP Annual Meeting / Assemblée annuelle DPMCM DCMMP Poster Session, with beer (4) / Session... DHP Annual Meeting / Assemblée annuelle DHP DIAP Annual Meeting / Assemblée annuelle DPIA DIMP Annual Meeting / Assemblée annuelle DPIM DMBP Annual Meeting / Assemblée annuelle DPMB DNP Annual Meeting / Assemblée annuelle DPN DPE Annual Meetings / Assemblée annuelle DEP DPP Annual Meeting / Assemblée annuelle DPP DTP Annual Meeting / Assemblée annuelle DPT DTP Poster Session, with beer (2) / Session... Exhibit booths open 08:30-15:15 / Salle... Exhibit booths open 08:30-17:30 / Salle... Exhibit booths open 08:30-17:30 / Salle... Heads/Chairs Business Meeting / Réunion des... Health Break (with exhibitors) / Pause santé... Health Break (with exhibitors) / Pause santé... Health Break (with exhibitors) / Pause santé... Health Break (with exhibitors) / Pause santé... Health Break (with exhibitors) / Pause santé... Health Break / Pause santé Health Break / Pause santé Health Break / Pause santé Health Break / Pause santé Health Break / Pause santé IPP Annual General Meeting (cont'd) /... IPP Annual General Meeting / Town Hall Joint CINP-IPP Reports from NSERC, SNOLAB and... Lunch / Dîner Lunch / Dîner Lunch / Dîner Meeting of CAP Executive (Old and New) /... New Faculty Lunch Meeting with NSERC /... NSERC EG Chair Report (L.-H. Xu) / Rapport de... NSERC Presentation by Elizabeth Boston /... Outreach "Tête-à-tête Liaisons externes PiC Editorial Board Meeting / Réunion du... PPD Annual Meeting / Assemblée annuelle PPD PPD Poster Session, with beer (7) / Session... Professional Development Progressive Dinner at Science North Museum Science Policy Committee Breakfast Meeting /... Welcome BBQ Reception / Réception d'accueil avec BBQ Hide Contributions
America/Toronto English (United States)
2014 CAP Congress / Congrès de l'ACP 2014
Jun 15, 2014, 8:00 AM → Jun 20, 2014, 6:00 PM America/Toronto
Laurentian University / Université Laurentienne
CHANGES TO PROGRAM AS AT JUNE 13 (CHANGEMENTS AU PROGRAMME)
GENERAL INFORMATION - PLEASE READ
INFORMATION GÉNÉRALE - VEUILLEZ LIRE
CLICK ON "TIMETABLE" IN THE MENU ON THE LEFT TO VIEW THE ONLINE PROGRAM.
The 2014 CAP Congress is being hosted by Laurentian University, June 16-20, 2014. This Congress will be an opportunity to showcase and celebrate the achievements of physicists in Canada and abroad. Mark your calendars and bookmark the main Congress web site at http://www.cap.ca/en/congress/2014 for easy access to updates and program information.
CLIQUEZ SUR "TIMETABLE" DANS LE MENU À GAUCHE POUR VOIR LA PROGRAMMATION EN LIGNE.
Le Congrès 2014 de l'ACP se tiendra à l'Université Laurentienne du 16 au 20 juin 2014. Au cours de cet événement nous pourrons profiter des présentations et des réalisations de physiciens et physiciennes du Canada et d'ailleurs, et les célébrer. Inscrivez la date du congrès à votre agenda et créez un signet de l'adresse du site web du congrès (http://www.cap.ca/fr/congres/2014) pour accéder facilement aux mises à jour et au contenu de la programmation.
2014 CAP Congress Poster
indico-support@cern.ch
Sat, Jun 14
Sun, Jun 15
Mon, Jun 16
Tue, Jun 17
Wed, Jun 18
Thu, Jun 19
8:00 AM → 12:30 PM
Meeting of CAP Executive (Old and New) / Réunion de l'exécutif (ancien et nouveau) Room B (Holiday Inn)
Room B
CAP Council (Old and New) / Conseil de l'ACP (ancien et nouveau) Room B (Holiday Inn)
IPP Annual General Meeting / Town Hall Georgian D&E (Holiday Inn; Remote Call in: 1-888-289-4573; Access code: 1129370)
Georgian D&E
Holiday Inn; Remote Call in: 1-888-289-4573; Access code: 1129370
Convener: Michael Roney (University of Victoria)
Introduction 10m
Speaker: Michael Roney (University of Victoria)
Compute Canada-Upcoming Competition 15m
Speaker: Dugan O'Neil (SFU Simon Fraser University (CA))
News From CINP and Interest in Joint CREATE Grant 20m
Speaker: Garth Huber (University of Regina)
SNO+ 20m
Speaker: Chen Mark (Queen's University)
SuperCDMS 20m
Speaker: Wolfgang Rau
Belle II 20m
Speaker: Steven Robertson (McGill)
ATLAS 20m
Speaker: Richard Teuscher (University of Toronto (CA))
BREAK 15m
EXO-WIPP 20m
Speaker: Kevin graham
VERITAS 20m
Speaker: David Hanna (McGill University)
BaBar 10m
Speaker: Christopher Hearty (University of British Columbia)
PiENu 10m
Speaker: Douglas Bryman (U)
HEPNET 10m
Speaker: Randy Sobie (University of Victoria (CA))
PICASSO-PICO 20m
Speaker: Carsten Krauss (U)
T2K 20m
Speaker: Hirohisa A. Tanaka (University of British Columbia)
DEAP 20m
Speaker: Mark Boulay (Queen's University)
7:30 PM → 10:00 PM
Board Meeting for IPP / Réunion du Conseil de l'IPP Georgian D & E (Holiday Inn)
Georgian D & E
CINP Board Meeting / Réunion du Conseil de l'ICPN Room 251 (Holiday Inn)
Convener: Prof. Garth Huber (University of Regina)
Joint CINP-IPP Reports from NSERC, SNOLAB and TRIUMF (DNP-PPD) / Rapports conjoints ICPN-IPP du CRSNG, SNOLAB et TRIUMF (DPN-PPD): DPN-PPD A-226
Conveners: Prof. Garth Huber (University of Regina), Michael Roney (University of Victoria)
NSERC SAP ES Chair's Report 40m
TRIUMF Scientific Director Report 40m
Speaker: Prof. Reiner Kruecken (TRIUMF)
SNOLAB Director's Report 20m
Speaker: Nigel Smith (SNOLab)
PiC Editorial Board Meeting / Réunion du Comité de rédaction de La Physique au Canada F-336
Convener: Bela Joos (University of Ottawa)
Health Break / Pause santé
CINP Annual General Meeting / Assemblée générale annuelle de l'ICPN C-304
10:30 AM → 1:00 PM
IPP Annual General Meeting (cont'd) / Assemblée générale annuelle de l'IPP (suite) A-226 (Laurentian University / Université Laurentienne; Remote Access: 1-888-289-4573; Code: 1129370)
Laurentian University / Université Laurentienne; Remote Access: 1-888-289-4573; Code: 1129370
IPP Director's Report & Council Election Results 20m
ALPHA 15m
Speaker: Makoto Fujiwara (TRIUMF (CA))
The Moller Experiment - JLAB 15m
Speaker: Michael Gericke (University of Manitoba)
HALO 10m
Speaker: Clarence Virtue (Laurentian University)
ICECUBE 15m
Speaker: Darren Grant (University of Alberta)
Review of Canadian Theory Activities 20m
Speaker: Itay Yavin (New-York University)
Potential Roles of IPP to Support of Theory Community 10m
Speaker: David Morrissey (TRIUMF)
Use of Potential CREATE Grant to Suppprt IPP Community 20m
Speaker: Adam Ritz (University of Victoria)
Discussion: IPP Priorities and Inititatives - Summary 20m
(M-PLEN-1) Plenary Session - Start of Conference - Nigel Smith, SNOLAB / Session plénière - Ouverture du Congrès - Nigel Smith, SNOLAB FA-054+5+6
FA-054+5+6
Deep Underground Physics: the SNOLAB Science Programme 45m
The field of astroparticle physics studies many of the major outstanding questions in contemporary astro-particle and sub-atomic physics, through the study of naturally created particles within the Universe. These questions range from "what makes up most of the Universe", through "what accelerates the most energetic particles in the Universe" to "why are we here at all?" These studies are undertaken by deploying extremely sensitive particle detectors into various environments, often extreme and challenging, to provide the required conditions to search for rare events, faint signals or weak interactions. The SNOLAB astroparticle physics research facility based 2km underground at the Vale Creighton nickel mine has been developed from the initial successful SNO project to host a new programme of experiments. These experiments focus primarily on sub-atomic physics, with studies of supernova and low energy solar neutrinos, neutrino-less double beta decay and Galactic dark matter searches. These all require the quiet radiation environment that SNOLAB affords, due to the reduction in cosmic rays activity and clean-room operation of the facility. This talk will outline the initial science programme that is being conducted at SNOLAB, detailing some of the first projects that have been deployed. The status of the facility itself will be discussed, illustrating the purpose and requirements for a deep underground laboratory, and a brief review of the global situation in underground physics will be given.
(M1-1) Topological States of Matter - DCMMP / États topologiques de la matière - DPMCM A-226
Convener: Steve Dodge (Simon Fraser University)
Spin-orbit coupling + Interaction = ? 30m
Strongly interacting electron systems have fascinated the condensed matter community for a few decades. The addition of interactions to a model leads, in many cases, to new kinds of states, especially in low dimensional systems where fluctuations are pronounced. Notable examples are unconventional superconductivity and the fractional quantum Hall effect. Spin orbit coupling, on the other hand, has been in the spotlight in recent years due to its important role in topological insulators and superconductors. It is responsible to the non-trivial topology of topological insulators in two and three dimensions. It is therefore tempting to ask what is the combined effect of electron-electron interactions and spin orbit coupling. In this talk I will discuss several models which include these two ingredients. The resulting behaviour ranges from incommensurate spin density wave to a strongly correlated topological superconductor. I will discuss the challenges of characterizing these topological many body states.
Speaker: Prof. Tami Pereg-Barnea (McGill University)
Topological insulators: interaction effects and new states of matter 30m
Topological insulators are recently discovered states of matter that are electrically insulating in the bulk but support novel conducting boundary states that are exceptionally robust to perturbations. The physics of topological insulators is due to strong spin-orbit coupling and, despite its exotic character, is well understood in a single-particle picture where electron-electron interactions are neglected. A topic of tremendous current interest in the field is to understand how the physics of topological insulators is affected by the presence of substantial electron-electron interactions. In this talk I will argue that the combination of a topological bandstructure and strong electron-electron interactions can give rise to novel phenomena that have no counterpart in either noninteracting topological systems or nontopological interacting systems.
Speaker: Dr Joseph Maciejko (Princeton University)
Phonon-induced topological insulation 30m
Recent years have witnessed the unexpected discovery of novel topological phases in certain electrically insulating and semimetallic solids whose low-energy bulk excitations are Dirac fermions. Topological phases in these ''Dirac materials'' are characterized by nonzero integers (topological invariants), which manifest themselves through peculiar and robustly gapless states localized at the boundaries of the material. Partly enticed by a vision of transistors that would operate by switching topological invariants on and off, there is keen interest in finding ways to induce topological phases in intrinsically nontopological materials. In this talk, I will show that electron-phonon interactions can alter the band topology of narrow-gap Dirac insulators and semimetals, at both zero and nonzero temperature. The underlying mechanism for this effect can be explained in terms of the electron-phonon scattering matrix elements, which show a peculiar dependence on the sign of the mass of the Dirac fermions. Contrary to the common belief that increasing temperature always destabilizes topological phases, our results highlight instances in which phonons might lead to the appearance of topological surface states above a crossover temperature in a material that has a topologically trivial ground state. I will discuss possible experimental implications of this effect in HgTe/CdTe quantum wells and in Bi Tl(S_x Se_{1-x})_2.
Speaker: Prof. Ion Garate (Université de Sherbrooke)
(M1-2) ePOP satellite mission I - DASP / Mission satellitaire ePOP I - DPAE C-205
Convener: Robert Rankin (U)
Probing the Ionosphere with the Radioscience Instruments on CASSIOPE/e-POP 30m
Two major themes in the ePOP ionospheric radioscience plan are the structure and dynamics of the three-dimensional distribution of density and plasma-wave processes. The e-POP wave instruments involved are the GPS Attitude, Position and Profiling (GAP) instrument, the Coherent Electromagnetic Radiation Tomography (CERTO) beacon, and the Radio Receiver Instrument (RRI) The e-POP radioscience agenda exploits opportunities for observations coordinated both with other instruments aboard CASSIOPE and with ground observatories and other ionosphere-thermosphere spacecraft. The GAP receives signals from the Global Positioning System (GPS) satellites for studies of ionospheric structure. When combined with data from earth-based GPS receivers, these measurements are used to improve ionospheric tomography. CERTO transmits at VHF and UHF for detection by dedicated receivers on the ground, for similar purposes of two- or three-dimensional imaging of density structure and for investigation of scattering by ionospheric irregularities. RRI is a four-channel digital receiver for recording the electric fields of waves between 10 Hz and 18 MHz. Collaborative studies using transionospheric HF propagation are under way for imaging mesoscale structures near the peak of the F-region, through the reception of waves from ionosondes, coherent backscatter radars or other HF transmitters. The structure thus observed can be compared with the results of ionospheric tomography from CERTO and GAP. Electromagnetic phenomena of spontaneous origin are investigated in collaborations involving the RRI and ground-based receivers of space emissions. Propagation at frequencies from ELF to HF are studied to understand access to the magnetosphere of manmade signals and access to the ground of spontaneous noise from space.
Speaker: Dr Gordon James (CSA David Florida Laboratory)
Back to the Ionosphere 50 Years Later: the CASSIOPE Enhanced Polar Outflow Probe (e-POP) 30m
The launch of the Alouette I satellite on September 29, 1962, marked Canada's entry into the space age. The successful launch on the CASSIOPE small satellite fifty-one years later to the day marks Canada's return to the ionosphere. CASSIOPE carries two payloads: the Enhanced Polar Outflow Probe (e-POP), an 8-instrument scientific payload, and CASCADE, a communications technology demonstration payload. The e-POP instrument suite is comprised of plasma, magnetic field, radio, and optical instruments designed for in-situ observations in the topside polar ionosphere at the highest-possible resolution, and it utilizes CASCADE for onboard data storage and telemetry downlink - to help demonstrate the capabilities of CASCADE. In this paper, we present an overview of the e-POP payload and its scientific objectives, and selected examples of initial results from the early part of the CASSIOPE mission.
Speaker: Prof. Andrew Yau (University of Calgary)
Science Objectives and Results from the ePOP Suprathermal Electron Imager 30m
The ePOP Suprathermal Electron/Thermal Ion Imager (SEI/SII) uses a microchannel-plate-intensified CCD-based detector to record 2-D (energy/angle) electron distribution functions having a nominal energy range of 2-200 eV, and ion distributions at energies that include the ambient ionospheric population ($<1$ eV) and extending up to 100 eV. At the highest measurement resolution, distribution images are 64 pixels in diameter, read out at a rate of 100 per second. The SEI is designed to address one of the principal scientific objectives of ePOP, namely to characterize polar ion outflow and its drivers including ambipolar electric fields generated by suprathermal electron populations, and direct heating of ions by plasma waves or collisions with neutral particles. In SII mode the instrument can track ion velocity in two dimensions, and can characterize ion temperature and higher-order properties of the distribution. This talk presents highlights of the first half year of ePOP SEI operations.
Speaker: Prof. David Knudsen (University of Calgary)
(M1-3) Medical Imaging I - DMBP / Imagerie médicale I - DPMB C-204
Convener: Robert LeClair (Laurentian University)
The Potential of Polariszation Imaging of the Eye to Provide a Window on the Brain in Alzheimer's Disease and Malaria 15m
Imaging the retina may provide a "window on the brain", potentially enabling diagnosis of neural conditions. Two of these are malaria and Alzheimer's disease (AD). AD is a neuro-degenerative disease, characterized by the formation of insoluble fibrils (plaques) composed of amyloid beta proteins. There is currently no definitive diagnosis available prior to death. Neurotoxic effects of amyloid beta have been demonstrated in the retinas of animal models and human retinal function is affected by AD. Previously, our group was among the first to find amyloid beta in the retinas of those diagnosed with AD and we have demonstrated that polarization imaging could improve the visibility of malaria in retinal vessels. Here we will describe the development of non-invasive imaging methods that might be used for *in vivo* diagnosis of both conditions. Imaging in the human retina in both malaria and Alzheimer's disease (AD) could lead to a better understanding of the diseases and earlier and more accessible diagnoses. Whole mounts were prepared of post-mortem retinas of subjects with AD and malaria and of age matched subjects without disease. In the AD study, retinas were stained with thioflavin S and examined using a fluorescence microscope. Previously, in some retinas, positive for AD, fluorescently labeled structures near the retinal surface were studied using Atomic Force Microscopy. The polarization properties of the *ex vivo* retinas were imaged under crossed polarizers along with the surrounding retina. In addition, spatially defined Mueller matrices were found by imaging in a microscope modified with an adjustable polarization generator and an analyzer. We have confirmed the presence of amyloid beta in the *ex vivo* neural retina of those with AD and not in age matched normal donors without the disease with sensitivity and specificity each at 75%. The polarization properties of amyloid beta deposits differed significantly from those of bare glass from the surrounding retinal tissue and from control retinas. Ours are the first measurements of the polarization properties of unstained amyloid beta. We believe that the *in vivo* imaging methods that we are developing could become a more accessible, less invasive and less expensive technique than others under development for the diagnosis of malaria affecting the brain and Alzheimer's disease.
Speaker: Prof. Melanie C.W. Campbell (Physics and Atronomy, School of Optometry and Guelph Waterloo Physics Institute, University of Waterloo)
Wide angle x-ray scatter models in breast diagnostics 30m
In our group we are devising wide angle x-ray scatter (WAXS) models for breast diagnostic applications. A major focus is to use the models in conjunction with energy dispersive x-ray scatter measurements on breast biopsies. A custom built WAXS system has been assembled and it provides quantitative differential linear scatter coefficients (MUs) to be obtained for samples. Comparison between fibrous and cancerous breast samples showed differences but results were not consistent. The fat content in the biopsies could have affected the results. A method to correct for the presence of fat has been formulated and tested with breast phantom materials. A digital x-ray imaging method provides estimates of the fractional volume of fat νf in the biopsies. The protocol for analysis is first to measure the MUs of the composite sample in the WAXS system, then estimate νf of the sample via an x-ray imaging analysis in another system. Once νf is known, a WAXS fat subtraction model using νf is applied to estimate the MUs of fatless tissue. Consider a chicken composite consisting of fibrous and tissue components. The νf within an ROI of the sample was estimated to be 0.32±0.05. The subtraction of this component from the WAXS composite signal provided a good estimate of the MUs of chicken fibrous. The results were encouraging and analysis of breast biopsies is to re-commence. The WAXS models are also being investigated for their potential use in CBCT breast imaging. The models can be used to correct for scatter. The scatter projection obtained via the WAXS model was subtracted from a GEANT4 projection to yield an estimation of the energy incident signal from primary photons. For a 14 cm diameter cylindrical 50:50 fat/fibrous phantom the estimation was 1.017 ± 0.012 relative to the GEANT4 output.
Speaker: Prof. R. J. LeClair (Laurentian University)
An energy dispersive bent Laue monochromator for K-edge subtraction imaging 15m
K-Edge Subtraction (KES) is a powerful synchrotron imaging method that allows the quantifiable determination of a contrast element (i.e. iodine) and matrix material (usually represented as water) in both projection imaging and computed tomography. With living systems, a bent Laue monochromator is typically employed to prepare imaging beams above and below the contrast element K-edge which focus at the subject location and subsequently diverge onto a detector. Conventional KES prepares the two beams by utilizing a splitter that blocks approximately 1/3 of the vertical beam size to prevent "edge crossing" energies beyond the monochromator. A bent Laue monochromator has been developed that has very good focal and energy dispersive properties for KES. Approximately 4% of the vertical beam profile is involved in "edge crossing" energies, thus no splitter is employed. The beam can be narrowed vertically allowing a smaller crossover angle than a splitter based system which minimizes artifacts. The combination of good spatial resolution, energy dispersive properties, flux and a unique approach to data analysis make this system nearly ideal for KES. Some of the relevant details of the monochromator will be discussed, especially the focal and energy dispersive properties, as well as, some details of artifacts caused by the beam focusing at the sample location. Example images of the beam and the object images will be presented as well.
Speaker: Nazanin Samadi (U)
A New Software for Image Registration in Multimodality, PET-MR, Imaging in Cell Tracking Studies 15m
Positron emission tomography (PET) is an essential tool for in vivo molecular imaging, due to its high sensitivity. Combined with the unparalleled soft tissue contrast of magnetic resonance imaging (MRI), PET–MRI allows for accurate quantification required for cell tracking studies. The purpose of this study is to develop a landmark based image registration program capable of fiducial registration, for application in a stem cell tracking study . PET and MR Images acquired with fiducial markers located in the field of view around the specimen were registered using our landmark based program, written in Matlab. The fiducial markers were also used to test the accuracy of our Matlab program, along with other automated image registration software including: automatic image registration (AIR), FMRIB's linear image registration tool (FLIRT), and medical image processing, analysis, and visualization (MIPAV), all available online free for download. All of the programs were able to successfully register the images; however, our Matlab program provided the best registration accuracy, with a fiducial registration error (FRE) of 1.36 mm.
Speaker: Esmat Elhami (U)
(M1-4) Energy Frontier: Standard Model and Higgs - PPD / Frontière d'énergie: modèle standard et boson de Higgs - PPD C-112
Convener: Oliver Stelzer-Chilton (TRIUMF (CA))
Standard Model Measurements with the ATLAS Detector 30m
The ATLAS experiment at the Large Hadron Collider includes a large program of Standard Model measurements covering a wide range of interactions and final state topologies including jets, charged leptons, and photons. Measurements of Standard Model processes are essential for comparison with theoretical calculations and modeling. This talk will present the latest results from ATLAS using data collected in 2011 and 2012 at energies of 7 and 8 TeV. The topics studied include QCD studies, top quark physics, and vector boson production.
Speaker: Matthew Scott Rudolph (University of Toronto (CA))
Global Sequantial Calibration of jets at ATLAS 15m
In the ATLAS experiment the measurement of hadronic final states usually involves the detection of collimated cones of particles, more simply called *jets*. Despite all the efforts at the hardware and software levels to correctly reconstruct the 4-momenta of jets, there is still room for improvement. Many factors can influence the shapes and amounts of energy deposited in detectors; for example, gluon-initiated and quark-initiated jets have different radiation patterns. A sequential jet calibration based on global properties of jets (Global Sequential Calibration, or GSC) measured by the ATLAS detector was developed to account for these differences. This calibration, based on Monte Carlo studies, aims to reduce the flavour uncertainty and to improve the resolution of jets. In the case of high-energy jets, a correction is introduced to account for the energy lost by jets that are not contained within the calorimeters (leakage). An overview of this calibration and the performance expected is presented. The GSC was derived for $\sqrt{s}=8\mathrm{TeV}$ and jet sizes of R=0.4 and R=0.6.
Speaker: Santiago Batista (University of Toronto (CA))
Measurement of the top quark polarization in semi-leptonically decaying top-antitop pairs with the ATLAS detector 15m
The Standard Model predicts that top-antitop pairs produced through the strong interaction will have zero net longitudinal polarization due to parity conservation. Physics beyond the Standard Model could allow for non-parity conserving top-antitop pair production which would produce a net polarization signal at the Large Hadron Collider. I will present a measurement of the average polarization of top-antitop pairs decaying to the lepton plus jets final state as measured by the ATLAS detector at a centre of mass energy of sqrt(s) = 8 TeV. Events passing selection criteria expected of top-antitop pairs decaying to two b-quarks jets, two light quark jets, a lepton (electron or muon) and a neutrino, are included in the measurement. The measured jets, lepton and missing transverse energy are used as inputs to a kinematic fit which solves for the 4-momentum of the neutrino, which is not detected. The polarization can then be extracted from the distribution of angles formed between the lepton and leptonically decaying top quark in that quark's rest frame.
Speaker: Garrin Mcgoldrick (University of Toronto (CA))
Higgs Particle Searches with ATLAS 30m
This contribution will present the latest results on the Higgs searches performed with the ATLAS detector, including beyond the Standard Model (BSM) Higgs searches, as well as the recently discovered Higgs particle consistent with the Standard Model (SM). Special attention will be given to the decays of the Higgs particle to gauge bosons.
Speaker: Doug Schouten (TRIUMF (CA))
(M1-5) Quantum Gravity and Quantum Cosmology - DTP / Gravité quantique et cosmologie quantique - DPT C-304
Convener: Gabor Kunstatter (University of Winnipeg)
An overview of Loop Quantum Gravity 30m
The definition of a quantum theory for gravity is a long standing problem. Currently, different approaches exist. In this talk, I will present the main ideas behind Loop Quantum Gravity and the Spinfoam frameworks. These are attempts to quantize directly General Relativity using respectively Dirac's canonical quantization and Feynman's path integral quantization. I will give an overview of these dual frameworks, focussing on their successes but also on the difficulties and problems they face.
Speakers: Aristide Baratin (University of Waterloo), Dr Florian Girelli (University of Waterloo)
Possible Astrophysical Observables of Quantum Gravity Effects near Black Holes 30m
Recent implications of results from quantum information theory applied to black holes has led to the confusing conclusions that requires either abandoning the equivalence principle (e.g. the firewall picture), or the no-hair theorem (e.g. the fuzzball picture), or even more unpalatable options. The recent discovery of a pulsar orbiting a black hole opens up new possibilities for tests of theories of gravity. We examine possible observational effects of semiclassical quantum gravity in the vicinity of black holes, as probed by pulsars and event horizon telescope imaging of flares. Pulsar radiation is observable at wavelengths only two orders of magnitude shorter than the Hawking radiation, so precision interferometry of lensed pulsar images may shed light on the quantum gravitational processes and interaction of Hawking radiation with the spacetime near the black hole. This paper discusses the impact on the pulsar radiation interference pattern, which is observable through the modulation index in the foreseeable future, and discusses a possible classical limit of BHC.
Speaker: Prof. Ue-Li Pen (University of Toronto, CITA)
The Everyday Phenomena of Black Hole Chemistry 15m
The cornerstone of thermodynamics is the first law, which for a black hole identifies thermodynamic energy with its mass, temperature with its surface gravity, and entropy with its area. Recent work that posits the identification of a cosmological constant with thermodynamic pressure results in black holes behaving somewhat like chemical systems, with pressure-volume terms appearing in the first law and the black hole mass interpreted as enthalpy instead of energy. This perspective on black holes leads to a broad range of novel and interesting phenomena that have counterparts in everyday chemical thermodynamics, including liquid–gas Van der Waals transitions, reentrant phase transitions seen in the mixing of two liquids, and the analogue of a triple point.
Speaker: Robert Mann (U)
Quantum Gravity and Accelerated Frames 15m
We formulate quantum field theory in accelerated frames using Prigogine transformations. We then derive a background independent formulation of such transforms, and attempt a new formulation of quantum gravity.
Speaker: Arundhati Dasgupta (University of Lethbridge)
(M1-6) Testing Fundamental Symmetries I - DNP-PPD-DTP-DIMP / Tests de symétries fondamentales session 1 - DPN-PPD-DPT-DPIM C-309
Convener: Gerald Gwinner (University of Manitoba)
Testing Fundamental Symmetries with the Next Generation Ultracold Neutron Source at TRIUMF 30m
Ultracold neutrons are neutrons that have been cooled below 3 mK. At this temperature they travel at a speed less than ~8 m/s and exhibit the peculiar behavior of being able to be stored in magnetic, material, and gravitational bottles for periods ranging up to their beta-decay lifetime (~15 min). They present a new avenue for performing fundamental neutron experiments such as: searching for a non-zero neutron electric dipole moment (nEDM), precise measurement of the neutron lifetime, and precise measurements of neutron beta decay correlation coefficients to name a few. These measurements have important consequences for extensions to the standard model of particle physics which could help explain the baryon asymmetry of our universe. In the past, UCN were obtained by cooling neutrons from fission based nuclear reactors. However over the last 15 years several new sources of UCN, called super thermal sources, have been pioneered. Here spallation neutrons are cooled by cryogenic convertors and afford UCN densities many orders of magnitude over reactor based systems. One such super thermal source based on conversion in superfluid helium is being developed at RCNP (Japan) and will be moved and installed at TRIUMF (Canada) in 2016. The first experiment planned is a highly anticipated measurement of the neutron's EDM with an order of magnitude better sensitivity than current measurements. I will provide an overview of the rich physics opportunities available to UCN experiments and the current status of the TRIUMF UCN source.
Speaker: Dr Russell Mammei (The University of Winnipeg)
First Determination of the Proton's Weak Charge 30m
The Qweak collaboration has reported first results of a program of precision measurements of parity violating electron-proton scattering at small momentum transfer at Jefferson Laboratory[1]. Together with earlier measurements at higher momentum transfer, which are used to constrain hadronic corrections, this initial Qweak data set has provided the first experimental determination of the proton's weak charge. Results are in good agreement with the Standard Model and set new limits on the neutral weak quark couplings C1u and C1d. Approximately 25x more data are currently undergoing analysis, with the aim of providing a stringent experimental test of the running of sin2(θW) when completed. As part of its ancillary measurement program to constrain and characterize systematic errors, Qweak has also obtained precision measurements of transverse polarization asymmetries, inelastic asymmetries, and parity violating scattering on aluminum. An overview of the Qweak experiment and the status of Qweak physics results will be presented. [1.] D. Androic et al., Physical Review Letters 111, 141803 (2013)
Speaker: Dr Shelley Page (University of Manitoba)
Using the Xe-129 co-magnetometer as a tool to improve the neutron electric dipole moment limit 15m
For more than half a century now, the neutron Electric Dipole Moment (nEDM) experiments have ruled out more CP-violation theories than any other violating type of experiments in history of physics. All the new generation nEDM experiments use a modified NMR technique and are aiming to reduce the current upper limit by one to two orders of magnitude by means -among others- of improving the statistical and systematic errors. The Xe-129 optical co-magnetometer is expected to be a very useful tool to characterise accurately the magnetic field experienced by ultra-cold neutrons (UCN) while storage. The higher the Xe gas pressure the stronger the emitted optical signal which is used to measure the precession frequency of the polarised gas atoms. On the other hand, the presence of Xe-129 gas results in a lower neutron storage lifetime due to the finite capture cross section and leads to electrical breakdown and subsequently to a decreased high-voltage across the UCN storage cell. Both of these factors limit the sensitivity of the experiment. In lack of experimental data, I am working on testing the high voltage (around 15 kV/cm) stability using Xe-129 alone and in mixture with other gases in the few mTorr region seeking to find the optimum conditions of gas pressure/composition and electrodes separation. The results of these tests are expected to be implemented on the nEDM experiment at KEK-RCNP/TRIUMF.
Speaker: Dr Katerina Katsika (TRIUMF)
(M1-7) Ultrafast Imaging and Spectroscopy I - DAMOPC / Imagerie ultrarapide et spectroscopie I - DPAMPC C-207
Convener: Jim Martin (University of Waterloo)
Ultrafast Optical Control of Quantum Dot Excitons Using Engineered Optical Pulses 30m
Femtosecond pulse shaping provides a flexible approach to tailoring the Hamiltonian governing the interaction of light with matter. Together with powerful adaptive feedback algorithms, this approach is now used routinely in the control of a variety of physical processes. For quantum computing applications, pulse shaping provides a means to optimize the speed and fidelity of elementary quantum gates, and may enable the realization of schemes for complex instruction set quantum computing. In this presentation, I will discuss our recent experiments demonstrating ultrafast quantum control of charge based (exciton) qubits in semiconductor quantum dots. Using optimal quantum control techniques, we show that pulse shaping provides a means to optimize the fidelity of a C-ROT gate in single quantum dots [1,2], and enables parallel single qubit gates on distant quantum dots within the laser focal spot [3]. We also demonstrate adiabatic rapid passage on a subpicosecond time scale in single semiconductor quantum dots, yielding new insight into the role of phonons in dephasing of exciton qubits. 1. A. Gamouras, R. Mathew, and K. C. Hall, J. Appl. Phys. 112, 014313 (2012). 2. R. Mathew, C. E. Pryor, M. E. Flatte, and K. C. Hall, Phys. Rev. B 84, 205322 (2011). 3. A. Gamouras, R. Mathew, S. Freisem, D. G. Deppe, and K. C. Hall, Nano Letters 13, 4666 (2013).
Speaker: Prof. Kimberley Hall (Dalhousie University)
Ultrafast dynamics of a polariton gas in organic-semiconductor Fabry-Perot microcavities 30m
In high-$Q$ microcavities, non-perturbative mixing of the highly confined electromagnetic field and exciton resonances results in new quasi-particles termed exciton-polaritons. These are composite bosons with very low effective mass ($< 10^{-4} m_e$). Above a certain critical density and below a critical temperature, these can undergo Bose-Einstein Condensation (BEC), resulting in macroscopic spontaneous coherence. BEC has been well-documented in inorganic quantum-well microcavities, while this effect has not been convincingly demonstrated for molecular materials. Nevertheless, larger oscillator strengths and higher exciton binding energies should permit polariton condensates at higher temperature than in inorganic devices, even at room temperature, if the coupling is larger than the disorder width. In this oral contribution, I will describe recent efforts to unravel polariton-polariton nonlinear coupling by means of two-dimensional electronic coherence spectroscopy (2D-ECS). It is an ultrafast spectroscopic technique belonging to the family of 2D Fourier Spectroscopies and it allows to measure correlations between quantum transitions induced by the electromagnetic field. In 2D-ECS a sequence of four phase-related ultrafast optical pulses excites quantum states of a material system. Each pulse separately excites a quantum wave packet with spectral phase and amplitude imparted by that pulse, while the effect of the pulse sequence is to collectively excite multiple quantum coherences. Interferences between the various combinations of the pulses wave-packets determine linear and non-linear contributions to the material optical response. With this technique, we address polariton-polariton coupling dynamics towards the formation of quantum condensates.
Speaker: Prof. Carlos Silva (Université de Montréal)
Dissociative Excitation of Thymine by Electron Impact 15m
A crossed electron-gas beam system coupled to a VUV spectrometer has been used to investigate the dissociation of thymine (C5H6N2O2) into excited atomic fragments in the electron-impact energy range from threshold to 375 eV. A special stainless steel oven is used to vaporize the thymine and form it into a beam where it is intersected by a magnetically collimated electron beam, typical current 50 µA. The main features in the spectrum are the H Lyman series lines. The probability of extracting excited C or N atoms from the ring is shown to be very small. In addition to spectral data, excitation probability curves as a function of electron energy will be presented for the main emission features. Possible dissociation channels and excitation mechanisms in the parent molecule will be discussed. The authors thank NSERC (Canada) for financial support.
Speaker: Collin Tiessen (U)
Health Break / Pause santé Alumni Hall + Foyer
Alumni Hall + Foyer
(M2-1) ePOP Satellite Mission II - DASP / Mission satellitaire ePOP II - DPAE C-205
Convener: Jean-Marc Noel (Royal Military College)
Modelling Van Allen Probes Observations of ULF waves and Outer Radiation Belt Electron Dynamics 30m
Pc5 waves with toroidal and poloidal electric fields are ubiquitous in Earth's magnetosphere and are often present in the recovery phase of geomagnetic storms. We present results of simulations of Pc5 wave-particle interactions and show how they can be used to explain Cluster (1) and Van Allen Probes (2) observations of shock-initiated outer radiation belt electron flux enhancements and modulations. Theory suggests Pc5 waves are capable of producing such modulations over energies that range from 10's of keV to greater than 1MeV. Using a model of ULF waves, and constraints from satellite observations, we show that solar wind pressure pulses can excite Pc5-range ULF waves and, through drift-resonance interaction, energize electrons in the outer belt. We examine the electron response to pressure-pulse excited waves by evolving electron phase space density in a kinetic transport model that ingests time series from the wave model. The kinetic simulations reveal various features of the interaction, including prompt adiabatic energization by the pressure pulse, drift echoes of this signature at the location of virtual satellites placed in the model, and enhancements and modulations in phase space density that are in agreement with observations. 1. Zong, Q.-G et al., "Energetic electron response to ULF waves induced by interplanetary shocks in the outer radiation belt", J. Geophys. Res, 114, A10204, doi:10.1029/2009JA014393 (2009). 2. Claudepierre, S.G. et al., "Van Allen Probes observation of localized drift resonance between poloidal mode ultra-low frequency waves and 60 keV electrons", Geophys. Rev. Lett., 40, p.4491-4497, doi:101002/grl.50901 (2013).
Speaker: Robert Rankin (U)
Initial transionospheric HF observations by the Radio Receiver Instrument (RRI) on the enhanced Polar Outflow Probe (ePOP) satellite mission 30m
The Cascade Small-Sat and Ionospheric Polar Explorer (CASSIOPE) satellite was successfully launched and began operations in late September of 2013. The suite of 8 scientific instruments on CASSIOPE comprise the enhanced Polar Outflow Probe (ePOP). One instrument is the Radio Receiver Instrument (RRI) which is used to measure radio waves, from 10 Hz to 18 MHz, on two crossed 6-m dipole antennas. The first reception by the RRI of a dedicated ground transmission, at 14.01 MHz, was from the Saskatoon SuperDARN coherent scatter radar on 7 November, 2013. A similar pass on 17 January, 2014 was also successful and such experiments are continuing. The unique eight-pulse sequence transmitted by the Saskatoon SuperDARN radar was clearly observed throughout the passes on both mentioned days. A comparison of signal parameters received by the RRI (e.g., time delay, signal strength, and differential mode delay) and ray tracing simulations of the same parameters shows good agreement. This presentation will present these initial results, as well as additional RRI-SuperDARN experiment configurations and their results as related to radio wave propagation through the ionosphere. It will also included a discussion of the absolute time abilities of the experiment, which are essential for its successful operation.
Speaker: Glenn Hussey (University of Saskatchewan)
e-POP Magnetic Field Instrument (MGF) - Instrumentation and Early Results 30m
The scientific objective of the Enhanced Polar Outflow Probe (e-POP) is to study plasma outflows, neutral atmospheric escape, and associated effects of auroral currents and plasma microstructures on radio propagation at an unprecedented level of detail. Field-aligned currents are an important coupling process between the Earth's magnetosphere and the polar ionosphere. Field-aligned currents may be detected via measurements of magnetic gradients along the track of a polar orbiting spacecraft. The detection of gradients does not require observatory class measurements of the geomagnetic field. The Magnetic Field Instrument (MGF) uses two fluxgate magnetometers to measure the DC and low frequency magnetic field and detect and remove the stray field from the spacecraft. The fluxgate sensors are based on the MAGSAT design and are mounted on a modest 80 cm carbon-fiber boom. They are double wound for reduced mass and cross-field dependence. The MGF measures the magnetic field at 160 samples per second to a resolution of 0.0625 nT. Data output is 1952 bytes per second including temperature measurements. Power consumption is 2.2 watts. Noise levels of 7 pT per root Hz at 1 Hz were obtained using sensors built with Infinetics cores. The MGF has been successfully commissioned and is available for science observations. This presentation will review the capability of the instrument, describe the routinely generated science data products and present some early results from the instrument.
Speaker: Mr David Miles (University of Alberta)
(M2-10) Testing Fundamental Symmetries II - PPD-DTP-DNP / Tests de symétries fondamentales II - PPD/DPT/DPN C-309
Convener: Zisis Papandreou (University of Regina)
Superallowed Fermi Beta Decay Studies at TRIUMF-ISAC 30m
High-precision measurements of the ft-values for superallowed Fermi beta decays between nuclear isobaric analogue states provide a number of demanding tests of the electroweak Standard Model, including confirmation of the Conserved Vector Current (CVC) hypothesis at the level of 1.3 parts in 10,000, the most stringent limits on weak scalar current contributions, and the most precise determination of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix element V_ud. In addition to high-precision experimental measurements, these tests rely on small (order 1%) theoretical corrections for radiative effects and the breaking of isospin symmetry by Coulomb and charge dependent forces in the nucleus. The latter, in particular, depend strongly on nuclear structure, motivating further studies by a wide variety of theoretical approaches, as well as continued high-precision experimental tests. At the Isotope Separator and Accelerator (ISAC) facility at TRIUMF, 500 MeV proton beams of up to 100 microamps have been used to generate high-quality ISOL beams of several of the superallowed emitters with world record intensities. Superallowed half-lives have been measured with record precision using a 4pi gas proportional beta counter and tape transport system, the 8pi gamma-ray spectrometer at ISAC has been used to perform both superallowed branching ratio measurement and high-precision half-life measurements via gamma-ray counting, and the TITAN Penning trap mass spectrometer has demonstrated the first high charge-state mass measurement for a short-lived superallowed emitter. In this presentation, recent highlights from the superallowed program at ISAC, including high-precision measurements for 10C, 14O, 18Ne, 26Al, and 74Rb superallowed decay, will be presented. The impact of these measurements on tests of isospin symmetry breaking in superallowed decays will be discussed and future developments in the superallowed program at ISAC, including the installation of the new GRIFFIN gamma-ray spectrometer, will be presented.
Speaker: Prof. Carl Svensson (University of Guelph)
CAP2014_Svensson_Indico.pdf
CAP2014_Svensson_Indico.pptx
High-Precision Half-Life and Branching Ratio Measurements For The Superallowed $\beta^{+}$ Emitter $^{26}$Al$^m$ 30m
High-precision half-life and branching-ratio measurements for the superallowed $\beta^+$ emitter $^{26}\mathrm{Al}^m$ were performed at the TRIUMF-ISAC radioactive ion beam facility located in Vancouver, Canada. The branching ratio measurement was performed with the 8$\pi$ Spectrometer, an array of 20 high-purity germanium detectors, in conjunction with SCEPTAR, a plastic scintillator array used to detect the emitted beta particles. An upper limit of $\le$ 12 ppm at 90$\%$ confidence level was found for the second forbidden $\beta^+$ decay of $^{26}\mathrm{Al}^m$ to the state at 1809 keV in $^{26}\mathrm{Mg}$. An inclusive upper limit of $\le$ 15 ppm at 90$\%$ confidence level was found when considering all possible non-analogue $\beta^+$/EC decay branches of $^{26}\mathrm{Al}^m$, resulting in a superallowed branching ratio of $100.0000^{+0}_{-0.0015}\%$. The half-life measurement was performed using a 4$\pi$ continuous-flow gas proportional counter and fast tape transport system. The resulting value for the $^{26}\mathrm{Al}^m$ half-life, T$_{1/2} = 6.34654(76)$ s, is consistent with, but 2.5 times more precise than, the previous world average, and represents the single most precisely measured half-life of any superallowed emitting nucleus to date. Combining these results with world-average $Q$-value measurements yields a superallowed $\beta$-decay ${ft}$ value of 3037.58(60) s, the most precisely determined ${ft}$ value for any superallowed emitting nucleus to date. Combined with the small, and precisely quoted, theoretical isospin-symmetry-breaking corrections for this nucleus, the corrected ${\mathcal{F}t}$ value for $^{26}\mathrm{Al}^m$ of 3073.1(12) s is also the most precisely determined for any superallowed emitter by nearly a factor of two and now rivals the precision of all the other 12 precisely measured superallowed $\beta$ decays combined. The high-precision experimental ${ft}$ value for $^{26}\mathrm{Al}^m$ superallowed decay reported here provides a new benchmark to refine theoretical models of isospin-symmetry-breaking effects in superallowed Fermi $\beta$ decays.
Speaker: Paul Finlay (Katholieke Universiteit Leuven (BE))
HIGH-PRECISION HALF-LIFE MEASUREMENTS FOR THE SUPERALLOWED β+ EMITTER 10C 15m
High precision measurements of superallowed Fermi beta transitions between 0$^+$ isobaric analogue states allow for stringent tests of the electroweak interaction described by the Standard Model. Particularly, these transitions provide an experimental probe of the unitary of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, the Conserved-Vector-Current (CVC) hypothesis, as well as set limits on the existence of scalar currents in the weak interaction. Half-life measurements for the lightest of the superallowed emitters are of particular interest as it is the low-Z superallowed decays that are most sensitive to a possible scalar current contribution. There are two methods for measuring the superallowed $\beta$ decay half-life of $^{10}$C: via directly counting the $\beta$ particles or measuring the $\gamma$-ray activity following $\beta$ decay. Previous results for the $^{10}$C half-life measured via these two methods differ at the 1.5$\sigma$ level, prompting simultaneous and independent measurements of the $^{10}$C half-life using both techniques. Since $^{10}$C is the lightest nucleus for which superallowed $\beta$ decay is possible, a high precision measurement of its half-life is essential for obtaining an upper limit on the presence of scalar currents in the weak interaction. In October 2013, $^{10}$C half-life measurements via both gamma-ray photo-peak and direct beta counting were performed at TRIUMF's Isotope Separator and Accelerator (ISAC) facility using the 8$\pi$ spectrometer and a $4\pi$ gas proportional $\beta$ counter at the ISAC General Purpose Station. The 8$\pi$ $\gamma$-ray spectrometer consists of 20 High Purity Germanium (HPGe) detectors as well as the Zero Degree $\beta$ detector, a fast plastic scintillator located at the end of the beam line within the 8$\pi$. This presentation will highlight the importance of these measurements and preliminary half-life results for $^{10}$C will be presented.
Speaker: Michelle Dunlop (U)
Atomic Magnetometry for Neutron EDM experiment at TRIUMF 15m
The neutron electric dipole moment (EDM) experiment at TRIUMF aims to constrain the neutron EDM to the 1 x 10^{-27} level in its initial phase of operation. At this level of precision, magnetic stability must be measured at the tens of fT level in the 1 uT operating field of the experiment. Comagnetometers based on Hg-199 and Xe-129 will be used to measure this stability in real time inside the neutron EDM cell, at the same time as the EDM measurement is being conducted. Furthermore, external magnetometers with similar precision would be used to confirm the magnetic environment with a similar level of precision around the neutron EDM measurement cell. We have been developing external magnetometers based on non-linear magneto-optical rotation (NMOR) in rubidium vapour, based on the successful techniques developed by Budker, et al. Magnetometers based on this principle promise to provide the precision necessary for the EDM experiment. Recent results from our prototype NMOR system at the University of Winnipeg will be presented.
Speaker: Prof. Jeffery Martin (The University of Winnipeg)
(M2-2) Nuclear Astrophysics - DNP / Astrophysique nucléaire - DPN C-301
Convener: Barry Davids (TRIUMF)
Nuclear astrophysics with DRAGON 30m
The DRAGON facility at TRIUMF measures radiative proton and alpha capture reactions relevant to nucleosynthesis in a variety of astrophysical scenarios. DRAGON experiments are performed in inverse kinematics, taking advantage of the intense radioactive and stable beams available at TRIUMF. In this talk, I will present an overview of recent activities at DRAGON, which include the first successful measurement with a high mass beam, 76Se; measurement of proton capture on radioactive 38K; and extensive upgrades to the data acquisition system and installation of low-intensity beam diagnostics. I will also discuss some future plans for DRAGON, including an indirect measurement of the 330 keV resonance in 18F(p,g) via 15O(a,g) and 15(a,a).
Speaker: Dr Gregory Christian (TRIUMF)
Measurement of the p-process branching point reaction 76Se(α,γ)80Kr at DRAGON 15m
The photo-disintegration process (*p*-process) is thought to be the primary method by which the rare *p*-nuclides (stable isotopes that cannot be produced by either the slow (*s*) or rapid (*r*) neutron capture processes) are produced. This process occurs in the high temperature environments in the late stages of massive stars and in their subsequent explosion as core collapse supernovae. Recent work to explore and expand the capabilities of the DRAGON recoil separator to beams of mass A > 40 has enabled us to make our first measurement of an important *p*-process reaction: 76Se(α,γ)80Kr. This reaction is of particular interest as 80Kr is a possible branching point of the *p*-process. The relative reaction rates of the 80Kr(γ,α)76Se, 80Kr(γ,n)79Kr, and 80Kr(γ,p)79Br will determine the reaction flow from this point, which in turn affects the resulting abundance of p-nuclide 78Kr. This measurement and its implications, as well as the preliminary high mass tests. will be discussed.
Speaker: Dr Jennifer Fallis (TRIUMF)
Current Status of the Canadian Penning Trap Mass Spectrometer at the CARIBU Facility 15m
The astrophysical r-process is thought to be responsible for the formation of almost half the elements in the universe heavier than iron. The r-process reaction path is located on the neutron-rich side of the chart of the nuclides approaching the neutron drip line. Reaction rates of the r-process and the location of the path are dependent on the neutron separation energies of the nuclei. As the neutron separation energies are derived from the mass of the nuclei, high precision mass measurements are vital. Currently, most of the nuclei in possible r¬-process paths are beyond experimental reach due to their short lifetimes and difficulties in production so their masses must be predicted by theoretical models. Mass measurements allow testing and refinement of these models and provide new data of astrophysical interest. Our group uses the Canadian Penning Trap Mass Spectrometer at the Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory to measure masses of nuclei with lifetimes approaching on the order of 100ms and precisions down to 10 ppb. Changes made to the instrument system have improved the transmission efficiency of ions to the trap, allowing the investigation of shorter lived species. At present, the masses of over 70 species have been measured. The planned implementation of a new ion detector will allow phase imaging cyclotron frequency measurements, further increasing the number of exotic nuclei accessible. We present, in this talk, recent and future upgrades that will allow measurements of shorter lived, more exotic, isotopes that are of interest for studies of the r-process path.
Speaker: Graeme Morgan (U)
Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei 15m
Several groups from universities across Canada are collaborating on the GRIFFIN (Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei) project to significantly upgrade the decay spectroscopy capabilities at TRIUMF-ISAC. GRIFFIN will replace the HPGe aspect of the 8pi spectrometer with an array of 16 large-volume hyper-pure germanium clover detectors instrumented with a state-of-the-art digital data acquisition system. This Canadian-led project will serve both the national and international interests in low-energy nuclear physics research at TRIUMF-ISAC. The facility will make use of all the ancillary detector systems developed for the 8pi spectrometer which include the SCEPTAR array for beta-tagging, PACES for high-resolution internal conversion electron spectroscopy and an array of lanthanum bromide scintillators for fast gamma-ray timing measurements. In addition, GRIFFIN will accommodate arrays of neutron detectors, such as the DESCANT array developed by the University of Guelph and TRIUMF, to enable studies of beta-delayed neutron emitting nuclei relevant for the astrophysical r-process. The low-energy area of ISAC-I is being reconfigured and the new experimental equipment is being installed during the first half of 2014. It is planned to performed experiments using an early-implementation of the GRIFFIN facility during the Fall schedule of 2014. The array will be fully completed in 2015 with the full complement of 16 clovers. GRIFFIN will greatly enhance the capabilities in the nuclear structure, nuclear astrophysics and fundamental symmetries research programs with stopped radioactive beams available from ISAC and in the future ARIEL. A detailed overview and progress update of the GRIFFIN project will be presented.
Speaker: Dr Adam Garnsworthy (TRIUMF)
GRIFFIN Detector Acceptance Tests 15m
Gamma-Ray Infrastructure For Fundamental Investigation of Nuclei (GRIFFIN) is a state-of-the-art facility for spectroscopic studies following nuclear decay being built at TRIUMF, Vancouver, B.C. It will accommodate 16 detectors, each made of four high purity Germanium crystals arranged in a clover configuration. GRIFFIN's efficiency will allow decay spectroscopy studies to be extended to regions far from stability that are currently not accessible at TRIUMF. Individual GRIFFIN detectors are delivered to SFU for acceptance tests. To accommodate these detectors an automatic LN$_2$ cooling system, as well as analog and digital data acquisition systems have been set up to carry out the acceptance tests. Software analysis tools and experimental procedures have also been established to examine the consistency of the hardware with the list of specifications provided by the GRIFFIN collaboration. The acceptance tests include measurements of energy resolution, absolute efficiency, analog timing resolution with respect to a BaF$_2$ scintillator, preamplifier and cryogenic properties, and mechanical dimensions. As of February 2014, eleven GRIFFIN detectors have been delivered by the manufacturer and nine have been fully accepted and transferred to TRIUMF. Several additional investigations of the GRIFFIN clover performance have been undertaken. The improvement in photopeak efficiency via energy add back of gamma rays which scatter between the four crystals of a clover has been measured with standard calibration sources. Digital timing resolution with respect to a BaF$_2$ scintillator has been measured using 14-bit, 100 MHz digitizer cards. An absolute efficiency response curve has been measured in the 80-3500 keV energy range. In addition, GRIFFIN detectors were incorporated into a charged-particle-gamma-ray coincidence setup enabling studies of the angular distribution of gamma rays following $^{241}$Am alpha decay. In this presentation the details of the aforementioned tests will be discussed.
Speaker: Usman Rizwan (Simon Fraser University)
(M2-3) Advances in PP and NP Theory - DTP-PPD-DNP / Progrès en théorie des particules et des noyaux - DPT-PPD-DPN C-304
Convener: Rainer Dick (University of Saskatchewan)
Microscopic simulations with modern nuclear forces 30m
I will first go over the status of modern nuclear theory, especially in connection with first-principles studies of strongly interacting nucleons. After some general points on the underlying theory of Quantum Chromodynamics (QCD), I will go over the efforts toward connecting QCD with many-nucleon studies (via chiral Effective Field Theory [EFT]). I will then introduce a recent local reformulation of chiral EFT, which makes it possible to use such modern potentials within the framework of Quantum Monte Carlo (an essentially exact type of microscopic simulation method).
Speaker: Alexandros Gezerlis (University of Guelph)
The long arm of the lattice 30m
Lattice simulations have an impact that reaches into several aspects of QCD and nuclear physics as well as the standard model of particle physics and theories beyond. A selection of recent examples will be reviewed.
Speaker: Randy Lewis (York University)
Coupled-channel vibrational-model studies of nucleon scattering from oxygen isotopes and the corresponding mirror systems. 15m
A Multi-Channel Algebraic-Scattering (MCAS) method that was developed in 2003 for the analysis of low-energy nuclear spectra and of resonant scattering has continued to be effectively used for nuclear-structure studies. The focus now is on nuclei away from the valley of stability. Such nuclei are the subject of experimental study at Radioactive Ion Beam (RIB) facilities, and may have application to astrophysics. The MCAS approach allows the construction of the nucleon-core model Hamiltonian which can be defined in detail (coupling to the collective modes, diverse components of the interaction operators, nonlocal effects due to Pauli exclusion). As reported at previous CAP congresses, MCAS analyses have given good descriptions of bound states and low-lying resonant spectra of medium-light nuclei. This presentation deals with new results for oxygen isotopes, and their mirror systems, using a vibrational model to construct the nucleon-nucleus potential matrices used in MCAS. New results will be shown for n+16O and p+16O, as well as preliminary results for nucleon plus 18O.
Speaker: Dr Juris Svenne (University of Manitoba)
Open Charm Production in p + p and Pb + Pb collisions at the LHC 15m
The phase transition from hadronic to partonic degrees of freedom in ultra-relativistic nuclear collisions is a central focus of experiments at the LHC. Heavy-flavor quarks are an ideal probe to study early dynamics in ultra-relativistic nuclear collisions. This contribution will present new results on the effects of strong longitudinal colour electric fields (SCF), shadowing, and quenching on the open prompt charm mesons production in central Pb + Pb collisions at √sNN= 2.76 TeV. This study is done within the framework of the HIJING/BBbar v2.0 model. We show that the above nuclear effects constitute important dynamical mechanisms in the description of experimental data. The strength of colour fields (as characterized by the string tension κ), partonic energy loss and jet quenching process lead to a suppression factor for the open charm production is heavy-ion collisions consistent with recent published data. Predictions for beauty mesons will also be presented. * Work supported by NSERC (Canada), the U.S. Department of Energy and by the Romanian Authority for Scientific Research
Speaker: Prof. Jean Barrette (McGill University)
(M2-4) Neutrinos Long Baseline PPD-DNP / Neutrinos sur de longues distances - PPD-DPN C-112
Convener: Zoltan Gecse (University of British Columbia (CA))
A long distance for the smallest particle: recent results from long baseline neutrino experiments 30m
One of the most promising investigations of beyond-the-Standard-Model physics has been the study of neutrino oscillation, that is, the conversion of neutrinos from one flavor to another as they propagate. While neutrino oscillation is studied in a wide variety of laboratories, the strongest constraints on the neutrino oscillation mixing parameters, theta23 and Dm2(32) come from long baseline neutrino experiments. A long baseline neutrino experiment employs a particle accelerator to produce a neutrino beam which travels 100-1000km in one of the grandest tests of quantum mechanics imaginable. This talk will describe how long baseline experiments are shaping our understanding of neutrino oscillation physics, with the latest results from experiments around the world such as T2K, NOvA, and OPERA.
Speaker: Kendall Mahn (TRIUMF)
Neutrino Cross Sections at the T2K Near Detectors 15m
Measurements of the neutrino oscillation parameters have improved markedly in the last three years, with recent results from T2K casting the first light on possible CP violation in the lepton sector. For these oscillation measurements, systematic errors are becoming as important as the statistical error, and neutrino cross section uncertainties are a major contributor to the total systematic error. To improve our knowledge of neutrino oscillation physics we must therefore improve our understanding of neutrino cross sections. The T2K near detectors provide a good environment to measure neutrino cross sections, with a well understood, high intensity neutrino beam and multiple target elements. The off-axis near detector is also equipped with a magnetic field, which allows the identification of charged particles and precise measurements of their momentum, and a fine grained target to measure vertex activity. This talk will present the published T2K cross section results and describe the work that is currently being done towards future measurements.
Speaker: Dr Mark Scott (TRIUMF)
Identifying Charged Current Single Pion Production Neutrino Events at Super Kamiokande 15m
Super Kamiokande is a large water Cherenkov detector that is used to detect neutrino interactions and measure neutrino oscillation parameters. In Super Kamiokande charged particles are identified by classifying the rings of Cherenkov light, traditionally as either electron-like with a fuzzy ring edge, or as muon-like with a sharp ring edge. A maximum likelihood reconstruction algorithm now makes it possible to identify other particles such as pions. Although the Cherenkov rings produced by muons and charged pions are very similar, charged pions, unlike muons, undergo hadronic interactions in the water which affect the amount and properties of the Cherenkov light they produce. These hadronic interactions make it possible to distinguish charged pions from muons, and by extension to identify charged current single $\pi^{+}$ production neutrino interactions ($\nu_{\mu}+p/n\rightarrow\mu^{-}+\pi^{+}+p/n$) at Super Kamiokande. Charged current single $\pi^{+}$ production neutrino events have never been explicitly identified at Super Kamiokande before, and including them in analyses will require evaluation of the systematic errors associated with charged pion hadronic interactions and Cherenkov light production in water.
Speaker: Sophie Berkman (University of British Columbia)
The NuMu and anti-NuMu interaction rate measurements in the T2K near detector 15m
The neutrino oscillation measurement made by the Tokai-To-Kamioka (T2K) experiment relies greatly on the measurements of the neutrino flux and cross sections from its near detector, ND280. This measurement will be even more crucial when T2K operates with an anti-neutrino beam to investigate CP violation in the neutrino sector. In this mode, the muon neutrino component of the beam will be a significant background for the oscillation measurement, whilst the muon anti-neutrino cross section is not very well known at the T2K neutrino energy peak. This talk will present improvements to the ND280 analyses for the neutrino and anti-neutrino beams.
Speaker: Dr Anthony Hillairet (University of Victoria)
Using the T2K near detector in neutrino oscillation measurements 15m
The neutrino oscillation measurements performed by the Tokai-To-Kamioka (T2K) experiment are dependent on the energy spectrum of the neutrino beam, as well as neutrino cross section model parameters. Measurements made at the near detector (ND280) provide important constraints on these quantities. This talk will discuss how these constraints are derived from ND280 measurements, and show the dramatic impact of ND280 on the T2K neutrino oscillation measurements.
Speaker: Jordan Myslik (University of Victoria)
(M2-5) Magnetic / Frustrated Systems - DCMMP / Systèmes magnétiques / frustrés - DPMCM A-226
Convener: Tami Pereg-Barnea (McGill University)
New Routes to Quantum Spin Liquid Physics 30m
The quantum spin liquid (QSL) is a quantum entangled and dynamical ground state of a magnetic material with strange fractional excitations. This enticing phenomenon was predicted decades ago to occur in materials with competing (frustrated) interactions. However, the road to discovering real materials of this nature is a long one and it is only recently that we have access to several good QSL candidates. Most often the search for QSLs has concentrated on simple frustrated, spin-1/2 models. I will show that some of the most recent discoveries in this vein have come in unusual places, in systems with additional degrees of freedom or larger magnetic moments even on normally unfrustrated lattices. In addition to a general introduction, I will present some of my recent contributions to these discoveries, specifically in measuring magnetic properties at the microscopic (local) level with the nuclear magnetic resonance (NMR) and muon spin rotation (muSR) techniques.
Speaker: Prof. Jeffrey Quilliam (Université de Sherbrooke)
Magnetic Excitations in Thin Film Iridates Probed by Resonant Inelastic X-ray Scattering 15m
We have performed resonant inelastic x-ray scattering (RIXS) measurements on epitaxial thin film samples of the layered perovskite iridates Ba$_2$IrO$_4$ and Sr$_2$IrO$_4$. These compounds display a novel J$_{eff}$ = 1/2 Mott insulating ground state driven by strong 5d spin-orbit coupling effects. By studying 10 to 50 nm thin film samples grown on a variety of different substrates (GSO, STO, LSAT), we have investigated the impact of applied tensile and compressive strain on the characteristic magnetic and electronic excitations of these materials. Unlike other perturbations, such as doping or applied magnetic field, we find that epitaxial strain does not alter the magnetic structure of Ba$_2$IrO$_4$ or Sr$_2$IrO$_4$. However, applied strain does affect the magnetic energy scales of these systems, providing a means of tuning both the ordering temperature (T$_N$) and the strength of the magnetic exchange interactions (J). Most strikingly, we demonstrate that RIXS can be used to perform detailed magnetic dispersion measurements on thin film samples of 10 nm (~4 unit cells) or less.
Speaker: Dr Patrick Clancy (University of Toronto)
Has Compelling Experimental Evidence for Order-by-Disorder at Last Been Found in a Frustrated Magnetic System? 30m
In some magnetic systems, known as frustrated magnets, the lattice geometry or the competition between different spin-spin interactions can lead to a sub-exponentially large number of accidentally degenerate classical ground states, or false vacuua, and thus a sort of landscape problem for condensed matter physicists. Order-by-disorder (OdD) is a concept of central importance in the field of frustrated magnetism. Saddled with large accidental degeneracies, a subset of states, those that support the largest quantum and/or thermal fluctuations, may be selected to form true long-range order. ObD has been discussed extensively on the theoretical front for over 30 years and proposed to be at play in a number of experimental settings. Unfortunately, convincing demonstrations of OBD in real materials have remained scarce. In this talk, I will review the phenomena of thermal and quantum of order-by-disorder and discuss how recent work may have evinced compelling evidence for ObD in some frustrated XY pyrochlore antiferromagnetic materials.
Speaker: Prof. Michel Gingras (University of Waterloo)
(M2-6) Radiation Therapy - DMBP / Thérapie par rayonnement - DPMB C-204
Convener: Eduardo Galiano (Laurentian University)
The unintentional irradiation of a live human fetus: assessing the likelihood of a radiation-induced abortion 30m
Purpose: The purpose of this work was to calculate the dose accidentally absorbed by a live fetus during a diagnostic CT procedure to a pregnant patient, and to assess the likelihood that the premature termination of the pregnancy was radiation-induced. Methods: A patient underwent a diagnostic CT procedure as part of her initial clinical work up for stage II cervical cancer. At the time of imaging - and unbeknownst to the staff – the patient was found to be 12 weeks pregnant. Approximately two weeks later, the fetus became non-viable and was surgically removed. Following established institutional procedures, the case was referred to the Physics Department for further dosimetric evaluation to determine what role - if any - the fetal dose played in the premature termination of the pregnancy. The fetal dose was determined using Wagner's CTDI Phantom Dose Reference Model method. 6 A slice thickness of 6 mm and a CTDIvol of 1.13 mGy were used in our calculations, as suggested in the Abdomen Baby manufacturer's protocol. 7 KVp, mAs, and slice thickness corrections were applied to the CTDIvol, as suggested by Wagner. Results: With these parameters, our estimated absorbed dose to the fetus was 19.3 mGy. Further, we estimate that the rotation of the fetus through an approximate 90º angle along the caudo-cephalic axis during imaging had no clinically relevant effect on the calculated absorbed dose. Conclusions: The fetal dose was well below the consensus levels for negligible risk (50–150 mGy), and the "actionable" level of 150 mGy. 8 At the time of exposure, the fetus was developmentally beyond the critically radiosensitive phase of organogenesis. We conclude that the premature termination of this pregnancy is most unlikely to be of radiological etiology.
Speaker: Prof. Eduardo Galiano (Laurentian University)
Medical Physics Residencies-101: The What's, Where's, and How's 30m
Medical Physics residencies serve as an excellent bridge between putting together the didactic knowledge obtained from a graduate program with practical experience in a Medical Physics sub-specialty. Most residency programs are within the Radiation Therapy sub-specialty, although Diagnostic Imaging-based residencies are slowly starting to become more prevalent over recent years. Residency programs prepare one to take a board examination in order to become a board-certified Medical Physicist. The boards which an individual can apply to are the Canadian College of Physicists in Medicine (CCPM) and the American Board of Radiology (ABR). Residencies can be accredited by the Commission on Accreditation of Medical Physics Educational Programs (CAMPEP) body or are non-accredited. Since CAMPEP states minimum requirements to be met in order to ensure adequate coverage of residency program content, there is a continual push for an increase in the number of CAMPEP-accredited residencies. CAMPEP also accredits Medical Physics graduate programs. Enrolling in an accredited graduate program ensures that the individual graduating obtains a minimum standard of didactic knowledge, which will serve him/her for successful completion of a residency program. This talk will serve to inform the individual of how to prepare for applying to a residency program, what one can expect from a residency program, and where one can apply to residency programs. Participants will also be exposed to how one can prepare for taking a board examination, as well as the general scheme of how the board examinations are administered. CAMPEP requirements for residency and graduate programs will also be discussed.
Speaker: Jeff Frimeth (Xspect Inc.)
Stereotactic Body Radiation Therapy: A New Paradigm for Radiation Therapy 30m
Stereotactic Body Radiation Therapy (SBRT) is a new radiation treatment technique characterized by high dose per fraction (6-30 Gy), a limited number of fractions (1-6) and very accurate and radiation treatments that tightly conform to the disease. SBRT was first reported in Sweden in 1995 and due to favourable clinical evidence has recently spread to a number of disease sites including lung, prostate, liver and oligometastatic sites. A large number of clinical trials are now ongoing investigating the efficacy of SBRT for a number of disease sites. This talk will review the history, radiation biology, treatment technology and clinical evidence supporting SBRT.
Speaker: Mike Oliver (Health Sciences North)
(M2-7) Ultrafast Imaging and Spectroscopy II - DAMOPC / Imagerie ultrarapide et spectroscopie II - DPAMPC C-207
Convener: Paul Barclay (University of Calgary)
Controlling nuclear quantum dynamics with shaped laser pulses 30m
The use of tailored laser pulses to control chemical processes has received much attention over the last 25 years, in part due to the rapid development of experimental pulse shaping techniques. This has permitted studies of control in an ever widening array of systems with increasing complexity (i.e., dimensionality for molecules). In this talk, I will present our computational approach for these problems involving the use of optimal control theory (OCT) for determining laser pulse shapes combined with the multi-configurational time-dependent Hartree (MCTDH) approach for solving the quantum dynamics. MCTDH is a useful approach for solving high-dimensional (4D-21D) problems for molecules. However, for efficiency, MCTDH requires the underlying molecular potential energy and dipole moment surfaces in product form. I will present recent efforts to determine potential energy surfaces for HFCO and HONO based on high-level ab initio results. If time permits, I will discuss initial efforts on the control of dynamics in these systems.
Speaker: Prof. Alex Brown (Department of Chemistry, University of Alberta)
Control of Electron Localization in Molecular Dissociation by a Midinfrared Two-Color Laser Field 15m
Intense femtosecond (10-15s) laser pulses can induce molecular dissociation via a broad range of pathways involving different electronic states. Furthermore, breaking the symmetry of a laser field allows control of these processes via the steering of electron motion, which is accomplished by superimposing electronic states of different parity. The symmetry break can be obtained, for example, by controlling the carrier envelope phase (CEP) of a few-cycle laser pulse, or by combining two laser beams of different wavelength, whose relative phase is adjusted. Both techniques are compared for mid-infrared (MIR) laser pulses (1.8 µm) generated from a laser source that was developed at the Advanced Laser Light Source (ALLS). They lead in many cases to a significant control gain compared to an excitation wavelength of 800 nm. We used a MIR two-color (1.8 µm and 900 nm) laser field to ionize and control H2 and D2 dissociations, thus providing an alternative to CEP stable laser source. By varying the relative phase of both colors, asymmetries (i.e., electron localization selectivity) of up to 15% were calculated directly from a time of flight (TOF) mass analysis. By retrieving fragments position and flight time from their initial spatial location, kinetic energy release (KER) asymmetries up to 30% were also evaluated. Dissociation channels such as the bond softening (BS) channel and the recollision excitation (RCE) channel were identified according to pathways suggested in literature. The results demonstrate a higher level of control compared to previous CEP control experiments and suggest the possibility to shape the proper asymmetric electric field for a specific dissociation channel. The method was further used to ionize and control the deprotonation of C2D2 and C2H2.
Speaker: Mr Vincent Wanie (INRS-EMT/ALLS)
Molecular movies in colour! Coulomb imaging with table top femtosecond laser pulses. 30m
One of the primary objectives of science is to extend our senses to the smallest realms and to observe processes which occur on the fastest time scales. Coulomb explosion imaging using femtosecond, few cycle, laser pulses has been able to make measurements of the structure of small molecules on the angstrom length scale and observe their dynamics on the timescale of a few femtoseconds. Recently, a team from University of Waterloo and INRS working at the Advanced Laser Light Source have employed increasingly ambitious pulse control and wavelength selection, to control and image dynamics with new levels of accuracy. I will give an introduction to the imaging methods used, for non specialists and put our recent results into the context of worldwide efforts. I hope to show that the tabletop femtosecond laser approach has several distinct advantages, over other methods, and that if it continues to develop, by incorporating, the best aspects of complementary approaches, it can continue to set the standard for the near future.
Speaker: Joseph Sanderson (University Waterloo)
Mode invisibility and single-photon detetction
We propose a technique to probe a quantum state of light in an optical cavity without significantly perturbing the photon field. We minimize the interaction of the probe with the field by arranging a setting where the largest contribution to the transition probability is cancelled. We show that we obtain very good resolution for measuring the photon population difference between any given states the photon field by means of atomic interferometry
Speaker: Marvellous Onuma-Kalu (University of Waterloo)
(M2-8) Teaching Physics to a Wider Audience - DPE / Enseigner la physique à un auditoire plus vaste - DEP C-206
Convener: Martin Williams (University of Guelph)
Who should be conducting scientific outreach in high schools? 30m
We all agree that systematic science outreach in high schools is absolutely imperative. But how should we do it? And perhaps as important, who should be doing it? There may be many benefits for increasing the role of postsecondary students in outreach, such as a smaller age gap and better familiarity with the local high school audiences, but lack of literature in the area highlights the need for a national survey on physics outreach in Canada. The talk will outline a project piloted at Acadia University where a physics honour student visited schools with a presentation on physics, his own experiences, and careers in science. It will also be argued that students with research experience, especially students granted the IPP/CERN Summer Student Fellowship or similar awards are in a particularly apt position to participate in physics outreach in high schools.
Speaker: Svetlana Barkanova (Acadia University)
TA Orientation Day for Physics Students at SFU - The Design, the Implementation, and Our Observations 30m
Simon Fraser University, like other universities, has offered an orientation day for teaching assistants for many years. While many of the sessions are aimed at a general audience, physics and other science students usually consider them to be not very useful. To address their needs, we - two faculty members and an educational developer - developed a 6-hour program designed specifically for the needs of our new graduate students who are about to start their first TA job. We will report on the development of this program, how our observations from previous work with first-time TAs influenced our design decisions, and the outcomes that we are aiming for. In particular, we will point out how our program differs from the general audience TA orientation, and how it is integrated with a mandatory course for first year graduate students at SFU called "Introduction to Graduate Studies: Research and Teaching in Physics". We will share the final orientation program, with a focus on some specific examples, and our observations from the first implementation in the Fall of 2013. Some of the feedback we received after the session will also be discussed and compared to reflections by participants after they had completed their first term as TAs.
Speaker: Daria Ahrensmeier (Simon Fraser University)
Round Table: Assessment: what constitutes a "good assessment" 30m
(M2-9) Status and Future of Precision Frontier - PPD-DIMP / État et avenir de la frontière de précision -PPD-DPIM C-114
Convener: Dr Florian Urs Bernlochner (University of Victoria (CA))
Latest results from the B factories 30m
Since the end of data taking in 2008, the BABAR experiment at the SLAC National Accelerator Laboratory, along with its Japanese counterpart, Belle, has continued to produce interesting scientific results spanning a broad range of topics in heavy flavour physics, QCD and searches for physics beyond the standard model. In this talk I will discuss ongoing activities of the BABAR collaboration and present recent highlights from the ongoing physics programs of BABAR and Belle.
Belle-II: searching for new physics in the heavy flavor sector 30m
Belle-II will probe the flavour sector of particle physics at the high-luminosity SuperKEKB e+e- collider, located at the KEK laboratory in Japan. Physics operations will start in late 2016, with the goal of collecting by 2022 thirty times the combined integrated luminosity of the two previous generation B-factories, PEP-II at SLAC and KEKB at KEK. This precision-frontier facility will open an exciting window on new energy scales beyond the reach of existing colliders, including the LHC, by virtue of quantum loop corrections that are sensitive to massive, and as yet undiscovered, particles. These hypothesized particles manifest themselves in precision measurements of processes involving bottom and charm quarks and tau leptons, such as CP violation and other asymmetries, rare decays, and processes that are forbidden within our current understanding of physics. This program is complementary to direct searches for new physics at the LHC. The Canadian group is working on an upgrade of the electromagnetic calorimeter that will enable it to achieve excellent efficiency and resolution in the presence of very high luminosity-related backgrounds. It will use pure CsI crystals with fine mesh photomultiplier tubes and custom analog and digital electronics, which are being designed by the Canadian group. We are aiming for installation in summer 2018.
Speaker: Prof. Christopher Hearty (University of British Columbia/IPP)
Search for the rare $B^-$ $\rightarrow\Lambda\bar{p}\nu\bar{\nu}$ decay at the BaBar experiment 15m
The decay $B^-$ $\rightarrow\Lambda\bar{p}\nu\bar{\nu}$ is a semileptonic, flavour-changing-neutral-current decay. It proceeds exclusively through one-loop box and penguin diagrams and is therefore expected to be heavily suppressed ("rare") within the context of the Standard Model (SM) with a predicted branching fraction of $(7.9 \pm 1.9) \times 10^{-7}$. The possibility of new physics particles contributing in the quantum loops make this decay a very sensitive probe for beyond-SM physics, as any deviation from the predicted decay processes will noticeably affect the suppressed branching fraction. Using data from the BaBar experiment, this analysis aims to establish the first experimentally measured branching fraction limit for this process. In this talk I will describe the experimental and analytical techniques used in this research and present preliminary results.
Speaker: Mr Robert Seddon (McGill University)
Search for the rare B meson decays at the BaBar experiment 15m
Flavour changing neutral current B meson decays, such as $B^{\pm}\to K^{\pm}\tau^{+}\tau^{-}$, are a powerful probe of physics beyond the Standard Model (SM). Comparison of the experimentally measured rate to SM predictions can provide evidence for new physics. Deviations from the SM prediction might arise due to hypothetical heavy particles such as Supersymmetric quarks or bosons or a charged Higgs. Similarly, $B^{\pm}\to K^{\pm}\ell^{+}\ell^{-}$ , where $\ell= e^{+}$ or $\mu^{+}$, has been recently measured by as well as other experiments. The search for $B^{\pm}\to K^{\pm}\tau^+\tau^-$ is specifically interesting, because it involves third-generation leptons, which have greater potential sensitivity to new physics. The search for this rare decay is performed using a sample of 471 million $B{\kern 0.18em\overline{\kern -0.18em B}{}}$, collected with the detector at the PEP-II $e^{+}e^{-}$ collider. The analysis approach is discussed, along with the expected results.
Speaker: Ms Racha Cheaib (McGill University)
Modeling Tau Decays for the Energy and Luminosity Frontiers. 15m
The tau lepton is the heaviest of the known charged leptons and therefore provides a unique tool to probe electroweak interactions, low energy QCD and for searching for new physics. New physics may appear in decays with tau leptons in the final state or in decays of the tau lepton. A key ingredient for any physics programs involving the tau lepton is the modeling of the decay structure. In this paper, recent developments for the modeling of tau decays and the prospects for tau physics at the luminosity and energy frontier will be presented.
Speaker: Ian Michael Nugent (RWTH-Aachen)
Welcome BBQ Reception / Réception d'accueil avec BBQ FA-244+Terrace
FA-244+Terrace
(M-HERZ) Herzberg Memorial Public Lecture - John Ellis, King's College London / Conférence commémorative publique Herzberg - John Ellis, King's College London FA-054+5+6, A-226
FA-054+5+6, A-226
The Higgs Boson and Beyond 1h
Where do we come from? What are we? Where are we going? The discovery of the Higgs Boson at the LHC provides new insights into these basic questions about the Universe, marking the start of a new era in fundamental physics, and opening new vistas in astrophysics and cosmology as well as particle physics.
Speaker: Jonathan R. Ellis (CERN)
Tuesday, June 17
CAP Foundation Annual General Meeting / Assemblée annuelle de la Fondation de l'ACP F-335
8:30 AM → 5:30 PM
Exhibit booths open 08:30-17:30 / Salle d'exposition ouverte de 08h30 à 17h30 Fraser Foyer
Fraser Foyer
(T1-1) Energy Frontier: Higgs Properties - PPD-DTP / Frontière d'énergie : propriétés du boson de Higgs - PPD-DPT C-112
Convener: Doug Schouten (TRIUMF (CA))
Review of the current status of Higgs Properties 30m
I'll report the current status of Higgs property measurements from the Large Hadron Collider experiments ATLAS & CMS. In particular, I'll review the determinations of couplings from combined fits to the individual H -> bosons and H -> fermions channels. Further, the results of hypothesis tests to verify the spin 0 nature of the Higgs and the current knowledge of differential cross section measurements.
Speaker: Dr Florian Urs Bernlochner (University of Victoria (CA))
Higgs: theory review 30m
2012 has been an extremely exciting year for particle physics. The Large Hadron Collider (LHC) at CERN discovered a new particle: the Higgs boson. In this talk I review the properties of this newly discovered particle. In particular, I will present the basics of electroweak symmetry breaking in the Standard Model (SM), that lead to the Higgs discovery. After that, I will discuss how New Physics (NP) beyond the SM can affect the Higgs phenomenology. In particular I will focus on some of the decay channels that could be easily affected by NP: the decay into two b quarks and into two photons.
Speaker: Stefania Gori
**WITHDRAWN** A Search for the Standard Model Higgs Boson Produced via Vector Boson Fusion in the WW Channel using Boosted Decision Trees 15m
In July of 2012, the ATLAS and CMS experiments at the Large Hadron Collider announced the discovery of a new particle that is consistent with the Standard Model Higgs boson produced by gluon fusion. However, in order to avoid problematic divergences at high energies, the Standard Model also requires that the Higgs boson couples to the weak vector bosons. As a result, the search for the Higgs boson produced by vector boson fusion is an important test of the Standard Model. In addition, it also makes it possible to probe the exclusive coupling of the Higgs boson to the weak vector bosons. The ATLAS collaboration has developed a multivariate analysis that searches for the Standard Model Higgs boson that is produced by vector boson fusion and subsequently decays to two leptonically decaying W bosons. This analysis is driven by a boosted decision tree which significantly improves the expected sensitivity over a simple cut-based method.
Speaker: Mr Jacobus Van Nieuwkoop (SFU Simon Fraser University (CA))
Search for the Standard Model Higgs boson produced in association with top quarks in pp collisions at 8 TeV with the ATLAS detector at the LHC 15m
The physics program of the ATLAS experiment pursued at the Large Hadron Collider (LHC) at CERN succeeded in the observation of a new particle in the search for the Standard Model Higgs boson. The Higgs boson production in association with a top-quark pair provides key features to further investigate the nature of the Higgs boson. Its coupling to other bosons was discovered and evidence for its coupling to fermions is given. The associated $t\bar{t}H$ production with the Higgs decay into two bottom quarks provides a good opportunity to probe its coupling strength to top and bottom quarks in the production and decay, respectively. In order to improve the signal sensitivity of the search, multivariate analysis techniques are used to enhance the background and signal separation power relying on robust signal and background models. Therefore, dedicated studies of the $t\bar{t}H$ signal predictions by various Monte Carlo generators at different orders in QCD perturbation theory including differing features and the evaluation of systematic uncertainties assessed to the signal model were studied. The search for the $t\bar{t}H$ ($H \to b\bar{b}$) in pp collisions at ATLAS is presented. The analysis is based on the 8 TeV data recorded during Run I of the LHC and corresponds to an integrated luminosity of 20.3 $\rm fb^{-1}$.
Speaker: Steffen Henkelmann (University of British Columbia (CA))
Search for Standard Model Higgs boson production in association with a top quark pair in the four lepton signature with the ATLAS detector 15m
An overview will be presented of a search for the Standard Model Higgs boson produced in association with a top quark pair decaying into the $t\bar{t}H\to 4\ell$ signature. The study has been performed using data with an integrated luminosity of $\mathcal{L}=20.1 fb^{-1}$ collected by the ATLAS experiment in $pp$ collisions with $\sqrt{s}=8$ TeV at the Large Hadron Collider. This production mode provides direct access to the top quark-Higgs coupling and can be beneficial to this measurement, despite its relatively small cross section. The $4\ell$ analysis, which was carried out in combination with analyses of other multi-lepton final states, is sensitive to three Higgs boson decay modes, $H\to W^+W^-$, $H\to\tau^+\tau^-$ and $H\to ZZ$. The majority of the signal comes from the $W^+W^-$ mode, which is probed by requiring that all W bosons (including those from the top quark decays) decay leptonically. This yields a final state signature which includes two bottom quarks, 4 charged leptons and neutrinos (in the form of missing energy). Preliminary plans for future study of this channel during LHC Run 2 will also be presented.
Speaker: David Anthony Demarco (University of Toronto (CA))
On a Heuristic Point of View Concerning the Mass of the Higgs Boson. 15m
In a recent paper [1] on the modeling of emergent patterns in complex biological and physical systems, an overview of the Bayesian approach [2] that has been used to model the space-time curvature of a static spherically symmetric massive system is presented. Among the emergent properties of such a system, stands a gravitational field that can be described by a modified Newton's law under low speed weak field conditions. Moreover this methodological approach suggests that many physical constants can be seen as emerging numerical patterns, some of which being linked together by specific relationships, once the proper mappings between flat and curved space representations are taken into account. The basic hypothesis behind the present paper is that if all the masses in the Universe have a common origin, through the interaction with a Higgs field, there might be some indirect manifestations of this phenomenon at various scales and may be some relationships could be pointed out between the different masses values as measured in an arbitrary system of units. To highlight this assumption, we briefly explore in the sequel, a few relationships and limits that can be established among reference masses and their measurements (like the electron, the proton and the Higgs boson masses…). This study indirectly suggests that some constants of the Standard Model are not independent, which might reduce their number. [1]Plamondon, R., O'Reilly, C., Ouellet-Plamondon, C., (2014) Strokes against Strokes, Strokes for Strides, Pattern Recognition, 47, 929-944. [2] Plamondon, R."Patterns in Physics: Toward a Unifying Theory",Presses Internationales Polytechnique (2012). [3] Plamondon, R., Ouellet-Plamondon, C., (2014) Emergence of a quasi Newtonian law of gravitation: a geometrical impact study, in Press, Proceedings of the Thirteenth Marcel Grossman Meeting on General Relativity, K. Rosquist, R.T. Jantzen, R. Ruffini, (Eds), World Scientific, Singapore, 1-3.
Speaker: Prof. Réjean Plamondon (École Polytechnique de Montréal)
(T1-2) Testing Fundamental Symmetries III - DNP-DTP-PPD-DIMP / Tests de symétries fondamentales session III - DPN-DPT-PPD-DPIM C-309
Convener: Pierre-Philippe Ouimet (University of Regina)
Testing Fundamental Symmetries with Precision Parity-Violating Experiments: Past, Present and Future 30m
Although the Electroweak Standard Model of Particle Physics has been enormously successful to date, we known it is incomplete. High-precision parity-violating electroweak experiments can provide access to new physics at a wide range of energy scales and play an important complementary role to the LHC research program. The talk will provide an overview on the past, present and future of precision tests of the Standard Model with the special attention on Qweak and MOLLER experiments. The first subset of results from Qweak recently completed at JLab provides the smallest e-p asymmetry ever measured making possible the first determination of the weak charge of the proton. The MOLLER experiment will measure the parity-violating asymmetry in e-e (Møller) scattering proportional to the weak charge of the electron, another excellent place to look for new physics. We will also briefly outline further development of the theoretical and computational approaches to higher-order electroweak effects needed for the accurate interpretation of experimental data. The talk is aimed to physicists in all fields of research.
Progress toward a Measurement of Hadronic Parity Violation in the Capture of Cold Neutrons on Helium-3 15m
The n3He experiment aims to measure the parity violating asymmetry in the direction of proton emission from longitudinally polarized cold neutrons capturing on an unpolarized $^3$He target in the reaction $\vec{n}+^{3}He\rightarrow p+T$. The size of the asymmetry is estimated at $(-9.5)- 2.5\times 10^{-8}$. The goal is to measure this asymmetry with an accuracy of $2\times10^{-8}$ to provide a benchmark for modern effective field theory calculations. The nHe-3 target is also an ion chamber and it will be used to measure the direction of the protons from the break up reaction. It consists of 16 signal wire planes with 144 sense wires, and 17 high voltage planes. Each signal wire will be read out individually to accurately measure the forward-backward shift in the ionization cloud, produced by the protons and tritons, as a function of longitudinal neutron polarization. The cold neutrons are polarized using a supermirror polarizer and guided through the experiment by a 10 Gauss magnetic holding field. The neutron polarization will be reversed using a RF adiabatic spin flipper. In this talk I will present an overview of the experiment, including a detailed description of the target-detector chamber and the measurement concept.
Speaker: Mr Mark Mccrea (University of Manitoba)
The NPDgamma Experiment: Hadronic Parity Violation in the Capture of Cold Neutrons on Protons 15m
The NPDGamma experiment has completed a measurement of the parity-violating directional gamma-ray asymmetry in the capture of cold neutrons on protons in a liquid hydrogen target. The asymmetry is directly related to the weak pion-nucleon coupling constant $h^1_{\pi}$, within the framework of the meson exchange model, and it is related to the effective field theory couplings $\tilde C^{\pi}_6$ and $m_N \rho_t$. The asymmetry has a predicted size of $-5\times 10^{-8} $, with large uncertainties in the theoretical prediction for the coupling constants. The goal precision of the measurement is $1\times 10^{-8}$, which would serve as the most precise constraint on the couplings in both theoretical frameworks. Since the asymmetry is a result of the interference between the weak and strong nucleon-nucleon forces, this measurement also provides an experimental benchmark for theoretical developments in the non-perturbative strong interaction regime. NPDGamma completed a two year long second phase run at the Spallation Neutron Source (SNS), at Oak Ridge National Laboratory and the final analysis is currently ongoing. I will provide an overview of the experiment, the analysis procedure, and some preliminary results.
Observation of Hyperfine Transitions in Trapped Ground-State Antihydrogen 15m
Cold antihydrogen promises a unique opportunity to study the properties of atomic antimatter, and via comparisons with its well-studied matter-counterpart, the possibility to test fundamental symmetries such as CPT invariance. We report the first observation of positron spin flip transitions between hyperfine levels of ground state antihydrogen and the first experimental constraint on the zero-field hyperfine splitting of these atoms. The experiments involved antihydrogen atoms confined in a 0.5 Kelvin deep magnetic potential well, and provides compelling evidence that ground-state are held in the trap for long periods of time. Transitions between hyperfine levels are induced by injecting microwave radiation at appropriate frequencies. The resulting spin flip causes the antihydrogen to be expelled from the trap and the resulting antiproton annihilation is then observed. Remarkably, this experiment was performed with trapping rate of approximately 1 anti-atom/attempt. The observed results will be compared with expectations from simulations of trapped particle dynamics and independent in-situ electron cyclotron resonance measurements of magnetic and microwave field amplitudes. Prospects for experiments that will constrain the zero-field hyperfine splitting of the antihydrogen atom at the $10^{-6}$ level in a newly constructed apparatus will also be discussed. *ALPHA collaboration http://alpha.web.cern.ch; C. Amole, M.D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P.D. Bowe, E. Butler, A. Capra, C.L. Cesar, M. Charlton, A. Deller, P.H. Donnan, S. Eriksson, J. Fajans, T. Friesen, M.C. Fujiwara, D.R. Gill, A. Gutierrez, J.S. Hangst, W.N. Hardy, M.E. Hayden, A.J. Humphries, C.A. Isaac, S. Jonsell, L. Kurchaninov, A. Little, N. Madsen, J.T.K. McKenna, S. Menary, S.C. Napoli, P. Nolan, K. Olchanski, A. Olin, P. Pusa, C. Ø. Rasmussen, F. Robicheaux, E. Sarid, C. R. Shields, D.M. Silveira, S. Stracka, C. So, R.I. Thompson, D.P. van der Werf, J.S. Wurtele.
Speaker: Art on behalf of ALPHA Collaboration Olin (TRIUMF)
Developing a Lithium Doped Glass Detector to Measure the Electric Dipole Moment of Ultra Cold Neutrons 15m
Matter domination over anti-matter in the universe is not explained by the Standard Model. Extensions to the standard model which could account for this lack of anti-matter introduce larger amounts of CP-violation. If neutrons have larger Electric Dipole Moments (EDMs) than predicted by the standard model, this would indicate one source of CP-violation. To measure the neutron EDM to high precision, Ultra Cold Neutrons (UCN) are cooled to temperatures of ~3 mK. UCN have the interesting property that they can be contained in material bottles, and since they move so slowly (~ 7 m/s), they follow ballistic trajectories in gravity. A new high intensity UCN polarized source is being developed at TRIUMF, which is based on a spallation neutron source. UCN from this source will be used to measure the neutron EDM (nEDM) and place stringent limits on models of physics beyond the standard model. In order to detect the high rate of neutrons expected in this new nEDM experiment, a neutron detector capable of high rates ~1.3MHz for a period of several seconds is required. A spin analyzing foil set before the detector means that neutrons of a single spin state are measured at a time. A lithium doped glass scintillator detector, based on the detector used at PSI is being designed. In this talk the principle for how this detector works, and how the high rates of data will be handled will be presented. In addition to handling the high rates, the background rejection, and stability of the efficiency will be considered. One challenge in the nEDM experiment is determining the number of neutrons in the experimental cell, and thus accounting for any variations in UCN production due to moderator temperature changes or number of protons on target. Several possible scenarios for how to normalise the number of neutrons observed to the actual number in the cell are presented, such as using a rate monitor, sequential counting, and simultaneous detection.
Speaker: Ms Lori Rebenitsch (University of Winnipeg/University of Manitoba)
Magnetic Shielding for the Neutron Electric Dipole Moment Experiment at TRIUMF 15m
If a non-zero neutron electric dipole moment (nEDM) were discovered, it would signify a previously unknown source of CP (or T) violation. New sources of CP violation are believed to be required to explain the baryon asymmetry of the universe. The TRIUMF nEDM experiment aims to measure the nEDM to the level $10^{-27}~e\cdot$cm in its initial phase, which is over an order of magnitude more precise than the previous best experiment. The experimental method relies on placing ultracold neutrons in a bottle with electric and magnetic fields and performing precise NMR experiments over hundred second measurement times. The magnetic field B$_0$ in the experimental volume must be strictly controlled during this time, and a combined passive and active magnetic shielding system is being developed to meet the requirements of the experiment. Prototype systems have been constructed at U. Winnipeg. The prototype passive shielding system consists of 4 concentric cylindrical layers of high permeability metal (amumetal), and provides an estimated magnetic field reduction of $10^{6}$, based on Opera simulations. The prototype active shielding system uses a fluxgate magnetometer to provide magnetic field measurements in a Helmholtz-like coil set. The currents in the coils are adjusted by custom software dependent on the fluxgate measurements, forming a feedback loop. The active system provides RMS shielding factors $>$ 1000 for magnetic field perturbation frequencies $\lt$ 20 mHz, and $>$ 100 for frequencies $\lt$0.5 Hz, and can therefore reduce magnetic field variations on the order of tens of $\mu$T to the level of tens of nT. The prototypes represent good progress towards the eventual system for nEDM experiments, where multi-axis low-frequency field drifts of 100 nT require active shielding to <$\sim$1 nT. The present magnetic shielding prototypes will be discussed, with focus on the active shielding system and with view to future improvements. Progress on internal coils and precision (co)magnetometers will also be discussed.
Speaker: Mr Michael Lang (The University of Winnipeg, The University of Manitoba)
Belle-II calorimeter endcap upgrade 15m
The improvement of the electromagnetic calorimeter endcap is the primary hardware contribution of Canada to the Belle-II experiment. The very high luminosity and large associated backgrounds dictate technology improvements required to ensure the performance fulfills the physics needs, despite these backgrounds. Meeting those challenging requirements will be achieved by replacing the crystals with pure Cs-I as well as changing the photo-detection technology and designing new signal conditioning and signal processing electronics. Validation of those technology choices based on simulations estimating the background level and the detector response will be discussed. Providing proper beam background shielding is an important consideration, which is assessed concurrently. The optimal geometries and materials for those shields are determined from Geant4 detector simulations and must balance conflicting space and performance requirements without compromising the endcap mechanical structure. The overall mechanical integration of all components in the enclosure designed for the previous Belle iteration will also be presented.
Speaker: Alexandre Beaulieu (University of Victoria)
(T1-3) Relativity and Gravitation - DTP / Relativité et gravitation - DPT FA-054
Convener: Prof. Arif Babul (University of Victoria)
Numerical simulations and analytical modeling of precessing binary black holes 30m
Advanced Gravitational Wave Detectors like Advanced-LIGO are expected to commence searches for gravitational waves as early as 2015. One of the prime sources for these instruments is the in spiral and coalescence of binary black holes. Numerical simulations of binary black holes play an integral role in this effort, and have matured now sufficiently to begin to address the most general case of spinning, precessing binary black holes. In this talk, I will describe recent successes of the SXS collaboration (CITA,Caltech,Cornell) to numerically simulate these systems, and to analytically model the resulting gravitational waveforms.
Speaker: Prof. Harald Pfeiffer (CITA, University of Toronto)
Black Holes in the Extreme 30m
Black holes are one of the most interesting theoretical predictions of general relativity. They arise as solutions to Einstein's equations which govern the classical gravitational field, generally described by a small number of parameters - mass, charge, and spin. A particular subset has recently attracted a great deal of attention: extremal black holes. For fixed mass, they are characterized by having the maximum spin and charge. There is good astrophysical evidence that they exist in our Universe. Further, they have zero temperature and do not suffer from the quantum mechanical instability of Hawking radiation. In short, they occupy a privileged position in a number of contexts. In this talk I will discuss the key properties of extremal black holes and some of the techniques used to understand them. In particular I will describe the notion of the near-horizon geometry of an extremal black hole. This gives us a precise representation of the black hole close to its event horizon, allowing us to study Einstein's equations in a simplified setting. Near horizon geometries provide us with the ability to analyze extremal black holes in a way not possible for general, non-extremal black holes. I will discuss a symmetry enhancement result for these geometries and progress made on their classification.
Speaker: Dr Hari Kunduri (Dept of Mathematics and Statistics, Memorial University)
Critical Phenomena in Higher Dimensional Spherically Symmetric Gravity 15m
String theory provides motivation to investigate critical phenomena in microscopic black hole formation in higher dimensional gravity theories. We investigate gravitational collapse in higher dimensional spherically symmetric Einstein and Einstein-Gauss-Bonnet (EGB) gravity. Our previous work has suggested the existence of a mass gap in odd dimensional EGB gravity. With adaptive mesh refinement code I have developed we are now able to investigate in more detail the possibility of such a mass gap as well as the difference in the scaling relation between even and odd dimensions. In addition, work on gravitational collapse in spherically symmetric anti-deSitter spacetime is being done.
Speaker: Mr Nils Deppe (University of Winnipeg)
Mass and Thermodynamic Relations for Lifshitz Symmetric Black Holes 15m
The definition of a meaningful thermodynamic mass (appearing in the first law and the Smarr relation, when a cosmological constant is taken into account) is a difficult concept in Lifshitz symmetric spacetimes, due in part to the boundary conditions that need to be satisfied. Knowing such a mass opens up opportunities for examining the critical behaviour of these black holes which is interesting in a gauge/gravity context. Here we discuss our attempts at formulating a mass for some exact Lifshitz symmetric black hole solutions.
Speaker: Wilson Brenna (University of Waterloo)
Weak Lensing in Modified Gravity: A 'Plug-and-Play' Approach 15m
At a time when understanding the accelerated expansion of the universe is one of the key questions of cosmology, we are compelled to examine the possibility of modifications to general relativity on very large scales. To do so, we consider the weak lensing power spectrum, for which deviations from the standard general relativistic form may be hallmarks of modified gravity. However, computing this quantity from scratch for each of the many theories of modified gravity can be intensive and inefficient. We consider instead linear-order deviations from general relativity and Lambda-CDM, motivated by the results of recent cosmological surveys. We hence construct an expression for the deviation of the weak lensing power spectrum from its general relativistic value, which has the form of an integral over two terms: a 'kernel', which is dependent only on GR+LCDM, and a 'source', which encompasses all deviations from this standard theory. This form provides a much more efficient way of computing the weak lensing power spectrum in each theory of gravity. It hence allows for easier comparison between theory and observation, as well as permitting more straightforward forecasting of constraints from upcoming surveys. I will discuss our derivation of this expression and demonstrate its application to illustrative modified gravity examples.
Speaker: C. Danielle Leonard (University of Oxford)
To Infinity and Back 15m
An interesting property of anti-de Sitter space is that massless fields can travel to infinity in a finite time, bounce back more focussed and collapse to form a black hole. This has recently been shown to lead to the instability of AdS against the formation of black holes. Our goal is to shed light on this by numerically examining the effect of adding higher curvature terms to the Einstein-Hilbert action. In the case of of 5-dimensional Einstein-Gauss-Bonnet gravity, for example, there exists a mass gap. That is, there appears to exist a minimum mass below which no black holes can form. It is of interest to see if this mass gap restores stability to AdS space in Einstein-Gauss-Bonnet gravity.
Speaker: Ms Allison Kolly (University of Winnipeg)
(T1-4) Mass Spectrometry and Nuclear Structure - DNP / Spectrométrie de masse et structure nucléaire - DPN C-114
Convener: Garnsworthy Adam (TRIUMF)
TITAN ion trap experiments for nuclear structure 30m
The TITAN (Triumf's Ion Trap for Atomic and Nuclear science) system is set up the ISAC rare beam facility at TRIUMF and enables precision experiments on very short-lived rare species. I present new measurements of atomic masses for nuclear structure in the so-called Island of Inversion, and for light Mg isotopes, where tests of the IMME were possible. The latter allowed for tests of the influence of three body forces in the theoretical description. Moreover, the ion trap system makes it possible to carry out decay studies of stored highly charged ions. These experiments are motivated by double beta decay searches and the need for bench-marking the theoretical framework of the transition matrix elements.
Speaker: Prof. Jens Dilling (TRIUMF/ University of British Columbia)
Multiple-Reflection Time-of-Flight Mass Spectrometry: from nuclear physics experiments to clinical applications 30m
Mass spectrometry is a technique, which was developed more than hundred years ago. It led to epochal discoveries and contributed to the foundation to what is now called nuclear and particle physics. Nowadays mass spectrometry is also applied as analytical tool in many directions of science, e.g. in chemistry, biology, geology, space science and many other fields. Time-of-Flight (TOF) mass spectrometry is one of the established methods, where ions are separated in a mass-dispersive flight path. The novel technique of Multiple-Reflection Time-of-Flight Mass Spectrometry (MR-TOF-MS), where ions are reflected multiple times between electrostatic mirrors enhances the range of applications. Arbitrarily long flight paths (typically of several 100 m) can be realized in compact systems (~ 1 m), resulting in a mass resolving power of several 100 000 as well as a mass accuracy of about 10^-7. MR-TOF-MS have been commissioned for rare ion beam facilities all around the world and are key devices of several projects. At GSI (Germany) a MR-TOF-MS performs direct ultra-high precision mass measurements of exotic nuclei and allows mass-selective decay spectroscopy. At TRIUMF (Canada) it will serve as an isobar separator to suppress isobaric beam contaminants and enable high accurate mass measurements of very short-lived products. A down-scaled, robust and mobile MR-TOF-MS opens up new applications in different fields e.g. in environment, climate research and in health, nutrition and security applications. In this way an instrument originally invented for nuclear physics experiments can contribute to modern medical diagnostics via fast (~ 1 s) detection of cancerous tissue in electro-surgery. In general, a new era of reliable analysis of breath gas can be made, as well as the microscopic composition of biological samples. Actual achievements and resulting opportunities with the novel method will be discussed in the present contribution.
Speaker: Mr Johannes Lang (II. Physikalisches Insitut, Justus-Liebig-Universität Giessen)
Absolute nuclear charge radii for elements without stable isotopes via precision x-ray spectroscopy of lithium-like ions 15m
There is currently no method to experimentally determine the absolute charge radius of nuclei for elements that have no stable or extremely long-lived isotope: The standard methods, electron scattering and muonic atom spectroscopy, require macroscopic amounts of the isotope under investigation. Thus, for nuclei with charge Z > 83, (uranium is the exception), there is no experimental data for the absolute nuclear charge radius. We are currently developing a technique to measure the absolute charge radius of any heavy isotope of sufficient half-life (order of seconds) using precise x-ray spectroscopy of the electronic 2s-2p transition in lithium-like ions. The finite nuclear size shifts the transition energy by more than 10 eV in these systems, whereas experimentally, the transition energy can be measured absolutely with an accuracy below 100 meV [1]. In addition, recent progress in QED theory allows us to account for radiative corrections at a comparable level as well [2]. As a result, the contribution by the finite nuclear charge distribution can be extracted at the 100 meV level. In this presentation, we will give details of our computational approach, and address prospects for future experiments. Supported by NSERC and the University of Manitoba. [1] P. Beiersdorfer et al., Phys. Rev. Lett. 80, 3022 (1998). [2] V.A. Yerokhin et al., Phys. Rev. Lett. 97, 253004 (2006).
Speaker: Mr Andrew Senchuk (University of Manitoba)
Gamma-ray spectroscopy in the vicinity of $^{100}$Sn 15m
The heaviest doubly-magic and self-conjugate nucleus $^{100}$Sn is known for its super-allowed Gamow-Teller decay with the smallest $\log ft$ value and providing experimental data for quenching effects and $rp$-process path models. In addition, $^{100}$Sn and its neighbouring species offer valuable insights for nuclear structure. Gamma-ray spectroscopy of $^{100}$Sn and nuclei in its vicinity with $N \simeq Z \simeq 50$ will probe single-particle/hole energies near the proton dripline, challenging current large-scale shell models in this $A$ and $Z$ region. The nuclei of interest were produced at RIKEN Rare Isotope Beam Factory in June 2013, where a high-intensity (36 pnA, $2.3 \times 10^{11}$ pps) $^{124}$Xe beam with 345 MeV/u energy was fragmented on a 4-mm Be target. The fragments were identified via energy loss, magnetic rigidity and time-of-flight measurements with BigRIPS and the ZeroDegree Spectrometer. In total, 2035 events of $^{100}$Sn were identified after 8.5 days of beamtime - the largest $^{100}$Sn yield to date by a factor of 8. Many other exotic nuclei with similar $A$ and $Z$ were produced,including previously unobserved species such as $^{98}$Sn and $^{96}$In. These nuclei were implanted in WAS3ABi, a set of position-sensitive silicon strip detectors which measured ion implantation position, $\beta^+$ particles' position and energy. Subsequent $\beta$-delayed gamma-rays were measured with the EURICA spectrometer featuring high-resolution/efficiency HPGe clusters and fast-timing LaBr$_3$ detectors. Of the more abundantly produced nuclei, the level scheme for $^{98}$Ag from the $\beta^+$-decay of $^{98}$Cd has been reproduced with new candidate transitions. Preliminary analysis and level schemes of exotic fragmentation species will be presented.
Speaker: Jason Park (University of British Columbia/TRIUMF)
Canadian Charged Particle Accelerator Consortium 15m
Many materials analysis techniques rely on the 'particle in - particle out' principle, where a source produces precisely controlled probe particles that interact with a sample and a detector characterizes the scattered or transmitted probe particles, providing information on the nature and structure of the sample under study. Examples of probe particles are electrons (electron microscopes), photons (synchrotrons), neutrons (indeed), and, in our case, ions. The Canadian Charged Particle Accelerator Consortium (CCPAC, http://ion.lps.umontreal.ca/) is a national facility, accessible for all Canadian and many international researchers, which provides ion beams for materials analysis and modification. In this contribution, we will present the suite of thin film analysis techniques available at CCPAC, showcase their strengths and limitations, and give some recent examples of analyses performed in aid of research in the field of physics of advanced materials.
Speaker: Sjoerd Roorda (U)
(T1-5) What we can do to help our students succeed in non-academic careers - DPE / Comment aider nos étudiants pour des carrières non académiques - DEP C-203
Convener: Barbara Frisken (Simon Fraser University)
What your advisor never told you: Education for the 'Real World' 30m
Studying physics (or any other subject...) because you love it is great. There are many career paths available to those who have studied physics, but there are skills, knowledge, and attitudes that physics education, by itself, doesn't typically provide to prepare students for the real world that they will enter – no matter what that career path may be. Entrepreneurship education is the key to bringing this content to physics students, with important benefits for all: Better preparation of students, greater ability to recruit students to the discipline, new opportunities for research projects, opportunities for partnerships, and, yes, the potential for financial reward. Carthage College created the ScienceWorks Entrepreneurial Studies Program in 1994 to address this issue and fill an education void. Now one of the leading programs in technical entrepreneurship, ScienceWorks is one model through which entrepreneurship education can be implemented. This talk will discuss some of the history of technical entrepreneurship education, the key components that such education includes, resources available to create and implement entrepreneurship education, describe a number of ways that it can be implemented at colleges and universities, and discuss the benefits that such a program will bring to the physics community.
Speaker: Dr Douglas Arion (Carthage College)
Easing the Transition of Physicists into Industry 30m
All physicists are told that physics is the foundation of subjects such as engineering. One might be led to believe that thus, finding a job as a physicist would be as easy, if not easier, than as an engineer. Sadly, this is far from the truth in the real world. Graduating with a degree in theoretical physics makes it even more difficult to get an industrial job - though, one may question why anyone in a theoretical stream would want a job in industry. The fact is that, things change. A student may one day find that though their efforts have been focussed on physics, theoretical or experimental, that life choices, or even changes of interest, can cause a rethinking of one's career. While it should be an easy transition from physics to an engineering job, or to a related technical field, the reality is that the outside world really does not know what physicists do, or what they are capable of doing. Human Resources departments are staffed with individuals looking for key words in resumes, with little or no understanding of how to match skills to job requirements. Many individual's resumes never make it to the hiring manager. This paper presents some thoughts on the subject of moving physicists from academia to industry, presented by someone with a degree in theoretical particle physics who has spent almost 25 years doing hardware design for the space industry. Recently, I've come to see a problem identical to my own career path where quantum physicists across Canada and particularly at the University of Waterloo's Institute for Quantum Computing have begun to tackle this very problem.
Speaker: Dr Ian D'Souza (COM DEV International Systems)
An Undergraduate Degree Program at the University of Windsor for Students Interested in a Non-Academic Career in Medical Physics 15m
The Department of Physics at the University of Windsor offers three streams within our B.Sc. Honours Physics degree program: General Physics, Physics and High Technology, and Medical Physics. Of these programs, the latter two are both targeted specifically toward students interested in non-academic careers (NAC). As of the Fall of 2013 these students comprised 57% of the undergraduate physics student population. In this talk I will describe our relatively new medical physics stream (the largest stream in the Department), including our motivation for starting this stream, the specific career education and experiential learning opportunities afforded our students, our expectations for these students after graduation, and the career progress made by our graduates so far.
Speaker: Steven Rehse (University of Windsor)
Panel discussion – "What can we do to help our students succeed in non-academic careers?" 45m
(T1-6) Quantum Optics - DAMOPC / Optique quantique - DPAMPC C-301
Convener: Jack Sankey (McGill University)
Effects of Time Ordering in Parametric Down-Conversion and Frequency Conversion 15m
Parametric down-conversion (PDC) and frequency conversion (FC) are two of the most common nonlinear processes used in quantum optics. In the first process a nonlinear crystal is used to down convert photons from a pump laser into pairs of photons correlated by energy and linear momentum conservation constraints. In the second process, the frequency of photons is increased or decreased after interaction with a strong pump field inside a nonlinear crystal. These two processes share the property that the Hamiltonian that governs them does not commute with itself at different times and hence time ordering becomes an important aspect in the description of their dynamics. The two processes also share the attribute that whenever the pump photons are prepared in a coherent state with an amplitude that can be assumed un-depleted during the time evolution, the Hamiltonian is quadratic in the bosonic operators of the down-converted or frequency converted photons. This property implies that the dynamics of the system is ``Gaussian preserving'' and that the output state of spontaneous PDC is, even when time ordering is considered, a two mode squeezed vacuum. In this work we study the effect of time ordering in PDC and FC using the Magnus expansion. The Magnus expansion approximates the time evolution operator as the exponential of the Magnus series $U_{\text{Magnus}}= \exp( \Omega_1+ \Omega_2+\Omega_3+\ldots) $. We obtain analytic approximations to the evolution operator that are unitary and Gaussian preserving and that allow us to understand order-by-order the effects of time ordering. We contrast our perturbative solution with the more common Dyson series solution $U_{\text{Dyson}}= I+ T_1+T_2+T_3+\ldots $ which is not able of preserving the Gaussian form or unitarity at any finite order and thus leads to unphysical results. We also calculate the effects of time ordering in the Joint Spectral Amplitude (JSA) of the photons generated in spontaneous PDC and show that even in the case when the phase matching and pump functions are real the JSA becomes complex because of time ordering. Finally, we show that whenever the phase matching function is broad enough the corrections due to time ordering vanish exactly.
Speaker: Nicolas Quesada (University of Toronto)
Improved quantum light generation in optical fibres through incoherent nonlinear optics 30m
Entangled photons are a very useful resource for quantum optics experiments. Entanglement is usually obtained through nonlinear parametric effects, such as modulation instabilities in optical fibres. We show that the coherence properties of the pump laser greatly affects the efficiency of third-order parametric effects. We present a model for incoherent nonlinear processes in optical fibres and demonstrate how the use of an incoherent pump leads to improved quantum sources.
Speaker: Stephane Virally (Ecole Polytechnique de Montreal)
From classical to quantum nonlinear optics in photonic structures 30m
Nonlinear polarizations described by the χ(2) and χ(3) susceptibilities are central to many of the phenomena of classical nonlinear optics, including processes as diverse as second harmonic generation and four-wave mixing. These same susceptibilities govern quantum optical processes in which correlated photons are generated, such as spontaneous parametric down-conversion and spontaneous four-wave mixing. We argue that it is useful to address classical and quantum calculations within the same framework, particularly in the integrated optics structures that will be important for quantum information processing "on a chip." When this is done a more unified picture of nonlinear optics, involving both classical and quantum regimes, results; we show how analytical or numerical classical calculations, or even just the results of classical experiments, can immediately be used to predict the behavior of a device in the quantum regime, and how it will scale as parameters are changed. We also show how it is possible to do a "virtual tomography" of the entangled states that would be generated in a quantum experiment by recording the results of a series of easily-performed classical experiments.
Speaker: Prof. John Sipe (Department of Physics, University of Toronto)
Good Vibrations: Ultrafast Quantum Processing in Molecules 30m
Speaker: Prof. Benjamin Sussman (National Research Council)
Quantum Control of Wave-Particle Duality 15m
Wave-particle duality, superposition and entanglement are among the most counterintuitive features of quantum theory. They clash with conventional classical wisdom and motivate the construction of hidden-variable theories. Here I point out that realism (defined as a property of photons being either particles or waves, but not both) is incompatible with determinism provided superluminal communication is forbidden. This places severe constraints on HV theories, which in turn can be subject to experimental tests using quantum delayed-choice experiments.
(T1-7) Quantum Materials - DCMMP / Matériaux quantiques - DPMCM A-226
Convener: Young-June Kim (U)
Terahertz-frequency test for Fermi liquid conductivity in MnSi 30m
Fermi liquid theory predicts that electron-electron scattering will contribute $\rho_{e-e}(\omega,T)=A \left[(\hbar\omega)^2+b(\pi k_B T)^2 \right]$ to the frequency-dependent resistivity of any metal at low temperatures and frequencies. In its simplest form, the theory further predicts that the temperature and frequency dependence are related by $b=4$, but numerous experimental studies have yielded $b\approx 1$ for different metals, and none have observed the predicted value. I will review progress in understanding this issue, with an emphasis on our measurements on MnSi with terahertz time-domain spectroscopy. As with other metals, the resistivity exhibits the quadratic frequency dependence predicted by Fermi liquid theory, but with $b\approx 1$ over a wide range in temperature. At the lowest temperatures, we observe evidence for a crossover to $b\approx 4$, although this is currently limited by a large systematic uncertainty that we will discuss. Additionally, we have determined the Drude scattering rate and plasma frequency at low temperatures, and compared these to realistic band theory calculations. Above a coherence temperature $T_{coh}\approx 50$ K, we find evidence for the existence of a pseudogap. Below $T_{coh}$, $\tau$ increases dramatically to $\tau\approx 0.5$~ps at $T\approx 5$~K. From a comparison of the low-temperature plasma frequency measurement with band theory, we determine a mass renormalization of $m^*/m \approx 5.5$, which compares favorably with earlier quantum oscillation measurements.
Speaker: J. Steven Dodge (Simon Fraser University)
How density of states singularities found in the Anderson model evolve with the addition of electron-electron interactions 15m
The influence of disorder on correlated electron systems remains poorly understood. Recent work [1], [2] by Johri and Bhatt shows singular behavior in the density of states (DOS) of non-interacting disordered systems. This is surprising because there was a significant and unsuccessful effort to find a singularity in the DOS after Anderson's prediction of localization in 1958. Furthermore, in two-site systems the singularity marks a transition to an energy range where the DOS contribution comes from pairs of sites with similar potential called resonant states. We are studying how the addition of electron-electron interactions affects this singularity in the DOS. We find that the singularity persists at lower interaction strengths and new singularities appear at higher values. We examine how these DOS features correlate with the resonant states present in two-site interacting systems. [1] Johri, S., Bhatt, R. N., Singular behavior of eigenstates in Anderson's model of localization, Physical Review Letters 109, 7, 076402 (2012) [2] Johri S., Bhatt R. N., Singular behavior of Anderson localized wave function for a two-site model, Physical Review B 86, 12, 125140 (2012)
Speaker: Jayanayana Perera
Entanglement entropy in quantum fluids and gases 30m
We present a scalable algorithm for computing Rényi entanglement entropies in systems of itinerant bosons in the spatial continuum via quantum Monte Carlo. This method is applicable to the study of spatial mode entanglement, particle partitioned entanglement, and the entanglement of particles under a spatial partitioning. We demonstrate its utility by studying a non-trivial interacting Bose gas in one spatial dimension where we uncover a logarithmic scaling of the entanglement entropy in the number of particles and confirm bounds on it related to the experimentally measurable condensate fraction. For the first time, this method opens up the numerical study of quantum correlations in experimentally relevant quantum fluids such as helium-4 and cold atomic gases.
Speaker: Adrian Del Maestro (University of Vermont)
(T1-8) Surfaces and Thin Films - DCMMP-DSS / Surfaces et couches minces - DPMCM-DSS C-304
Convener: Mark Gallagher (Lakehead University)
Transition Metal Oxides based Chromogenic Thin Films and Interactive Devices 30m
Transition metal oxides (TMO) with their metastable multiple oxidation states offer a wide range of optical and electrical switching properties. Chromogenic materials are characterized by their ability to undergo a reversible change in their optical properties under the application of a small external force in the form of heat, light or an electric field. Hence, TMO based chromogenic materials and devices have become the object of an intense research ,lately, in photonics and communications area. Through a small activation energy applied in different forms, one can drive these systems from one metastable state to another with large variation in their optical and electrical properties. By preparing these materials in thin film form, interactive optical (transmittance, reflectance and absorption) and electrical switching devices with facile operation can be constructed with a highly versatile control of these properties. In addition, these switching properties are found to depend extremely sensitively on the film nanostructure. Much of the present work in this area is focussed on the methodology of a controlled inducing of the nanostructure in these films and their devices to increase their switching contrast. Hence, these materials are of immense importance both from the underlying physics and chemistry point of view as well as from the application point of view. A review of the state of development of this field in terms of the physics of these materials and their development towards application in photonics and communications will be presented. The work being carried out in our Thin Films and Photonics Research Group (GCMP) laboratories at Université de Moncton will also be discussed.
Speaker: Prof. Pandurang Ashrit (Université de MOncton)
Ordered supramolecular polythiophene structures on passivated silicon surfaces. 15m
The functionalization of semiconductor surfaces with organic molecules is a necessary step in the development of hybrid organic-semiconductor structures. A significant challenge to organic layer formation is the fact that semiconducting surfaces exhibit a large number of dangling bonds which suppress the diffusivity of adsorbed molecules and can even break the molecules apart via the formation of Si-C bonds. Recently it has been shown that these problems can be obviated by depositing the molecules onto a passivated surface [1]. We have studied the adsorption of brominated tetrathienoanthracene molecules (TBTTA) onto the Si(111)-√3×√3-Ag surface. Thiophene based molecules like TBTTA are of considerable interest in organic semiconductor research due to their efficient conjugation and the chemical stability [2]. The Si(111) √3×√3-Ag surface has no Si dangling bonds and should provide a high mobility surface suitable for TBTTA adsorption. Scanning Tunneling Microscopy images reveal that at low coverage the molecules readily migrate to step edges and defects in the √3 overlayer, in fact many images show direct evidence of molecular mobility. With increasing coverage the molecules eventually form compact supramolecular structures. In terms of the √3 lattice vectors (a and b), the oblique unit cell of the supramolecular structures is am = 3a + b, and bm = a + 2b. These structures are quite fragile and can decompose under repeated STM imaging. Our results suggest that TBTTA is weakly bound to the √3 surface at room temperature and that the supramolecular structures are held together by weak van der Waals forces. 1. T. Suzuki et al., Phys. Chem. Chem. Phys. 11 , 6498–6504 (2009). 2. R. Gutzler et al., Nanoscale 6, 2660-2668 (2014).
Speaker: Mr Renjie Liu (Lakehead University)
Facile nucleation of gold nanoparticles on graphene-based thin films from Au144 molecular precursors 15m
We demonstrate a facile and cost effective method to obtain gold nanoparticles on graphene by dispersing Au144 molecular nanoclusters by spin coating them in thin layers on graphene-based films and subsequent annealing in a controlled atmosphere. The graphene-based thin films used for these experiments are prepared by solvent-assisted exfoliation of graphite in water in the presence of ribonucleic acid as a surfactant and by subsequent vacuum filtration of the resulting graphene-containing suspensions. Not only is this method easily reproducible, but it leads to gold nanoparticles that are not dependent in size on the number of graphene layers beneath them. This is a distinct advantage over other methods. Plasmonic effects have been detected in our gold nanoparticledecorated graphene, indicating that these thin films may be useful in applications such as plasmonic solar cells and optical memory devices.
Speaker: Andrei Venter
Atomistic Studies of Semiconductor Nanowires 30m
Semiconductor nanowires (NWs) are quasi-one-dimensional nanostructures that have sparked a surge of interest as powerful and versatile building blocks for an extended range of emerging nanoscale technologies. These novel technologies exploit size-related effects, the flexibility in the fabrication and design offered by the use of NWs, and the concomitant progress in probing nanoscale properties. In this presentation, we will focus on NWs synthesized through VLS/VSS modes. More precisely, we will discuss the current understanding and technological implications of defect engineering and impurity incorporation into these NWs. The phenomenon of mass transport at the catalyst-nanowire interface will be elucidated. Particularly, catalyst atoms injection and trapping in NWs will be addressed. This phenomenon implies atoms detachment from the catalyst and their injection into the growing nanowire thus involving atomic scale processes that are crucial for the fundamental understanding of the catalytic assembly of nanowires. Herein, we present an atomistic level and quantitative study of this phenomenon of catalyst dissolution by three-dimensional atom-by-atom mapping of individual silicon nanowires using highly focused ultraviolet laser-assisted atom-probe tomography. This catalytic doping is described using a model of solute trapping at step edges and the key growth parameters are identified based on a kinetic model of step-flow growth of NWs. The control of this phenomenon provides myriad opportunities to create entirely new class of nanoscale devices by precisely tailoring shape and composition of metal-catalyzed nanowires.
Speaker: Oussama Moutanabbir (Ecole Polytechnique de Montreal)
(T1-9) Medical Imaging II - DMBP / Imagerie médicale II - DPMB C-204
Convener: Melanie Martin (University of Winnipeg)
Preliminary results of a Beam Expander for Biomedical Imaging 15m
X-ray phase based imaging is becoming increasingly important due to the high contrast that can be obtained from soft tissues. A number of synchrotron facilities use phase contrast routinely for imaging of biomedical systems. One of the simplest and most used phase contrast method is in-line or propagation based phase contrast. Due to the small beam size available from synchrotron sources there are significant limitations on the physical size of objects that can be imaged without scanning the object through the beam. This severely limits the applicability of synchrotron sources for imaging systems in real time. We present results of a bent Laue beam expanding double crystal monochromator for use at the Biomedical Imaging and Therapy (BMIT) beamlines at the Canadian Light Source. This system will enable live animal dynamic imaging not previously possible at this facility, as well as drastically reduce image acquisition and processing time for work already being done. Previous experiments led us to an expansion of 7.7x the incident beam height, however the loss of beam coherence seriously limited its usability for phase-dependent imaging techniques. Recent improvements to the system have increased this expansion to 12x while maintaining phase coherence. Implementation of this expander in the insertion device (wiggler) beamline at BMIT has the potential to bring this facility to the forefront of biomedical synchrotron imaging facilities worldwide.
Speaker: Mercedes Martinson (U)
CARS microscopy of cancer cells in vitro and tumors in vivo. 15m
Identification of cancer cells in tumors is still a challenge in the biomedical field. Coherent Anti-Stokes Raman Scattering (CARS) microscopy may be useful for fast retrieval of 3D imaging and to distinguish cancer cells from the non-cancerous environmental cells as it is a label-free imaging technique that is capable of real-time, non-pertubative examination of living cells and organisms based on molecular vibrational spectroscopy with a sub-micron spatial resolution. In this project, we have taken CARS and Second Harmonic Generation (SHG) images of normal and cancer cells using a optical setup developed in collaboration with Genia Photonics. Epithelial cancer cells (HT29 and MCF-7) and normal epithelial cells (MCF-10A) were embedded in 300µm-thick collagen gel laid on glass coverslips and then observed directly on a microscopic platform equipped with a 20X objective. Control observations were done with fixed (formaldehyde) and stained (dyes and fluorescent probes) specimens. Tumor xenografts were induced after injection of cancer cells (HT29) in mouse spleen (lymphoid tissue) to reproduce lymph node metastases. Cryosections (20-30mm thick) of retrieval and unfixed tissues were performed to allow direct CARS and SHG microscopy through a glass coverslip. Routine histology sections were used to compare imaging. Resulting 3D cell morphology was close to that seen by optical microscopy. Cancer cells were also seen in tissue sections of lymphoid tissue-grafted tumors for which imaging was clearly distinguishable from the inflammatory reaction and fibrotic reaction (observed with SHG) as well as the normal lymphoid tissue.
Speaker: Mathieu Laliberté (I)
Medical radioisotopes made at TRIUMF: Accelerating medicine for Canada 30m
One of TRIUMF's main objectives is to develop isotopes for use across applications in science and medicine. The nuclear medicine division has a long history of producing short-lived F-18 and C-11 as Positron Emission Tomography (PET) tracers for the Pacific Parkinson's Research Centre. Recently, we have expanded to investigate the production of isotopes to help address looming shortages of important clinical isotopes and promising new isotopes that are of increasing interest to chemists, biologists and medical researchers. Herein, we present the status of our Tc-99m effort, which is used in 20-40 million nuclear medicine procedures worldwide every year. Typically, Tc-99m is made available via a generator through the beta decay of Mo-99, which originates from nuclear reactors. Canada has played a pivotal role in the Mo-99 supply with a capacity of producing 80% of the world's demand with the NRU nuclear reactor but due to its planned shutdown in 2016 an alternative production method is needed. TRIUMF in collaboration with other Canadian institutions is leading the effort to produce Tc-99m directly on a small cyclotron via the Mo-100(p,2n) reaction. Recent successes have seen 10 Ci (370 GBq) of Tc-99m produced, enough to supply the Greater Vancouver area. Proton-induced cyclotron production of radiometallic isotopes requires the irradiation of solid material, mandating non-trivial upgrades to most medical cyclotrons. We are investigating the use of liquid targets to produce radiometals in order to increase their availability to the medical community. With this new approach, we hope to open the door for the development of novel PET. To date, Ga-68, Zr-89, Sc-44, Y-86, and Cu-61 have been demonstrated. Finally, a brief discussion will ensue on TRIUMF's efforts to apply our ISOL technique for the isolation of radiotherapeutic isotopes at the ISAC facility at TRIUMF. Progress on the isolation of At-211 (via Rn-211 decay) and At-209 (via Fr-213) will be presented. At-211 is an alpha emitting isotope with the potential to treat malignancies such as leukemia. At-209, a gamma-ray emitter, can be used together with At-211 to follow its progression through and accumulation in the body. At-209 was produced and separated to perform the first successful phantom images on a SPECT camera, demonstrating it to be a new promising asset for cancer therapy research.
Speaker: Cornelia Hoehr (TRIUMF)
Second Harmonic Generation (SHG) microscopy of articular cartilage to image collagen modifications caused by osteoarthritis. 15m
Osteoarthritis is a debilitating and painful disease involving the dysfunction and degradation of joint tissue. It affects mainly the knees and the hips and the most widely recognised change in the cartilage is the loss of the proteoglycans and the degradation of the articular cartilage. The irreversible stage of this degeneration is thought to be damage to the collagen type II meshwork, which leads to a cascade of degradation. No cure has been found yet to treat osteoarthritis and when the degradation is too advanced, the only solution is the replacement of the joint. The collagen type II is a protein that has a noncentrosymmetric structure that allows the generation of second harmonic signal. Therefore, second harmonic generation (SHG) microscopy is an ideal technique for high spatial resolution imaging of cartilage. Here, we use SHG microscopy to image the modification of the collagen structure on the surface of articular cartilage and in the deep cartilage matrix. Thick slices of cartilage taken from bovine knee have been used to image the surface of cartilage. In samples taken from diseased knee near localised eroded regions, many structures associated with osteoarthritis has been found. Among them, we found progression of degradation front, entanglement of the collagen matrix and formation of collagen bundles. Using thin sections of human tissue with early stage disease, we have measured the SHG intensity and the polarisation dependence of the signal in deep cartilage matrix in the forward and in the backward direction. Forward refers to the direction of laser propagation while backward is at 180 degrees. By imaging these tissues, we found regions of high forward SHG signal in which the polarization angle at maximum amplitude sometimes differs from elsewhere in the tissue. While the signal in the diseased regions in the forward direction significantly increases, the signal in the backward direction only slightly decreases. Also, the modification of the angle of the polarisation in which the signal is maximum in the backward direction remain the same as elsewhere in the collagen meshwork, unlike what has been observed in the forward direction. Our studies reveal that SHG microscopy is a powerful technique to image the collagen structure in articular cartilage and allows probing the early stages of osteoarthritis.
Speaker: Marie-Andrée Houle (INRS)
A Method for Coincidence-Compensation for an MCNP Simulation of a Co-60 Volume Source and Detector 15m
A Monte-Carlo simulation via the MCNP computer program is a convenient method of indirect detector calibration when a direct calibration is not feasible. This is the case when very-short-lived gaseous radioactive sources are involved. Before being relied on, the MCNP model is normally validated with commercially available calibrated radioactive sources. This presentation will discuss the steps to compare an MCNP output with a real energy spectrum acquired with a Multi-Channel Analyzer (MCA). The detector in this case is a 1.5"x1" NaI scintillator. The source used for the validation test is Co-60. A large discrepancy between the MCNP-predicted output and the MCA measurement was noticed during the validation. There is no data from MCNP above the 1.33 MeV photo-peak from Co-60. Analysis indicates that the discrepancy is caused by the coincidence summing effect which becomes significant when the detector has a large solid angle for the source. After assuming homogeneous spatial distribution of the gamma photons, a method is developed to simulate the coincidence summing effect. Starting with a point source case, a volume source compensation method is developed. The compensated MCNP output is compared with the real measurement. The MCNP output range is extended to 2.51 MeV in good agreement with the MCA spectrum. The result confirmed the correctness of the geometry and material configuration of the MCNP model.
Speaker: Bryan van der Ende (Atomic Energy Canada Ltd.)
Inferring sub-micron sizes using oscillating gradient diffusion weighted magnetic resonance imaging 30m
We have developed a new method for distinguishing the size of submicron structures using diffusion weighted magnetic resonance imaging (MRI). This method relies on MRI signal changes because water in samples undergoes diffusion. The mean-square displacement of the water molecules depends on the diffusion time. Molecules diffusing in a uniform medium with no barriers experience unrestricted diffusion. In non-uniform media (e.g. porous samples and cellular tissues) barriers hinder or restrict molecular displacements so that the diffusion depends on the time scale of the study, on the size of pores, and on the permeability of the barriers. The method relies on probing the shortest possible diffusion time scales so that the transition from restricted to hindered diffusion within the smallest structures can be detected. Current state-of-the-art methods cannot distinguish these small structures because current methods use pulse sequences which limit the ability to probe the shortest diffusion times. Our method circumvents those limitations by using oscillating gradients in place of pulsed gradients. The new method has important biological and neuroscience applications; one example is probing axon diameter distributions. In this talk I will summarize the method and our improvements to other methods for determining axon sizes. I will discuss our Monte Carlo simulations using cosine gradient spin echo sequences and the ability of our method to infer submicron sizes. Improvements to the speed of the simulations were made using GPUs instead of CPUs. I will also show our MRI data collected from micron-sized polystyrene beads on our Bruker 7 T 21 cm scanner using three of the OGSE sequences (sine, double sine, and apodised cosine). This method has opened a new era of MRI with sensitivity of submicron scale structures. The method can be adapted to other systems, biological or otherwise. Combining our method with other methods sensitive to large scales will allow us to distinguish a large range of restriction sizes from very small to fairly large and give a more complete understanding of the geometry of the sample. Funding NSERC, MHRC, CFI, CIHR and MRIF.
Speaker: Melanie Martin (University of Winnipeg (Physics) and Manitoba (Radiology, Physics & Astronomy))
CAP Teachers Workshop (Day I) / Atelier des enseignants (Jour 1) F-536
CAP Foundation Board Meeting / Réunion du c.a. de la Fondation de l'ACP F-335
Health Break (with exhibitors) / Pause santé (avec exposants) Alumni Hall + Foyer
(T-MEDAL1) CAP Medal Talk - Ian Affleck, UBC (Brockhouse Medal Recipient/Récipiendaire de la médaille Brockhouse) FA-054
From String Theory to Quantum Dot Experiments 30m
The string theory revolution of the 1980's led to remarkable developments in quantum field theory in one space and one time dimension. With my collaborators we developed this theory to predict exact results on the low energy behaviour of various quantum impurity models in condensed matter physics. Some of these predictions were verified recently in experiments on gated semi-conductor quantum dots.
Speaker: Ian Affleck (University of British Columbia)
(T-MEDAL2) CAP Medal Talk - Melanie Campbell, U. Waterloo (CAP-INO Medal Recipient for Outstanding Achievement in Applied Photonics / Récipiendaire de la médaille de l'ACP-INO pour réalisations exceptionelles en photonique appliquée) FA-056
Through the optics of the eye to a window on the brain 30m
Measurements of the optical quality of the eye have increased in precision and repeatability as a result of adaptive optics techniques adapted from astronomy. We have used these techniques to identify signals to the direction of eye growth which are up regulated in the presence of myopia (short-sightednesss), induced by defocussing lenses. These and other optical changes measured in myopia have led to a greater interest in the role of the optics of the eye in understanding and treating myopia. As well as measuring the optical quality more precisely, we can correct optical blur and acquire high resolution in vivo images of individual retinal cells. We are using this instrumentation to explore the earliest ocular changes in Type I diabetes and changes in degenerative diseases affecting the photoreceptors of the human eye. This may lead to earlier and improved interventions in these diseases. I will also briefly discuss the potential use of precisely focussed light in the treatment of ocular disease. Currently, definitive diagnosis of Alzheimer's disease only occurs after death. Amyloid beta, a protein marker which produces plaques is found in the brains of those with the disease. Recently we have confirmed the presence of amyloid beta in the ex vivo neural retina of those with the disease and not in age matched normal subjects without the disease. We are developing an in vivo polarization imaging technique which we hope will become a more accessible, less invasive and less expensive technique than others under development for the diagnosis of Alzheimer's disease.
(T-MEDAL3) CAP Medal Talk - Mark van Raamsdonk, UBC (CAP-CRM Prize in Theoretical and Mathematical Physics Recipient / Récipiendaire Prix ACP-CRM en physique théorique et mathématique) FA-054
Gravity and Entanglement 30m
The AdS/CFT correspondence from string theory provides a quantum theory of gravity in which spacetime and gravitational physics emerges from an ordinary non-gravitational system with many degrees of freedom. In this talk, I will explain how quantum entanglement between these degrees of freedom is crucial for the emergence of a classical spacetime, and how Einstein's equations can be derived at the linearized level from the dynamics of quantum entanglement.
Speaker: Mark Van Raamsdonk (University of British Columbia)
CAP Past Presidents' Lunch / Dîner des anciens présidents de l'ACP Time and L-303 (Faculty Lounge)
L-303 (Faculty Lounge)
DAMOPC Annual Meeting / Assemblée annuelle DPAMC F-336
Convener: Francois Legare (INRS-EMT)
DMBP Annual Meeting / Assemblée annuelle DPMB F-335
DNP Annual Meeting / Assemblée annuelle DPN F-337
DPP Annual Meeting / Assemblée annuelle DPP F-443
Convener: Chijin Xiao (Univ. of Saskatchewan)
Lunch / Dîner
(T2-1) Theoretical Astrophysics - DTP / Astrophysique théorique - DPT C-309
Convener: Robert Mann (University of Waterloo)
Non-linear Cosmological Structure Formation: Outstanding Questions and Future Prospects 30m
While the fundamental parameters of cosmology, such as the energy density of dark energy, dark matter, and baryons are now known to considerable precision, the precise interplay between these sectors in the "late" Universe is still the subject of extensive research. Nowhere is this more intense than in the study of non-linear structures, such as galaxies, clusters of galaxies and even the first stars. The absence of analytical solutions, and the need for detailed predictions to compare with observations, has precipitated almost an exponential increase in the use of simulation methods in research on cosmological structure formation. Much of the focus of these explorations is on understanding how luminous matter, most often stars although radiative processes in gas are also considered, evolves within this coupled gravito-radiation-hydrodynamics problem. To make matters more complex, in last ten years it has also become clear that "supermassive" black holes have a significant role to play in the evolution of the largest galaxies. I will present a non-specialist overview of the current state of the field and highlight some of the truly challenging research questions currently being tackled, as well as the prospects for solving them.
Speaker: Robert Thacker (S)
Testiing Black Hole Physics with the Event Horizon Telescope 30m
The Event Horizon Telescope, a millimetre-wave Earth-sized interferometer, provides unprecedented access to the physics and astrophysics of supermassive black holes. Already observed, the black holes at the centres of the Milky Way and the giant elliptical galaxy M87 provide a glimpse into the mechanisms of accretion, relativistic jet formation, and even the nature of black holes themselves. I will discuss how interpreting these observations within a highly successful theoretical framework and broader observational context has allowed us to begin to answer some of the fundamental questions in black hole science, including the nature of low-luminosity accretion flows, the role of spin in powering relativistic outflows, and structure of spacetimes around astrophysical black holes.
Speaker: Prof. Avery Broderick (University of Waterloo, Perimeter Institute for Theoretical Physics)
Analytic derivation of the substellar mass limit for a non-zero degeneracy parameter 15m
We develop an analytic formulation to find the internal structure of sub-stellar objects. This yields a value for a minimum stellar mass that denotes the boundary between brown dwarfs and stars. Our method employs an exact expression for the pressure of an ideal non-relativistic Fermi gas at finite temperature, meaning that the parameter $\psi$ is non zero. Our model gives a more accurate pressure than using the purely degenerate ($\psi =0$ ) limit. Integration of the Fermi distribution to yield an equation of state can be accomplished using the polylogrithm functions. This equation of state is used to solve the Lane-Emden equation to obtain the surface luminosity of a brown dwarf. On equating it with the luminosity for nuclear burning we find the maximum mass for a brown dwarf, $0.07M_o$. This result is in agreement with the results of the numerical models, but it is simple and provides maximum insight into the physics.
Speaker: Mr Sayantan Auddy (Student)
(T2-10) Neutrinoless Double Beta Decay - DNP-PPD / Double dégénérescence beta sans neutrino - DPN-PPD FA-054
Convener: Shelley Page (University of Manitoba)
Search for Neutrinoless Double Beta Decay with EXO 30m
The EXO collaboration continues to search for the neutrinoless double beta decay of 136Xe. Discovery of this process would lead to a new understanding of neutrino properties and provide a first measurement of the neutrino mass scale. The collaboration is currently operating a 200 kg liquid xenon time projection chamber, EXO-200, at WIPP in New Mexico. A detailed description of the experiment will be provided along with the latest results from EXO-200. Efforts are also underway to develop a 5-tonne scale detector. Details of this project will be presented in the context of the longer-term efforts to understand and measure properties of the neutrinos.
Speaker: Caio Licciardi (Carleton University)
Neutrinos at SNOLAB: SNO+ and HALO 30m
SNOLAB is the facility of choice for the next generation of underground particle astrophysics experiments. The scientific programme of SNOLAB encompasses the search for neutrino-less double beta decay; low energy solar neutrino studies; the neutrino signal from the next galactic supernova; and the quest for the direct observation of dark matter. This talk leaves aside the several SNOLAB experiments focussed on dark matter and describes the elements of SNOLAB's neutrino programme by presenting the physics potential and the status of the SNO+ and HALO experiments. SNO+ is the successor experiment to the Sudbury Neutrino Observatory (SNO) that re-uses much of the SNO infrastructure to create a multi-purpose kilotonne liquid scintillator detector. By replacing SNO's heavy water target with liquid scintillator SNO+ can substantially lower its energy threshold and improve its energy resolution which opens several possibilities to contribute to neutrino physics. The highest scientific priority is placed on the search for neutrino-less double beta decay in Te-130. An unambiguous observation of which would establish the Majorana nature of the neutrino and indirectly constrain the absolute neutrino mass. This phase of SNO+ operation will initially involve the loading of the liquid scintillator 0.3% by weight of natural Tellurium. In other operational phases, without Te loading, SNO+ would be able to measure the low energy part of the solar spectrum; measure the flux of anti-neutrinos associated with the radioactivity in the earth's crust; measure neutrino oscillation parameters by detecting the anti-neutrinos from Ontario's reactors. In all phases of operation SNO+ will be sensitive to a burst of neutrinos from a galactic supernova and by participating in the Supernova Early Warning System (SNEWS), along with HALO, help to ensure that astronomers also derive maximum benefit from such a rare opportunity. Unlike SNO+, the Helium and Lead Observatory (HALO) is dedicated to a single objective, that of recording data from the next galactic supernova. HALO employs 80 tonnes of lead as its neutrino target and Pauli blocking in the lead nucleus makes HALO dominantly sensitive to electron neutrinos in contrast to anti-electron neutrinos, which is the case with both Cerenkov and liquid scintillator based detectors, positioning HALO to make a unique contribution.
Tellurium Preparation for the SNO+ Neutrinoless Double Beta Decay Search 15m
SNO+ is a kilotonne-scale liquid scintillator neutrino experiment that is currently being constructed at SNOLAB. One of the primary physics goals of SNO+ will be a search for neutrinoless double beta decay, which will be carried out by loading tellurium metal into the liquid scintillator. This talk will describe the techniques that have been developed to prepare tellurium for use in SNO+, most notably techniques to reduce radioactive impurities in the tellurium to extremely low levels.
Speaker: Alex Wright (Q)
Measurement of the Pion Absorption and Charge Exchange Cross Sections for the T2K Experiment 15m
In T2K, neutrinos are observed via charged current quasi-elastic scattering (CCQE) interactions (\nu_{\mu}+n->\nu^{-}+p), as well as charged current single pion production (CC1\pi) (\nu_{\mu}+p->\mu^{-}+p+\pi^{+}). The \pi^{+} is free to interact inside and outside the nucleus via absorption (ABS) and charge exchange (CX: \pi^{+}->\pi^{0}) processes. If there is an unobserved pion, then the reconstructed neutrino energy is incorrect. Reducing the uncertainties on these cross-sections reduces the systematic uncertainties for neutrino oscillation measurements. The DUET Experiment was conducted in the M11 \pi^{+} beam line at TRIUMF to address this issue. Both combined ABS+CX and separate CX cross section measurements for \pi^{+} with initial momentum in the range of 200~350 MeV/c will be presented. The impact of this measurement for oscillation analyses on T2K and future experiments will be discussed.
Speaker: Elder Pinzon (Y)
(T2-2) Nuclear Physics, Heavy Ions, Extreme Matter - DNP / Physique nucléaire, ions lourds et matière extrême - DPN C-203
Convener: Michael Gericke (University of Manitoba)
Experimental Update of the TIGRESS HPGe Clover Array 30m
Philip J. Voss* on behalf of the TIGRESS Collaboration *Department of Chemistry, Simon Fraser University, Burnaby, BC, Canada V5A 1S6 Radioactive isotopes far from the valley of beta stability exhibit a variety of interesting properties. Quantifying the evolution of nuclear structure with increasing proton-neutron asymmetry is a major focus of current experimental efforts. High precision gamma-ray spectroscopy plays an important role in this pursuit and provides fundamental probes of nuclear structure and stringent tests for theoretical models important to our understanding of these many-bodied systems. As such, the high-efficiency and Compton-suppressed segmented germanium clover detector array TIGRESS is the key driver for the in-beam gamma-ray spectroscopy program at TRIUMF, where accelerated radioactive beams from the ISAC-II facility permit access to nuclear structure information for a wide range of exotic isotopes. Several sophisticated ancillary detector systems enhance the sensitivity of gamma-ray spectroscopy and provide additional experimental observables. These devices couple to the TIGRESS experimental infrastructure, resulting in a highly specialized and quickly reconfigurable experimental facility for nuclear structure studies. In particular, two highly-segmented, double-sided silicon detector arrays have been used for transition rate studies of 11Be using low-energy Coulomb excitation (BAMBINO) and single-particle structure measurements using (d,p) transfer reactions with 94Sr as the first accelerated high-mass radioactive ion beam delivered by ISAC-II (SHARC). In addition, recent Doppler-shift lifetime studies have used CsI(Tl) scintillator and silicon PIN diode arrays for fusion evaporation exit channel and inelastic scattering selectivity, respectively (TIP). Finally, the first test of in-beam internal conversion electron spectroscopy took place in December (SPICE), extending current transition rate measurement capabilities. This presentation will provide an overview of these systems and discuss recent experimental results of the TIGRESS nuclear structure program.
Speaker: Philip J. Voss (Simon Fraser University)
Doppler shift lifetime measurements using the TIGRESS Integrated Plunger device 15m
Electromagnetic transition rate measurements serve as a fundamental probe of nuclear structure and provide a stringent test for theoretical models. Doppler shift lifetime measurements offer an opportunity to directly access information about electromagnetic transition rates and discriminate between model calculations. To take advantage of this opportunity, the TIGRESS Integrated Plunger device (TIP) has been constructed at Simon Fraser University. The current TIP infrastructure supports lifetime measurements via the Doppler Shift Attenuation Method (DSAM) with charged particle identification provided by a modular silicon PIN diode wall and 24-element CsI(Tl) scintillator wall. One advantage of Doppler shift lifetime measurements is that lifetimes can be extracted independent of the reaction mechanism. TIP has been coupled to the TIGRESS segmented germanium array at TRIUMF as part of the experimental program at the ISAC-II facility at TRIUMF. The initial studies using TIP employ fusion-evaporation reactions. Here, reaction channel selectivity can greatly enhance the sensitivity of the measurement. To enable channel selection, the TIP CsI(Tl) wall has been coupled to TIP for evaporated light charged-particle identification. Reaction channel selectivity has been demonstrated using the TIP infrastructure following the successful identification of the $^{28}$Mg two proton evaporation channel from the $^{18}$O$~+^{12}$C reaction at the $^{18}$O beam energies of 56 and 48 MeV. DSAM lineshapes for the 1.2(1)ps $2^{+}\rightarrow 0^{+}$ transition and 105(35)fs $4^{+}\rightarrow 2^{+}$ transition in $^{28}$Mg have been observed. Geant4-based analysis code for TIP and TIGRESS is being developed to extract lifetimes from these experimental spectra and aid in the optimization of future experiments using this setup. The device, experimental approach, analysis, and preliminary results will be presented and discussed.
Speaker: Mr Aaron Chester (Simon Fraser University Department of Chemistry)
First in-beam test of SPICE 15m
A new ancillary detector, SPICE (SPectrometer for Internal Conversion Electrons) has been constructed and tested for the first time at the ISAC-II facility of TRIUMF. SPICE is designed to be coupled with the TIGRESS HPGe array to enable simultaneous in-beam gamma-ray and conversion-electron spectroscopy in both stable and radioactive ion beam experiments. The TIGRESS+SPICE setup will combine with other downstream detectors/arrays to provide the possibility for a broad range of reaction mechanisms, such as Coulomb-excitation or fusion evaporation, to be used to populate states of interest. The main focus of the SPICE design is the reduction of background due to low-energy particles and beam scattering, a high detection efficiency for electrons and a large energy-acceptance range between ~100 and 3500$\,$keV. This is achieved using a magnetic lens formed of permanent NdFeB magnets positioned upstream of the target and surrounding a truncated-conical-shaped high-Z-material photon shield. The internal conversion electrons emitted from the target are guided around the photon shield and detected by a large-area annular lithium-drifted silicon detector which is segmented into 120 individual segments. Reactions induced by a stable 12C beam at 67$\,$MeV impinging on a 3$\,$mg/cm$^2$ $^{196}$Pt target was studied with SPICE to demonstrate its capacity of detecting internal-conversion electrons in coincidence with gamma rays in TIGRESS. The residual $^{12}$C particles were detected with a double-sided annular silicon detector positioned at forward angles. A selective recoil-electron-gamma-type triggering for enhancing the signal-to-noise ratio of measurements was made possible by integrating the SPICE detector signals into the TIGRESS data-acquisition system. In the future, SPICE will be a powerful tool to measure conversion coefficients and $E0$ transitions in atomic nuclei thus providing a useful probe to study shape coexistence and quantum state mixing. An overview of the main features of the design and results from the test beam-time of SPICE will be presented as well as a look at future opportunities.
Speaker: Dr Mohamad Moukaddam (TRIUMF)
Exploiting the 8π spectrometer to probe nuclear matter and drive innovative applications at SFU and TRIUMF 15m
The 8π spectrometer was funded in 1984 by Atomic Energy of Canada Ltd. (AECL) and Natural Sciences and Engineering Research Council of Canada (NSERC) and comprised of 20 High Purity Germanium (HPGe) detectors, their BGO Compton suppressors with phototubes, and a 72 element inner BGO ball. After its use at the TASCC facility in Chalk River, it was moved to the Lawerence Berkeley Laboratory and then to the ISAC-I facility at TRIUMF. In early 2014 it was relocated to the Nuclear Science Laboratories at the Department of Chemistry, Simon Fraser University where it will be used for fission studies in its original configuration as a high-multiplicity spectrometer. Spare 8π HpGe detectors and electronics will be available as needed for trap-assisted decay spectroscopy at TITAN at TRIUMF. In addition, the 8π will become the detection system for neutron-activation analysis of interest to basic and applied research following installation of a neutron generator at SFU. The current status of the 8π spectrometer and its application will be presented and discussed.
Speaker: Krzysztof Starosta (Simon Fraser University)
20Ne and 22Ne fragmentation on 12C at 11.7 MeV per nucleon at TRIUMF 15m
The multidetector HERACLES studies heavy-ion collisions at TRIUMF, with ion beams with an energy range between 8 to 15 MeV per nucleon [1,2]. Seventy-eight detectors are axially distributed around the beam axis in 6 rings allowing detection of multiple charged fragments from nuclear reactions. Experimental data was collected by HERACLES from a 20Ne and 22Ne beam at 11.7 MeV per nucleon on a carbon target. For analysis, we compare experimental data with a hybrid code. Antisymmetrized Molecular Dynamics (AMD) treats the dynamics of colliding systems and GEMINI for the statistical deexcitation of fragments [3,4]. [1] M. Marchetto, ISAC-II Operations and Future Plans, LINAC'08 (2008)
[2] J. Gauthier, et al., Nuclear Instruments and Methods in Physics Research A 715, 18-27 (2013) [3] A. Ono, et al., Prog. Part. Nucl. Phys. 53, 501 (2004) [4] R.J. Charity, et al., Prog. Part. Nucl. Phys. 483, 371 (1988)
Speaker: Mr Patrick St-Onge (Université Laval)
(T2-3) Energy Frontier: Supersymmetry - PPD-DTP / Frontière d'énergie: supersymétrie - PPD-DPT C-112
Convener: Anadi Canepa (TRIUMF (CA))
Search for Supersymmetry at ATLAS 30m
The search for Supersymmetry in LHC proton-proton collisions with the ATLAS detector will be summarized. In particular, recent searches for gluinos, squarks (including top and bottom squarks), weakly-produced superpartners, R-parity violating SUSY and long-lived signatures will be presented.
Speaker: Jean-Francois Arguin (Universite de Montreal (CA))
Supersymmetry after the LHC data 30m
I discuss the theoretical motivations for weak-scale supersymmetry, including the gauge hierarchy problem, grand unification, and WIMP dark matter, and their implications for superpartner masses. These are re-assessed against the leading constraints on supersymmetry from collider searches, the Higgs boson mass, and low-energy constraints on flavor and CP violation. I also summarize attempts to quantify naturalness in supersymmetry, and implications for future experiments.
Speaker: Prof. Mariana Frank (Concordia University)
ATLAS Run1 Constraints on the Electroweak Sector of SUSY 15m
We present searches targeting electroweak production of supersymmetric particles in proton-proton collisions at the Large Hadron Collider with the Run1 data collected by the ATLAS detector. We review the limits on the masses of these supersymmetric particles and their production cross-section in the context of simplified models and the phenomenological Minimal Supersymmetric Standard Model.
Speaker: Zoltan Gecse (University of British Columbia (CA))
Search for Chargino and Neutralino Production in Final States with Three Leptons and Missing Transverse Momentum with the ATLAS detector in 20.3 fb^{-1} of sqrt{s}= 8 TeV pp collisions 15m
The Standard Model (SM) of particle physics provides a theoretical framework to understand fundamental particle interactions. Despite its extraordinary success, the SM leaves a number of open questions: What is the nature of Dark Matter? Why is the SM Higgs boson so light? Supersymmetry (SUSY) is an extension of the SM of particle physics which predicts a super-partner for each of the SM particles which differs by one-half unit of spin. In R-parity conserving SUSY models, the lightest supersymmetric particle (LSP) is stable, neutral and weakly interacting, providing a promising candidate to explain Dark Matter. In addition, SUSY provides a solution to the Hierarchy problem of the SM and allows for the unification of forces at the GUT scale. This talk focuses on a search for the direct production of charginos and neutralinos in final states with three leptons and missing transverse momentum. No excess above SM predictions was observed. Limits are set in the context of simplified models and R-parity conserving phenomenological Minimal Supersymmetric Standard Models.
Speaker: Matthew Gignac (University of British Columbia (CA))
(T2-4) Gender and Arts in Physics Teaching - CEWIP-DPE / Genre et arts dans l'enseignement de la physique - CEFEP-DEP C-114
Convener: Li-Hong Xu (University of New Brunswick)
The high cost of science disengagement of Canadian Youth: Reimagining Physics Teacher Education for 21st Century 45m
Last year, Let's Talk Science released a report on the cost of high school students' dropping science, technology, engineering and mathematics (STEM) subjects. The disengagement of Canadian students with STEM has dire economic and political consequences for the country: less than 50% of our secondary students take advanced STEM courses and even fewer decide to pursue science-heavy degrees. Thus, it is not surprising that for the past decade, Canada has been also falling behind on the innovation index. This talk will attempt to reimagine physics teacher education for the 21st century that will help engage Canadian youth in meaningful physics learning. In order to succeed in this process, teacher education should be grounded in physics education research. Moreover, it will require a long-term collaboration between physics faculty members, teacher educators, university administrators, and school districts. An example of the beginning of such collaboration will be discussed in this talk.
Speaker: Dr Marina Milner-Bolotin (The University of British Columbia)
Report on a Conference for Undergraduate Women in Physics (CCUWiP) held at McGill University in January 2014 15m
McGill University hosted on 10-12 January 2014 a first Canadian-version of a Conference for Undergraduate Women in Physics (CCUWiP). This conference was modeled after the successful CUWiP conference series centrally organized by the American Physical Society. We will describe the goals of this kind of conference, organizational details, and report on the event held at McGill. Thoughts about the future of these kind of events in Canada will also be discussed.
Speaker: Prof. Brigitte Vachon (McGill University (CA))
Stellar Physics 15m
Speaker: Mrs Rumila Narraidoo Ramiah (Research in Public Health)
(T2-5) Biophotonics I - DAMOPC-DIAP / Biophotonique I - DPAMPC-DPIA C-206
Correlative SHG/TEM imaging of collagen fibrils 30m
Type I collagen is a major structural protein in mammals and shows highly structured macromolecular organizations specific to each tissue. This biopolymer is synthesized by cells as triple helices, which self-assemble outside the cells into fibrils (10-300 nm) that further form fibers, lamellae or other 3D networks. This assembly mechanism depends critically on the collagen concentration, as well as on the temperature, pH and ionic strength of the solution in vitro. Thorough characterization of collagen fibrillogenesis is crucial to understand the biological mechanisms of tissue formation and remodeling and to design new collagen-based biomaterials. In this work, we continuously monitored the formation of collagen fibrils using time-lapse *in situ* Second Harmonic Generation (SHG) microscopy. Fibrillogenesis was triggered by increasing the pH in a dilute solution of collagen I and the increase of the fibril density was quantified in the SHG image stacks acquired sequentially overnight. Our results showed reproducible dynamics of fibrillogenesis that could be changed by tuning the pH. In addition we investigated surface-mediated fibrillogenesis by adding silica nanoparticles to the solution. We used Two-Photon excited fluorescence microscopy to visualize the stained nanoparticles and quantify the self-assembly of collagen around these nanoparticles to study the influence of inorganic materials on collagen matrices structuration. This study shows that SHG microscopy is a valuable technique for in situ 3D imaging of fibrillar collagen with sub-micrometer resolution. However, this optical technique cannot resolve most of the fibrils, which impedes quantitative measurements of the fibril diameter. Moreover, SHG is a coherent multiphoton signal, which scales in a complex way with the total collagen density. Hence, we correlated SHG microscopy to TEM to determine the sensitivity of SHG microscopy and to calibrate SHG signals as a function of the fibril diameter. To that end, we synthetized isolated fibrils with various diameters and successfully imaged the same fibrils with both techniques, down to 30 nm. The SHG signal scaled as the fourth power of the fibril diameter, as expected from analytical and numerical calculations. These results represent a major step towards quantitative SHG imaging of nm-sized collagen fibrils.
Speaker: Dr Stéphane Bancelin (Laboratory for Optics and Biosciences)
Single mode fibre transmission apparatus, measuring light where it counts 15m
Measuring fine loss in transmission of single mode fiber when coupled with 405nm laser light requires a sensitive apparatus as closed loop feedback systems are not commercially available. A stable laser and detector system are described which measure changes in transmission to within 0.02% change per hour over a 17-hour period. This measurement apparatus has proved useful in both pre-screening fibre systems for manufacturing, but also for determining the root cause of failure in the fibre. The transmission loss may be monitored with the detector positioned directly at the fibre, or at the focus of a relay optic placed after the fibre. Alternatively, the beam at the focus of the relay optic may be profiled on a CCD camera over time. The various measurement techniques are presented, and their use in determining the root cause of failure in transmission of the fiber. Some of various causes of failure include solarization of the fibre, contamination of the endface of the fibre, laser–induced periodic surface structure (LIPSS). Directly measuring for these requires destructive tests using for example atomic force microscopy or electron microscopy, whereas our measurement apparatus potentially provides for an indirect non-destructive means of determining the root cause of failure.
Speaker: Mr Chris F. Dimas (Spectral Applied Research)
Near-Infrared Excited Nanoparticles: Towards a Multimodal Platform 30m
Near-infrared (NIR) excited nanomaterials are emerging as useful tools in diagnostic medicine and therapeutics. Excitation with NIR light mitigates some of the drawbacks associated with the use of UV as the excitation source. NIR light is silent to tissues thus minimizing autofluorescence, possesses greater tissue penetration capabilities and does not incur damage to the sample. In this regard there has been an ever-increasing interest in lanthanide (Ln3+)-doped upconverting nanoparticles. With upconverting nanoparticles, it is possible to obtain UV/visible/NIR emissions using a single NIR excitation source (typically 980 nm) via a process known as upconversion. This multiphoton excitation process differs from what occurs in conventional multiphoton excited materials where the absorption of photons is simultaneous. In the case of Ln3+-doped materials, the multitude of long-lived "real" electronic energy states of the Ln3+ ions (from the partially filled 4f shell) allow for sequential absorption of multiple NIR photons eliminating the need for complex and expensive optical excitation. Thus, upconverted luminescence can be observed using an inexpensive commercial continuous wave diode laser. Here, we present the synthesis and surface functionalization of Ln3+-doped upconverting nanoparticles and demonstrate how they can be used in biological applications due to their interesting optical properties. Furthermore, we will show how these upconverting nanoparticles can be used as building blocks towards developing a multifunctional nanoplatform for the potential diagnostics and therapeutics of diseases such as cancer.
Speaker: Prof. Fiorenzo Vetrone (INRS-EMT, Université du Québec)
Interferometric Second Harmonic Generation imaging of biological tissues 15m
Second harmonic generation (SHG) microscopy is used to image structures lacking a center of inversion (non-centrosymmetric). Some biological tissues, particularly those made of collagen, possess this property. Because SHG microscopy is a coherent technique, the structure of the studied sample influences greatly the generated signal strength. By varying the polarization of the fundamental beam, the different $\chi^{(2)}$ elements of the sample can be measured and related to this structure. Hence, general alignment and organization of a tissue can be evaluated. However, the phase of the signal is lost in the measurement. In interferometric SHG (I-SHG) imaging, second harmonic is generated a first time out of the microscope. This signal is then directed towards the imaging setup where it interferes with the second harmonic generated in the tissue. By varying the relative phase between the two second harmonic signals that are interfering, the relative phase of the $\chi^{(2)}$ in the tissue can be retrieved pixel by pixel. We have used this technique to image myosin filaments in muscles, tendon, fascia and cartilage. This technique can help to understand the structure of these tissues at the $100~\mathrm{\mu m}$ level and relate it to its function in the human body and its evolution relative to disease and aging.
Speaker: Charles-Andre Couture (INRS)
(T2-6) Biophysics/Soft Condensed Matter I: Polymers - DCMMP-DMBP / Biophysique et matière condensée molle 1: polymères - DPMCM-DPMB A-226
Convener: Anand Yethiraj (Memorial University)
Mechanisms Affecting Glassy Dynamics in Thin Polymer Films 30m
Numerous studies have documented changes in the glass transition temperature (Tg) with decreasing thickness for thin polymer films less than ~100 nm in thickness. However, understanding of the fundamental mechanisms causing this phenomenon are still unknown. We have demonstrated that two separate mechanisms can act simultaneously to propagate enhanced mobility from the free surface deeper into the interior of the film resulting in two distinct reduced Tgs within single high molecular weight (MW) free-standing polystyrene films [1]. These two transitions, which can be separated by up to 60 K, show qualitatively different behaviors. The lower transition is MW dependent and appears to be unique to high MW chains, while the upper transition is MW independent and appears to be common across multiple glass forming systems such as polymers, small molecules, and colloids. We believe this more universal mechanism induces a gradient in dynamics near the free surface that propagates in via a mechanism related to cooperative motion [2]. Physical aging studies on polymer films are also underway to elucidate the stability and glassy dynamics of these thin films. For thick films (220-1800 nm) in which there are no Tg reductions, we find that the physical aging rate depends strongly on stress caused by thermal expansion mismatch between film and support. This stress, applied to the films as they are quenched into the glassy state, can nearly double the physical aging rate when changing the frame material from polycarbonate to silicon [3]. How stress and mechanical deformation impart mobility to polymer glasses has been studied primarily for materials where the glassy state was formed stress free. In contrast, we investigate the stability of polymer glasses after stress is applied during the formation of the glassy state (vitrification). Using a unique jig, constructed to apply a known stress to free-standing films during the thermal quench, we find that stress values above a threshold result in less stable polymer glasses with faster physical aging rates [4]. [1] J.E. Pye, C.B. Roth, Phys. Rev. Lett. (2011), 107, 235701. [2] J.E. Pye, K.A. Rohald, E.A. Baker, C.B. Roth, Macromolecules (2010), 43, 8296-8303. [3] J.E. Pye, C.B. Roth, Macromolecules (2013), 46, 9455-9463. [4] L.A.G. Gray, C.B. Roth, Soft Matter (2014), DOI:10.1039/c3sm52113c.
Speaker: Prof. Connie Roth (Emory University)
Diblock copolymer bridges: the break-up dynamics and enhanced stability of structured liquids 15m
Liquid bridges form when a liquid is stretched between two boundaries, creating a freestanding fiber. The break-up of simple Newtonian liquid bridges has been studied both theoretically and experimentally for a wide variety of different initial conditions since Plateau and Rayleigh considered the instability of a liquid jet. Though the break-up of liquid bridges composed of linear polymer melts and polymer solutions have been well studied, very little focus has been placed on the dynamics of diblock copolymer bridges. When annealed above the glass transition temperature and below the order-disorder transition temperature (ODT), diblock copolymers can organize into well-defined structures determined by the weight fraction of each polymer block. Conversely, as the temperature is increased above the ODT, the diblock will disorder and have properties more similar to a linear polymer melt. In this work, we monitor the evolution of diblock copolymer bridges to study the effect that diblock order has on dynamics and stability.
Speaker: Robert Peters (McMaster University)
Phase Behaviour of Polyelectrolyte/Homopolymer Blends 15m
The phase behaviour of polyelectrolyte/homopolymer blends is studied using self-consistent field theory. The blends are composed of charged and neutral homopolymers plus counter ions dissociated from the polyelectrolytes. We explore the phase behaviour of the system as a function of blend composition, charge density and interaction parameter. Besides the usual macrophase separation behaviour, the SCFT predicts that under appropriate conditions the system undergoes microphase separation, forming various ordered phases similar to diblock copolymers. We found that the formation of ordered structures is the result of the balance between the interactions and the mixing entropy of the ions. In particular, the domain size of the ordered phases is determined by the competition between the polymer-polymer interaction and counter ion entropy, thus it is not limited by polymer size. Increase in the repulsive interaction between the chains results in an increase in the domain spacing.
Speaker: Mr Ashkan Dehghan (McMaster University)
**WITHDRAWN** Monte Carlo Field-Theoretic Simulations for Melts of Diblock Copolymer 30m
Monte Carlo field-theoretic simulations (MC-FTS) are performed on melts of symmetric diblock copolymer for polymerization indices extending down to experimentally relevant values. The simulations are performed with a fluctuating composition field and a pressure field that follows the saddle-point approximation. Our study focuses on the disordered-state structure function, S(k), and the order-disorder transition (ODT). Although short-wavelength fluctuations cause an ultraviolet (UV) divergence in three dimensions, this is readily compensated for with the use of an effective Flory-Huggins interaction parameter. The resulting S(k) matches the predictions of renormalized one-loop (ROL) calculations over the full range of parameters examined in our study, and agrees well with Fredrickson-Helfand (F-H) theory near the ODT. Consistent with the F-H theory, the ODT is discontinuous and the shift in the ODT follows the predicted scaling.
Speaker: Prof. Mark Matsen (University of Waterloo)
(T2-7) Superconducting Materials - DCMMP / Matériaux supraconducteurs - DPMCM C-204
Convener: Michel Gingras (University of Waterloo)
Local moments in iron-based superconductors 30m
Understanding magnetism in iron-based superconductors presents a difficult challenge facing researchers in this field. While a local spin model seems to describe a large subset of experimental data, these compounds are distinctly metallic and the itinerancy of electrons must be crucial for magnetism. Recent studies have suggested that both local and itinerant nature could be in play, since there are multiple orbitals involved in the electronic structure of iron pnictides and chalcogenides. This viewpoint is supported by our recent x-ray emission spectroscopy (XES) studies, in which local magnetic moments are found in all samples studied. The Fe Kbeta XES is a fast, local probe that is bulk-sensitive and couples directly to the d-electron moment. In our survey of various materials in their paramagnetic phases [1], we found local magnetic moments in all samples studied. The moment size shows very little dependence on temperature or carrier concentration, but varies significantly across different families. Specifically, all iron pnictide samples have local moments of about 1.5-2 Bohr magneton per Fe atom, while FeTe and K2Fe4Se5 families have much larger local moments. The extracted moment sizes agree well with energy and momentum integrated inelastic neutron scattering results. In addition, XES was used to study the spin-state transition in rare-earths doped CaFe2As2 [2]. When about 10-20% of Ca is replaced with Pr or Nd ions, this material goes through the so-called collapsed tetragonal transition below 70 K, in which the c-lattice constant shrinks by almost 10% [3]. The XES data show that the local magnetic moment is quenched in this collapsed tetragonal phase. Our experimental results illustrate the importance of multiorbital physics in describing magnetism of iron-based superconductors. [1] H. Gretarsson et al., Phys. Rev. B 84, 100509(R) (2011). [2] H. Gretarsson et al., Phys. Rev. Lett. 110, 047003 (2013). [3] S. R. Saha et al., Phys. Rev. B 85, 024525 (2012).
Speaker: Young-June Kim (U)
Sudden reversal in the pressure dependence of Tc in the iron-based superconductor CsFe2As2: A possible link between inelastic scattering and pairing symmetry 15m
We report a sudden reversal in the pressure dependence of Tc in the iron-based superconductor CsFe2As2, similar to that discovered recently in KFe2As2. As in KFe2As2, we observe no change in the Hall coefficient at T=0, again ruling out a Lifshitz transition across the critical pressure Pc. We interpret the Tc reversal in the two materials as a phase transition from one pairing state to another, tuned by pressure, and investigate what parameters control this transition. Comparing samples of different residual resistivity $\rho_0$, we find that a modest increase in impurity scattering does not shift Pc. From a study of X-ray diffraction on KFe2As2 under pressure, we report the pressure dependence of lattice constants and As-Fe-As bond angle. The pressure dependence of various lattice parameters suggest that Pc should be significantly higher in CsFe2As2 than in KFe2As2, but we find on the contrary that Pc is lower in CsFe2As2. Our resistivity measurements under pressure reveal an intimate connection between the magnitude of inelastic scattering processes that contribute to resitivity and the critical pressure Pc.
Speaker: Fazel Fallah Tafti (U)
Shedding new light on the phase diagram of cuprate superconductors 30m
In 1986, condensed-matter physics was profoundly shaken by the discovery of high-temperature superconductivity in materials known as cuprates. With a transition temperature *Tc* above liquid nitrogen temperature, these materials quickly proved to be promising for technological applications. However, the major motivation for the scientific community has been to understand the fundamental mechanisms of superconductivity in those materials, in order to eventually push *Tc* even higher, hopefully up to room temperature. The phase diagram of cuprates as a function of temperature, chemical doping, magnetic field and pressure is challenging, as many different phases (insulating, metallic, magnetic, superconducting, etc.) intertwine and give spectacular and unexpected results. Despite attempts by many eminent theorists, a fully successful theory has not yet emerged. Recently, some experimental discoveries have shed new light on the mysterious phase diagram of cuprates. In this talk, I will review these discoveries and propose a scenario that could elucidate the phase diagram.
Speaker: Dr Olivier Cyr-Choinière (Université de Sherbrooke)
(T2-8) Plasma Physics and Applications - DPP / Physique et applications des plasmas - DPP C-301
Femtosecond few-hundreds-of-keV electron pulses from direct laser acceleration in a low-density gas 30m
Subrelativistic electrons are a valuable tool for high-resolution atomic and molecular imaging. In particular, electron pulses with energies ranging from 50 to 300 keV have been successfully used in time-resolved ultrafast electron diffraction (UED) experiments to probe physical phenomena on a subpicosecond time scale. Laser-driven electron acceleration has been proposed as an alternative to the static accelerator technology currently in use. In principle, it has several advantages : (i) the short wavelength of the accelerating field may lead to electron bunches with duration of the order of 10 fs or less; (ii) there is an intrinsic synchronization between the electron probe and the laser pump; and (iii) using a gas medium, the electron source is self-regenerating and could be used for UED experiments at high repetition rates. Recently, using three-dimensional particle-in-cell simulations, we showed that 240-keV electron pulses with 1-fs initial duration and 5% energy spread could be produced by radially polarized laser pulses focused in a low-density hydrogen gas [Marceau, et al., Phys. Rev. Lett. 111, 224801 (2013)]. The latest results suggest that 100-500 keV energy with similar duration is within reach of the actual laser technology.
Speaker: Dr Charles Varin (Université d'Ottawa)
Dense Plasma Focus for Isotopes Activation 15m
Dense Plasma Focus for Isotopes Activation, C. Xiao, R.A. Behbahani, Sean Wolfe (Plasmionique Inc.), A. Hirose, University of Saskatchewan -- A dense plasma focus (DPF) device (DPF-UofS) has been designed and is being fabricated and assembled at the University of Saskatchewan for production of short-lived radioisotopes utilizing the energetic ion beam emitted from DPF. Since the short-lived isotopes must be produced in proximity of treatment or diagnostic facilities such as PET (Positron Emission Tomography), DPF is a promising cost-effective and more portable alternative to cyclotron facilities. DPF-UofS will be formed by discharging a capacitor bank (30 kV, 4.5 μF) through a pair of coaxial electrodes. The Lee Model has been used to optimize the design of DPF-UofS. A maximum ion beam fluence of about 10^15 ions per shot, beam energy of 20 J has been predicted. For the 12C(d,n)13N reactions, the estimated radioactivity of 13N (half lifetime is about 10 minutes) is about 1 kBq per shot. To achieve the desired radioactivity, high capacitor bank energy and high repetition rate is required. The research is supported by CCNI, NSERC and CRC.
Speaker: Prof. Chijin Xiao (University of Saskatchewan)
Measurements of the Temporal Evolution of Ionization States of Warm Dense Aluminum with Betatron Radiation Produced from Laser Wakefield Acceleration 15m
Ultrashort duration Betatron X-ray Radiation results from the acceleration of relativistic electrons inside high intensity laser wakefield cavities. The femtosecond pulse duration and the synchronization properties make Betatron Radiation an ideal probe for investigating the dynamic properties of laser produced warm dense matter. Study of the ionization state of material in the non-equilibrium warm dense regime is a significant challenge at present. However, time-dependant x-ray measurements of K-shell absorption lines allows the ionization states of warm dense matter to be measured. In this paper, we report the results of employing ultrashort Betatron Radiation as a spectroscopic probe to temporally resolve the ionization states of warm dense aluminum. A Kirkpatrick-Baez Microscope was used to focus the radiation around the 1.5 keV photon energy range onto a 50-nm free-standing aluminum foil that was heated by a synchronized 800 nm laser pump pulse. By dispersing the K-shell absorption spectra in this range using a flat Potassium Acid Phthalate (KAP) Bragg crystal spectrometer, we observed the ionization states of warm dense aluminum as a function of time and heating pulse fluence. The details of experimental setup and initial measurement results will be presented. *Work supported by Natural Sciences and Engineering Research Council (NSERC) of Canada
Speaker: Prof. Robert Fedosejevs (University of Alberta)
(T2-9) Instrumentation - DIMP / Instrumentation - DPIM C-205
Convener: Kirk Michaelian (Natural Resources Canada)
The André E. Lalonde AMS Laboratory – the new accelerator mass spectrometry facility at the University of Ottawa 15m
The University of Ottawa, Canada, has installed a multi-element, 3 MV tandem AMS system as the cornerstone of the André E. Lalonde Accelerator Mass Spectrometry Laboratory, located in their new Advanced Research Complex (ARC). Manufactured by High Voltage Engineering Europa BV, the Netherlands, it is equipped with a 200 sample ion source, a high resolution, 120° injection magnet (mass-energy product 12 MeV-AMU), a 90° high energy analysis magnet (mass-energy product 350 MeV-AMU), a 65°, 1.7m radius electric analyzer and a 2 channel gas ionization detector. It is designed to analyze isotopes ranging from tritium to the actinides and to include the use of fluoride target materials. A research injection line, consisting of selected components from the IsoTrace Laboratory, Toronto is being added and will contain an upgraded demonstration version of the Isobar Separator for Anions, manufactured in collaboration with Isobarex Corp., Bolton, Ontario, Canada. This instrument uses selective ion–gas reactions in a radio-frequency quadrupole cell to attenuate both atomic and molecular isobars. Four new preparation laboratories are located in the ARC building for radiocarbon, radio-halide, tritium and actinide samples. Radiocarbon labs at Université Laval, Québec and Université de Québec à Montréal and a cosmogenic radioisotope lab at Dalhousie University, Halifax, Nova Scotia will also provide samples. This presentation will focus on the details of the new AMS equipment.
Speaker: Prof. William E. Kieser (Physics, University of Ottawa)
DETERMINING 210Pb BY ACCELERATOR MASS SPECTROMETERY 15m
Beams of PbF3- ions were produced initially using the 834 ion source at IsoTrace with targets of PbF2. Since a large count rate of common Pb could interfere with measurement of the rare 210Pb isotope we examined alternative target preparation chemistry to produce 210PbF3- beams. Beams of 150 to 175 nA of 208PbF3- were measured in targets prepared by adding the Pb to HF(aq) and equal parts of CsF and AgF2 and dried in a clean Savillex container. Although, this ion beam produces the highest counts of 210Pb, the factors controlling the beam stability require further study. 210Pb was detected in the +3 charge state using a conventional gas ionization detector at the IsoTrace Facility. Interference from the sum peak of 70Zn and 140Ce was measured in some targets. An anion exchange column separation was developed to separate 210Pb from 70Zn and 140Ce. Using this technique the sum peak of 70Zn and 140Ce was almost completely eliminated. We tested two different approaches to quantify the 210Pb concentration: (1) Measuring the 210Pb:205Pb ratio after adding 7.2pg of 205Pb, and (2) Measuring the 210Pb:208Pb ratio after adding 100µg of 208Pb and using a calibration curve coupled with the measurement of the concentration of 208Pb by ICPMS. The measurement of 205Pb was difficult because of 205Tl interference and molecular interferences at mass 205. Using the second technique, initial measurements of 210Pb in the CLV1 standard reference material agreed with the certified value of 660mBq g-1. Further work, using the high resolution injection magnet at the A. E. Lalonde AMS Laboratory at the University of Ottawa will improve the precision of these measurements.
Speaker: Mr Adam Sookdeo (University of Ottawa)
The Measurement of Cs isotopes by Accelerator Mass Spectrometry 15m
During nuclear weapons testing several caesium isotopes were released into the environment. Caesium 137 has been used in many studies. However this isotope has a relatively short half-life (30a) and it has already undergone ~50 years of decay. Caesium 135, another fissile isotope, has a much longer half-life ( about 2Ma) and could be used to replace 137Cs and the ratio between the two isotopes of Cs could be used to identify the source of Cs and to calculate the age of the source material.
However Cs-135 can be very difficult to measure. It cannot be gamma counted, as it is a pure beta emitter and beta counting is an impractical approach due to low decay rate. This leaves mass spectrometry as a viable option. While analyses using TIMS and ICPMS have been established, an analytical technique for accelerator mass spectrometry (AMS) still requires development.
The development of an AMS technique for 135Cs requires the development of (1) a beam of Cs anions, (2) a method to separate 135Cs from 135Ba and other ions with the same mass to charge ratio and (3) production of standards and yield tracers to measure the efficiency of the analytical process.
We have used the IsoTrace AMS facility and: (1) Tested a number of different Cs compounds to identify methods to produce Cs beams, (2) Successfully separated 135Cs from 135Ba using an Isobar Separator for Anions (ISA). This reaction chamber selectively reacts 135Ba with oxygen while allowing 135Cs to pass into the accelerator and (3) Used 134Cs as an internal standard and yield tracer.
Currently, the limitations in the analysis of 135Cs are the beam current and cross contamination during sputtering. An array of different Cs molecules are being tested and optimized for greater and more stable beam currents.
Speaker: Mr Cole MacDonald (University of Ottawa)
The VERITAS Observatory Upgrade: Performance and Status 15m
The VERITAS experiment measures Cherenkov light from air showers to study gamma rays of energies between 50 GeV and 50 TeV. During the summer of 2012, the VERITAS Collaboration completed an upgrade of the four VERITAS telescopes. The upgrade began in 2009 with the relocation of one of the telescopes to create a more symmetrical array configuration which resulted in a substantial increase in sensitivity. In 2011, the Level 2 (pattern) telescope trigger was replaced with a high speed, FPGA-based trigger, resulting in improved trigger efficiency and better background reduction. In summer 2012, the telescopes' photomultiplier tubes (PMTs) were replaced with high quantum efficiency PMTs which increased the telescope photon detection efficiency by approximately 50%. Furthermore, since fall 2012, observations have been carried out with VERITAS under bright moonlight, thanks to a combination of reduced high voltage and UV bandpass filters, which result in 15% more observing time over the course of the year. These improvements, coupled with refinements in the calibration and data analysis, have continued to improve the sensitivity of to the VERITAS experiment since its first light in April 2007. In this presentation I will provide an overview of the upgrade as well as details of the bright moonlight observing modes.
Speaker: Mr Sean Griffin (McGill University)
Investigations of Background and Compton Suppression Shields for GRIFFIN 15m
GRIFFIN (Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei) will replace the 8pi spectrometer at the TRIUMF ISAC facility by the end of 2014 with an array of 16 large-volume hyper-pure germanium (HPGe) clover detectors and instrument them with a state-of-the-art digital data acquisition system. The facility will be used to investigate a variety of aspects in nuclear structure, nuclear astrophysics and fundamental symmetries using stopped radioactive beams from ISAC. The most exotic nuclei are generally produced with the lowest intensity so in order to perform spectroscopy with these beams the greatest possible sensitivity is required. In addition, in the decay of intense beams it is often the weakest decay branches which are of the greatest interest. It is well established that active Compton-suppression shields comprised of bismuth germanate (BGO) can be an effective tool to increase the peak-to-total ratio of gamma-ray spectra collected with HPGe detectors. These active shields will also suppress background radiations originating from the experimental hall, which will further improve spectral quality. A series of measurements have been performed at ISAC using a GRIFFIN HPGe clover to characterize the spectrum of background events. The detector was then coupled with a TIGRESS BGO Suppression shield to investigate the effectiveness of such active shielding on the final gamma-ray spectrum. These measurements support the funding application for instrumenting the entire GRIFFIN array with suppression shields. A detailed description of the investigations and results will be presented. This work is supported by the Natural Sciences and Engineering Research Council of Canada.
Speaker: Nikita Bernier (TRIUMF)
(T3-1) Atmospheric and Space Physics - DASP / Physique atmosphérique et de l'espace - DPAE C-205
Convener: Richard Marchand (University of Alberta)
Ionospheric electron number density volumetric reconstruction with ADS-B: a new method to image the ionosphere. 15m
The proposed launch of CanX-7, carrying a space-borne ADS-B receiver developed by the Royal Military College of Canada will create a unique opportunity to study the modification of the 1090 MHz radio waves following propagation through the ionosphere from the transmitting aircraft to the passive satellite receiver. Our previous work has successfully demonstrated that ADS-B data is feasible as input to reconstruct two dimensional electron density maps of the ionosphere using techniques from computerized tomography. The goal of this work is to extend the model and reconstruct three dimensional (3D) electron density distributions to evaluate the feasibility of CT reconstruction in 3D with temporal variation. The data used as input for reconstruction was modelled using ray-tracing techniques for aircraft distributions from actual worldwide ground-based ADS-B data to a satellite orbit simulated in Satellite Tool Kit, and repeated for multiple satellites forming an arbitrary constellation with global coverage. Ray-tracing determined the characteristics of individual waves, including the wave path and the state of polarization at the satellite receiver. The modelled Faraday rotation was determined and converted to total electron content along each ray-path. The resulting total electron content was used as input for computerized ionospheric tomography using the algebraic reconstruction technique. This study concentrated on meso-scale structures 100–1000 km in horizontal extent. The primary scientific interest of this work is to show the feasibility of a new method to image the ionosphere and obtain a better understanding of magneto-ionic wave propagation.
Speaker: Alex Cushley
Wake modes in a supersonic flow 15m
When an object moves at supersonic speed, it creates a wake in the downstream region in the medium in which it propagates. In addition to the wake, that is, a region of depleted density, the supersonic flow also excites waves or normal modes, both downstream and upstream of the object. These modes can correspond to "surface modes" and, when the medium is a plasma, "cavity modes" can also be excited in the wake region. Results from a theoretical and computational study of these modes, associated with the wake region of a satellite in low Earth orbit (LEO) are presented. The study makes use of a decomposition of plasma fluctuations near a spacecraft, using the method of empirical eigen functions. Both the spatial and temporal structures of the perturbations are analyzed. The effects of photoemission and of the angle between the local geomagnetic field and the direction of the plasma flow velocity are also considered.
Speaker: Prof. Richard Marchand (University of Alberta)
(T3-2) Panel Discussion: Gender Equality - CEWIP / Table ronde : égalité des genres - CEFEP C-114
Being Alert: Identifying and Resolving Discrimination in a Physicist's Workplace 1h 30m
Moderator: Janis McKenna, University of British Columbia Panellists: Gabriela Gonzalez, Louisiana State University Melanie Campbell, University of Waterloo; Anadi Canepa, TRIUMF; Marina Milner-Bolotin, University of British Columbia; Michael Steinitz, St. Francis Xavier University; Li-Hong Xu, University of New Brunswick
(T3-3) Cavity QED and Optomechanics - DAMOPC-DCMMP / ÉDQ en cavité et optomécanique - DPAMPC-DPMCM C-206
Convener: Alex Brown (University of Alberta)
Nanoscale cavity optomechanics for quantum optics and sensing: diamond, Si and more 30m
By confining light to sub-wavelength volumes, nanophotonic devices enhance light matter interactions and enable a wide range of fundamental and applied studies. Nanophotonic optomechanics experiments probe optical coupling between nanomechanical resonators and photons. Using nanophotonic devices such as microdisk and photonic crystal nanocavities, it is possible to routinely measure thermal motion of nanoscale mechanical resonances. By harnessing the strong photon-phonon interactions within these structures, it is possible to optically manipulate – e.g., heat or cool – nanomechanical resonances. This talk will focus on recent progress in developing nanophotonic optomechanical devices for sensing and quantum optics applications. We have developed a silicon split-beam photonic crystal nanocavity with record torque sensitivity, gallium phosphide microdisks which support phonon-photon cooperativity exceeding unity, and single crystal diamond nanomechanical resonantors whose thermal motion can drive self-oscillations in the presence of an optical field. This talk will discuss prospects for using these devices for sensing and quantum optics applications.
Speaker: Paul Barclay (University of Calgary)
Optical trapping of the anisotropic crystal nanoparticle 15m
For modeling optical trapping of an anisotropic nano-particle we first used the point matching method to compute the T-matrix coefficients based on the boundary condition for the normal componants of D-fields. In the anisotropic media, where the divergence of E-field is nonzero, the Maxwell wave equations was sloved in the Fourier space. Thus, the plan waves with angular spectrum amplitude distributions can be expanded into the orthogonal and complete set of the Vector Spherical Wave Functions. The E-field eigenvectors can be obtained by the characteristic equation. In the point-matching mthod however we do not need to solve the entire internal field in the anisotropic particle, but an expression of the unknown internal field at the boundaries. We computed the stress distribution on the interfaces of an anisotropic nanocylinder and the related total lateral torque, spin torque and total force in the optical tweezers in order to put in evidence for mecanism of the optical trap of the anisotropic particle. The trapping beam was modeled as the vector Gaussian beam with high order corrections. After solving the scattered field the radiation stress was computed through the Maxwell stress tensor for anisotropic media by Robinson. Our calculation showed that optical stress can be not normal to the interface of anisotropic media. Our calculation predicted that when the optical axes of the anisotropic nanocylinder are not aligned with the cylinder axis, the nanocylinder can be trapped inclined with respect to the beam axis at an equilibrium position. Preliminary experimental observations came to support this prediction. Abstract (100 words) T-matrix
Speaker: Prof. Yunlong Sheng (Université Laval)
**WITHDRAWN** Laser-Enhanced Micromechanical Sensors 30m
In the field of optomechanics we have learned to use the forces exerted by laser light to gain a new level of control over a wide variety of mechanical systems. These systems range in size from kilogram-scale mirrors in gravitational wave detectors to nanomechanical elements in cryogenic environments. In this talk I will discuss how a very modest source of laser light (i.e. a few microwatts) can profoundly affect the motion of a micromechanical "trampoline" resonator. We are able to laser cool its mechanical motion to a very low temperature, and we can generate a nonlinear optomechanical coupling that could be used for quantum nondemolition (QND) readout of the trampoline's phonon number state or as a strong optical trap. Our group is currently most excited about using such optomechanical effects to replace traditional elastic materials in mechanical force sensing elements. Since the behavior of light in a cavity is fundamentally different from that of atoms in a flexible material, such devices should circumvent the limitations of the best existing materials and achieve an unprecedented level of precision. In the ultimate limit, we hope to use light-assisted mechanical devices to sense quantum superpositions from a variety of qubit technologies and faithfully imprint this information upon photons traveling down a standard telecom fiber.
Speaker: Jack Sankey (McGill University)
Adiabatic transfer of light in a double cavity 15m
We consider the controlled transfer of light between the two sides of an optical cavity containing a moveable membrane in the middle. The transfer process is analogous to STIRAP in atomic/laser physics. The system also presents some fundamental issues in cavity-QED and optomechanics because of the time-dependent boundary conditions. In particular, we compare and contrast Maxwell dynamics (2nd order in time) with Schrodinger dynamics (1st order in time).
Speaker: Duncan O'Dell (M)
(T3-4) Novel Light and Particle Sources - DAMOPC-PPD / Nouvelles sources de lumière et de particules - DPAMPC-PPD C-301
Laser-driven particle beamlines, challenges and bottlenecks 30m
Laser –generated particles are more and more considered to become a competitor to particle beams generated by traditional accelerator facilities such as Linac or synchrotrons. In particular, the high accelerating gradient that can be reached with laser-acceleration mechanisms, almost 1000 times stronger than for conventional accelerators, makes them an attractive alternative. A stronger accelerating gradient would reduce potentially the size and hence the costs of big accelerator facilities (e.g the LHC accelerator ring at CERN-Geneva, where the electron storage ring is around 27 km long). Unfortunately, the quality of the laser-generated beam parameters is currently not sufficient for replacing traditional facilities based on radiofrequency technology. In this paper we present the key issues and bottlenecks that we have identified in order to make laser-generated beams competitive to traditional accelerators. Results have been obtained using different particle-tracking codes commonly in use in the conventional accelerator community and coupling laser-generated beams to conventional accelerator devices in order to generate a traditional beam line. The particle tracking codes allow studying the relevant parameters needed for an efficient capture, transport and control of those beams. This would then generate reliable and controllable particles sources based on higher power laser systems, such as foreseen e.g. by the Extreme Light Infrastructure (ELI).
Speaker: Patrizio Antici (INRS)
High-Flux Table-Top Ultrafast Water Window X-Ray Source Driven By Mid-IR Laser Pulses 15m
Until very recently, Free Electron Lasers (FEL) and synchrotrons offering femtosecond (10$^{-15}$s) slicing technology have been the only facilities able to generate femtosecond X-Ray pulses in the water window (280-530 eV) spectral range. Bringing ultrafast science to the soft-X-Ray offer a wide range of application like studying multielectron dynamics in gas phase atoms/molecules, spectroscopy and imaging of biostructures in solution and time-resolved L-edge absorption spectroscopy to study ultrafast dynamics in magnetic materials. However, these facilities are associated with a huge initial investment and offer only limited access to a broad user community. An alternative technology is therefore necessary to make those ultrafast water window X-Ray pulses widely available. To generate those pulses, we realized a totally different approach, based on a taple-top extreme frequency upconversion mechanism called High Harmonic Generation (HHG). To do so, we use a customised high-energy optical parametric amplifier (OPA), delivering up to 10mJ of few-cycles pulses centered around 1.8 μm. We focus these pulses into a home-build gas-cell containing few tens of bars of helium, coupled to a flat-field X-Ray spectrometer. Through this highly nonlinear laser-atom interaction (HHG), high-flux ultrafast X-ray pulse trains, spanning almost the entire water window spectral range are than generated [1]. Single laser shot measurement of carbon K-edge (280eV) will be presented. [1] Légaré et al. (Manuscript in preparation)
Speaker: Mr Samuel Beaulieu (INRS-EMT)
Extreme light in nanostructured targets: shaping fields and managing particle flows 30m
The more intense that laser pulses can be made, the more surprising and extreme are the interaction effects researchers are seeing -- effects that are sometimes hard to control. One way to guide or redirect the physics relationships is to manipulate the composition or shape of targets. Nickel nanowires present >95% optical absorption into an effective skin-depth that is very long, greater than 1 μm. Partly this is due to the strong optical anisotropy of these oriented nanostructures: a dielectric in the transverse direction and a conductor along the optical axis. Under intense irradiation, and especially at relativisitic optical intensities, this can lead to transition from dielectric to conductor, strong JxB effects, nonlinear acceleration of electrons and the generation of high harmonic radiation. One remarkable recent result is that we see energy densities as high as 2GJ/cm^2, otherwise only available in NIF-compressed cores, and opening new possibilities for radiation and particle generation from modest-size intense ultrafast lasers. I'll outline our new theoretical and experimental results for intensities from small-signal up to very clean relativistic pulses.
Speaker: Robin Marjoribanks (U)
Diode Pumped Yb:YAG Ceramic Laser Amplifier Modules for a TW Laser System 15m
New ceramic laser materials allow the development of scalable, high efficiency and high repetition rate direct diode pumped laser modules. We are developing a diode pumped multipass amplifier as part of a new terawatt laser system being developed at the University of Alberta. Currently measurements are being carried out of the gain and extracted energy from a Yb:YAG ceramic disk amplifier stage pumped by 3 to 6 kW of pulsed diode pump power. These measurements are being carried out both at room temperature and at cryogenic temperatures where the potential efficiency and gain of the amplifier stage is improved. The results are then compared to rate equation modeling of the pulse amplification in the amplifier stage as a function of temperature and input pulse fluence. In these calculations we have included both the effect of temperature on the cross-section values (linewidth narrowing) and also the reduced lower laser level population due to the temperature dependent Boltzmann factor. We are currently establishing the best parameters for an overall model of the amplifier stage which will allow us to predict and design the optimum pump conditions and operating temperature for a given amplifier stage. The limitations in operating conditions due to transverse ASE are also being considered in these designs. The experimental measurements and modeling calculations will be presented.
Speaker: Mr Muhammad Raj Masud (University of Alberta)
(T3-5) Biophysics/Soft Condensed Matter II: Soft Interfaces - DCMMP-DMBP / Biophysique et matière condensée molle II : Interfaces molles - DPMCM-DPMB A-226
Convener: John Dutcher (University of Guelph)
Bacteria on surfaces – engineering surface microstructures to control bacterial adhesion and biofilm growth 30m
Bacteria are highly effective at populating living or inanimate surfaces, which causes significant problems in the healthcare industry, such as nosocomial infections, and the infection of medical devices. There is much to learn on the roles of surface topology at nano and micro scales, wettability and local adhesion forces on bacterial attachment and growth. This talk will present recent results on materials engineered to prevent bacterial attachment, and surface microtopologies to control and direct biofilm growth. Herein we demonstrate the role for superhydrophobic non-wetting surfaces to control (short-term) cell attachment, and we have modelled bacterial cell attachment as particles acting under a balance of local surface tension forces [1]. Further, we have designed a novel class of ultra low-adhesion surfaces (known as SLIPS) that incorporate a micron-scale thick lubricant layer immobilized at a surface [2,3]. These surfaces are highly effective to prevent the wetting of a wide range of contacting liquids, hydrophobic and charged particles, and bacterial cell adhesion. Importantly, many such designs that work by such physical mechanisms can be effective for a broad range of cell types, and are not biologically-specific and susceptible to resistance. [1] Hatton BD & Aizenberg J Nano Letters (2012)12(9):4551-4557; [2] Wong TS, et al. Nature (2011) 477(7365):443-447; [3] Vogel N, Belisle R, Hatton BD, Wong TS, & Aizenberg J Nature Communications (2013) 4(2167).
Speaker: Benjamin Hatton (U Toronto)
Surface tension effects in soft composites 30m
Solid surface tension is typically ignored, but can be very important in soft solids. It acts to minimise surface area, and can significantly change how the solids behave. I will talk about its role in determining the mechanical properties of soft composites. We make soft composites by embedding small inclusions in soft gels - with the aim of understanding how the composite microstructure controls is mechanical properties. Classical theory for composite behaviour works when the inclusions are sufficiently large, but below a critical lengthscale, it breaks down: surprisingly, making small holes in a soft material can actually stiffen, rather than soften the material. I will demonstrate how these strange effects are caused by solid surface tension.
Speaker: Dr Robert Style (Yale University)
(T3-6) Control of dynamical properties- DCMMP / Contrôle de propriétés dynamiques - DPMCM C-204
Convener: Kimberley Hall (Dalhousie University)
Electrical Detection of Dynamically Generated DC and AC Spin Currents 30m
Developing new methods for generating and detecting spin currents has been the central task of spintronics. In the pioneering work of Johnson and Silsbee, the generation and detection of spin-polarized currents were both achieved through the use of ferromagnetic metals (FM). Recent breakthroughs reveal ferromagnetic insulators (FI) to be promising spin current sources, in which spin currents can be generated without the presence of any charge current. So far, electrical detection of the spin current generated in FI was achieved by utilizing the spin-orbit coupling in heavy normal metal (NM) platinum (Pt). Given the fact that FM are broadly used as spin detectors in both semiconductor and metallic spintronics devices, it is of particular interest to develop new methods for detecting spin currents generated from an insulator using FM electrodes, which will make insulator spintronics devices compatible with both semiconductor and metallic spintronics devices. In this talk, we report dual spin pumping in magnetic bilayers made of a ferromagnetic insulator yttrium iron garnet (YIG) and a ferromagnetic metal Permalloy (Py). At the YIG ferromagnetic resonance (FMR), we detect a charge voltage in Py caused by YIG spin pumping. At the Py FMR, we measure the charge voltage generated by Py spin rectification. A striking simultaneous enhancement of both voltages is found at the equal resonance condition of both FMRs, which we attribute to dynamic coupling of the dual spin pumping. Our results demonstrate that Py enables electrical detection of both dc and ac spin currents in the spin pumping from YIG, which reveals a new path for developing insulator spintronics.
Speaker: Prof. Can-Ming Hu (University of Manitoba)
Ultrafast relaxation of exciton-polaritons in organic microcavities 15m
Exciton-polaritons are half-light, half-matter quasi-particles formed by excitons strongly coupled to the confined electromagnetic field of a microcavity. Their very low effective mass ($< 10^{-4} m_e$) and their bosonic character allows a phase transition to a Bose-Einstein Condensate (BEC) at relatively high temperature. Quantum effects such as spontaneous macroscopic coherence and superfluidity can then be observed. The proprieties of a BEC in inorganic quantum-well microcavities are well understood, but this effect in organic materials has not been clearly demonstrated. However, the large oscillator strength and the high exciton binding energy in such materials should allow formation of polariton condensates at higher temperature than achieved in inorganic microcavities and even to reach room temperature. In this presentation, I will describe our recent experimental efforts to reveal dynamics of polariton-polariton coupling in organic-semiconductor microcavities, which leads to the formation of quantum condensates. We employ two-dimensional electronic coherence spectroscopy (2D-ECS), an ultrashort technique belonging to the family of 2D Fourier spectroscopy. This technique uses a sequence of four ultrafast pulses with controlled spectral phase and delay to excite coherently a material system. Each pulse modifies the quantum states of the system in a known way. The signal emitted after the pulse sequence permit to build a correlation map revealing the nature of the coupling between different energy level. In our microcavities, it allows to probe polariton-polariton interactions along the dispersion curve, which ultimately leads to the formation of a BEC.
Speaker: Pascal Grégoire (Université de Montréal)
Phase transition of the escape rate in dimer model 15m
We study the phase transition of the escape rate of exchange-coupled dimer of single-molecule magnets which are coupled either ferromagnetically or antiferromagnetically in a staggered magnetic field and an easy $z$-axis anisotropy. The Hamiltonian for this system has been used to study dimeric molecular nanomagnet [Mn$_4$]$_2$ which is comprised of two single molecule magnets coupled antiferromagnetically. We generalize the method of mapping a single-molecule magnetic spin problem onto a quantum-mechanical particle to dimeric molecular nanomagnets. The problem is mapped to a single particle quantum-mechanical Hamiltonian in terms of the relative coordinate and a coordinate dependent reduced mass. It is shown that the presence of the external staggered magnetic field creates a phase boundary separating the first- from the second-order transition. With the set of parameters used by R. Tiron, $\textit{et al}$ , \prl {\bf 91}, 227203 (2003), and S. Hill, $\textit{et al}$ science {\bf 302}, 1015 (2003) to fit experimental data for [Mn$_{4}$]$_2$ dimer we find that the critical temperature at the phase boundary is $T^{(c)}_0 =0.29K$. Therefore, thermally activated transitions should occur for temperatures greater than $T^{(c)}_0$.
Speaker: Mr Solomon Akaraka Owerre (University of Montreal)
The Enhancement of the Figure of Merit for Thermoelectric Materials 15m
There is substantial interest in enhancing the Figure of Merit of thermoelectric materials in their applications to diverse fields such as energy and environmental studies [1,2]. The relationship between thermal and electrical conductivities is often described by the empirical Wiedemann-Franz law. Improvisations beyond this law have been found to be necessary to extend its scope to broader regimes. In the present work, we examine the roots of the extremization equations in thermoelectrics that result from optimization of the figure of merit using the polylogarithm functions of a complex variable [3]. Specifically, we study the roots of the Polylogarithms Lir(z)=0 for arbitrary index r, which can be both real or complex. The solutions can be exploited to improve the Figure of Merit of thermoelectric materials, and also to propose a modification of the Wiedemann-Franz law based on our findings. The use of the polylogarithm functions for maximizing the Figure of Merit will provide a valuable approach that complements numerical solutions in the literature. [1] Thermoelectric and thermomagnetic methods of energy conversion. Professor A.G. Samoylovich course of lectures - Chemivtsi: Ruta, 228 (2006). [2] A.A. Snarskii, M.I. Zheinirovskii, and I.V. Bezsudnov http://arxiv.org/ftp/arxiv/papers/1109/1109.1585.pdf [3] Muralikrishna Molli, K. Venkataramaniah, and S.R. Valluri, Can. J. Phys. 89: 1171-1178 (2011).
Speaker: Prof. Sree Ram Valluri (University of Western Ontario)
(T3-7) Cosmology - DTP / Cosmologie - DPT C-309
Convener: Arundhati Dasgupta (University of Lethbridge)
Early Universe Cosmology 30m
What did the Universe look like near the time of the Big Bang? What is the origin of structure in our Universe? Was there a time before the Big Bang? Precision cosmological measurements, such as those performed by the Planck satellite, have allowed us to confront some possible answers to these questions with data. In this talk, I will describe some of the current theories of the early universe, and how these ideas are being tested.
Speaker: Matthew Johnson (Y)
Clusters for Cosmology 30m
Over the past 30 years, cosmologists have made dramatic advances in establishing the fundamental parameters that govern the large-scale evolution of cosmic space-time. This progress is largely the result of experiments designed to measure the properties of the cosmic microwave background (CMB) to exquisite precision. CMB measurements, however, provide information about the state of the Universe when it was ~370,000 years old. The growth of cosmic structure - such as "clusters of galaxies", the most massive of the gravitationally bound objects in the universe - provides an alternate probe of the universe, albeit at the more recent epoch. According to the minimal standard model, the two sets of measurements ought to be give consistent results. However, recently released results from the Planck mission indicate that the two are in tension. Several resolutions have been proposed, of which the most exciting is that these results indicate the need for new physics. Another possibility is systematics in the "clusters for cosmology" program. Here I will provide a non-specialist overview of what this program entails, and provide recent results from the Canadian Clusters Comparison Project (CCCP).
Speaker: Arif Babul
Cosmological Perturbations in Antigravity 15m
We compute the evolution of cosmological perturbations in a recently proposed Weyl-symmetric theory of two scalar fields with oppositely-signed kinetic terms and conformal couplings (in lieu of minimal coupling) to Einstein gravity. At the background level, the theory admits novel geodesically-complete cyclic cosmological solutions characterized by a brief period of repulsive gravity, or "antigravity," during each successive transition from a Big Crunch to a Big Bang. We show that despite the wrong-signed kinetic term in the full action, these solutions are well-behaved (i.e. ghost-free) at the perturbative level.
Speaker: Mr Marius Oltean (McGill University)
The Echo of the Early Universe 15m
By applying quantum informational and optical tools to quantum gravity theories in the very early universe, we show that the fluctuations of quantum fields as seen by late comoving observers are significantly influenced by the history of the early universe, transmitting information about the nature of the universe in timescales when quantum gravitational effects where non-negligible. This might be observable even nowadays thus used to build falsifiability tests of quantum gravity theories.
Speaker: Dr Eduardo Martin-Martinez (Institute for Quantum Computing and Perimeter Institute for Theoretical Physics)
(T3-8) Searches for Higgs in the Standard Model and beyond - PPD / Recherches pour Higgs dans le modèle standard et au-delà - PPD C-112
Convener: Dr Wojtek Fedorko (University of British Columbia)
Search for resonant $VH$ production with a $W$ or $Z$ boson decaying leptonically 15m
The search for $pp \rightarrow Vjj$ with a dijet resonance is motivated by a number of theories going beyond the Standard Model. The Higgs boson discovery by ATLAS and CMS imposes strong constraints on theories beyond the Standard Model. Minimal Walking Technicolor (MWT) proposes a dynamical approach to explain the electroweak symmetry breaking and is of interest as it includes a light composite Higgs-like scalar particle. It also predicts resonant $VH$ associated production coming from a mixture of vector and axial-vector mesons. This presentation will focus on the latest results in the search for such resonances in the 3 leptonic channels of $Vbb$ using the data collected from 8 TeV $pp$ collisions with the ATLAS detector with interpretation in terms of the MWT model.
Speaker: Frederick Dallaire (Universite de Montreal (CA))
Search for Associated Higgs Boson Production in the WH→ WWW(∗)→ lνlνqq Decay Mode Using 20.3 fb−1of Data Collected with the ATLAS Detector at √s = 8 TeV 15m
A search for the Higgs boson in the associated production mode WH → WWW(∗) → lνlνqq (l = e, μ) performed combining the 20.3 fb−1 of proton-proton collision data at a centre-of-mass energy of 8 TeV collected in 2012 and the 4.7 fb-1 of proton-proton collision data at a center-of-mass energy of 7 TeV collected in 2011 with the ATLAS detector. Assuming a Higgs mass of 125 GeV, a 95% CL limit of approximately 6.8 times the Standard Model is set. Major backgrounds and techniques for suppressing them will be discussed. Backgrounds which are not well modelled by Monte Carlo simulation are estimated with data driven methods, or have additional systematic uncertainties estimated with data driven methods assigned to them.
Speaker: Joseph Peter Kinghorn-Taenzer (University of Toronto (CA))
Cut-based analysis of the Z-associated Higgs-strahlung process Z(H->WW) using data from the ATLAS experiment and Monte Carlo simulations 15m
In the Standard Model of particle physics, there exist several modes by which a Higgs boson may be produced, and several modes by which it may decay. In order to accurately characterize it via measurement of its couplings to other particles, the statistically significant combinations of these production and decay modes must be studied. An analysis of one such combination is presented here, using data from the ATLAS experiment at CERN and Monte Carlo simulated (MC) samples: the Z-associated Higgs-strahlung process, $f\bar{f}\rightarrow Z(H\rightarrow WW^*)$. A set of selection criteria (cuts) for events is optimized to maximize signal-to-background; this optimization is done against MC samples of the relevant background and signal processes in order to avoid bias from the data. Additionally, subsets of the data and MC samples orthogonal to the signal region are studied to determine *scale factors*, which are applied to the normalization of the MC samples to correct for mismodelling. Both the cuts and scale factors are frozen before unblinding the data. Finally, the results obtained from applying the cuts to the data and MC samples are used to set a limit on the ZH production cross-section (statistics are not sufficient for a direct calculation of the value), which will eventually be used in a fit to determine the aforementioned coupling strengths.
Speaker: Aaron Arthur Liblong (University of Toronto (CA))
(T3-9) Neutrinos: Underground and Future - DTP -PPD-DNP / Neutrinos: sous terre et avenir - DPT-PPD-DPN FA-054
Convener: Andrei Semenov
Neutrino Theory Impacts 30m
Whereas great strides have been made in the experimental measurements of neutrino properties, a definitive theory of neutrinos is yet to emerge. I will discuss some selected theoretical ideas, including the possible link between neutrinos and other phenomena such as dark matter and astrophysics.
Speaker: Prof. Ernest Ma (University of California, Riverside)
Calibrating the SNO+ Detector 15m
SNO+ is a scintillator experiment at SNOLAB searching for neutrino-less double-beta decay in Tellurium-130, as well as detecting low energy solar neutrinos, and reactor- and geo-antineutrinos. Good understanding of our energy response is crucial, especially in making the double beta decay measurement. SNO+ will deploy radioactive calibration sources to study the detector's response to different particle types, position and energy reconstruction, and energy resolution at the double-beta endpoint. I will focus on the development and simulation of a new AmBe source and upgrading the existing SNO calibration hardware to a closed, airtight system, both of which are needed to for compatibility with our new LAB-based scintillator.
Speaker: Erica Caden (L)
Water Assay Using Hydrous Titanium Oxide Technique for the SNO+ Experiment 15m
SNO+ is a multipurpose neutrino physics detector, located 2 km deep underground at SNOLAB in Sudbury, Canada. The SNO+ Acrylic Vessel (AV) will be filled with 780 tons of liquid scintillator, Linear Alkyl Benzene (LAB). The AV is surrounded by about 7000 tonnes of ultrapure light water, which shields the detector from naturally occurring radioactivity in the surrounding rock, PMTs etc. To achieve the radiopurity requirements for physics data, the water must be very clean on the level of 238-U: 2.06 X 10^-13 gU/g water and 232Th: 5.20 X 10^-14 gTh/g water. The existing water assay technique, Hydrous Titanium Oxide (HTiO), is used for assaying the radioactive backgrounds in the water from different regions of the SNO+ detector. Several steps are involved: deposition, extraction, elution, and secondary concentration. The amount of Ra in the sample is then determined by Bi-Po coincidence counting and the amount of 232Th and 238U present in the water is determined as well. All steps involved in the HTiO assay technique are presented as well as a sample analysis.
Speaker: Ms Dimpal Chauhan (Queen's University)
Heads/Chairs Business Meeting / Réunion des directeurs de départements L-507
Professional Development: Professional Affairs - Affaires professionnelles W-130
Elements of Professional Practice for Physicists 30m
Elements of Professional Practice for Physicists Prepared by: M.K. O'Neill , M.Sc. (Physics), P.Eng, P.Phys and Dr. Stephen Pistorius M.Sc. (Med) Ph.D. (Physics), P.Phys., FCOMP for the CAP Professional Affairs Committee The Canadian Association of Physicists has established a professional designation: Professional Physicist (P.Phys). Although qualifying criteria are in place for P.Phys applications, other aspects of professional practice have not been fully developed. The purpose of this talk and workshop is to explore elements of professional practice through a review of practices found in other professions, as well as legal obligations, such as expanded duty of care, which are inherent to professional practice . We will cover topics such as the general nature of professional practice, the common elements of professional practice, and the application of these to P.Phys professional practice.
Speaker: Mr Michael O'Neill (CAP - PAC)
CEWIP Annual Meeting & Reception / Assemblée annuelle CEFEP et réception C-114
Progressive Dinner at Science North Museum Science North
Science North
includes open access
CNILC Breakfast Meeting / Réunion du comité de liaison national canadien de l'UIPPA C-201
(W1-1) Experimental Advances and Acccelerators - DNP-PPD-DIMP / Progrès expérimentaux et accélérateurs - DPN-PPD-DPIM C-304
Convener: René Roy (Université Laval)
The International Linear Collider - a precision probe for physics at the TeV scale 30m
The Standard Model is the most comprehensive present day precision theory of particle interactions. Nonetheless, many key questions in subatomic physics and cosmology remain unanswered. The recent discovery of a Higgs-like particle at the Large Hadron Collider (LHC) has raised new questions. The International electron-positron Linear Collider (ILC) is being planned as the next high-energy world facility for particle physics. Precision experiments at the ILC will be essential in unambiguously interpreting LHC physics discoveries. ILC physics demands much better performance than previous or current collider detectors have achieved. The project status, in the context of Japan as a potential ILC host, will be summarized. The collider and detector challenges will be described with focus on specific tracking, calorimetry and accelerator ILC R&D activities in Canada.
Speaker: Alain Bellerive (Carleton University (CA))
The Advanced Rare IsotopE Laboratory (ARIEL) at TRIUMF 30m
TRIUMF, Canada's national laboratory for Particle and Nuclear Physics, has made substantial progress towards the construction of the Advanced Rare IsotopE Laboratory (ARIEL), which is its flagship project towards advancing isotopes for science and medicine. ARIEL will ultimately triple the current rare isotope beam capability, facilitating many more experiments in material science, nuclear physics, nuclear astrophysics, and fundamental symmetry tests as well as enable development of new isotopes for nuclear medicine. Rare isotope beams from the photo-production with the new electron linear accelerator (e-linac) and from the proton induced spallation and fission employing a new proton beam line from TRIUMF's 500 MeV cyclotron will make use of the existing world-class experiments of TRIUMF's ISAC facility. This talk will give an overview on the progress of the ARIEL project and describe the plans for completing the project in five phases, each enabling new science capabilities.
Development and Licensing of SFU Neutron Generator Facility 15m
Subcritical Intense Multiplier Of Neutrons (SIMON) is a proposed neutron generator facility in the Department of Chemistry at Simon Fraser University. The facility aims to support a research program including production and separation of radioisotopes for medical applications, as well as studies of nuclear structure, neutron induced fission, neutron activation for non-destructive elemental analysis of materials, and to study the feasibility of subcritical accelerator-driven multiplication of neutrons. As part of the SIMON facility licensing process with the Canadian Nuclear Safety Commission, dose rate predictions were computed via Monte-Carlo methods using the GEANT4 (GEometry ANd Tracking 4) simulation framework. Annual dose rate contributions to personnel-occupied work areas surrounding the neutron generator vault are predicted to be less than half of the Health Canada limit of 1 mSv/yr for members of the public. Recent and upcoming developments, including receipt of the license to construct the facility, ongoing construction of the facility, and independent verification of the dose rate predictions, will be discussed.
Speaker: Mr Jonathan Williams (Simon Fraser University)
Study of a Large Prototype TPC using Micro-Pattern Gas Detector Readouts 15m
During the last decade, detector R&D for the future International Linear Collider (ILC) has been performed by the community. The International Large Detector (ILD) is one detector concept at the ILC where calorimetry and tracking systems are combined. The tracking system consists of a Si vertex detector and forward tracking disks, as well as a large volume Time Projection Chamber (TPC). Within the framework of the LCTPC collaboration, a Large Prototype (LP) TPC has been built as a demonstrator. Its endplate is able to contain up to seven identical modules of Micro-Pattern Gas Detectors (MPGD). Recently, the LP has been equipped with resistive anode Micromegas (MM). A team from Canada participates in the deployment and study of the MM technology with a 5 GeV electron beam in a 1 Tesla magnet at DESY. After introducing the LP, the current status, recent results (drift velocity, field distortions and spatial resolution measurements) as well as future plans of the MM readout will be presented.
Speaker: Mr Peter Hayman (Carleton University)
(W1-2) 100 Years of X-ray Diffraction - DHP-DCMMP / 100 ans de diffraction des rayons X - DHP-DPMCM C-309
Convener: Sjoerd Roorda (Université de Montréal)
History of X-ray Diffraction in Canada 45m
This talk will discuss the history of x-ray diffraction, with an emphasis on a Canadian perspective. It will discuss important milestones of x-ray diffraction, the history of x-ray sources and discuss diffraction research with an emphasis on Canadian Research.
Speaker: Mark Sutton
Biomedical Imaging Applications of X-Ray Diffraction 45m
The use of x-ray diffraction optics for biomedical imaging has provided a very fruitful area of instrumentation development, especially at synchrotron sources. Such optics have driven a number of biomedical imaging applications such as K-edge subtraction imaging (a form of element specific imaging), analyzer based imaging or diffraction enhanced imaging, Talbot or interferometry based imaging and in-line phase contrast imaging. The biomedical beamline at the Canadian Light Source provides an ideal environment to develop and test new optical systems with the motivation to provide new tools for the biomedical community. Our group is actively involved in all aspects of optical system development and application. Recently, we have developed a new "spectral" approach to K-edge imaging that may soon lead to rapid 3D imaging of a contrast element including the potential for speciation imaging. We have developed x-ray optics that angularly disperse a wide range of continuous imaging energies for multi-elemental analysis (~12keV range centered at 35keV) and imaging at several specific energies simultaneously (multiple energy imaging). Most recently, we have explored ways to very efficiently expand our imaging beam vertically to better match the size of the subjects. An interesting aspect of the optic is that provided a vertical beam size that would have been possible with a beamline 12 times longer than the actual length of 25m. This allows us to much better utilize the intensity of the synchrotron beam and will lead to a unique capability for dynamic imaging. Examples of all of these developments and their application will be presented along with a future perspective will be given.
Speaker: Dean Chapman (University of Saskatchewan)
(W1-3) Condensed Matter Theory - DTP-DCMMP / Théorie de la matière condensée -DPT-DPMCM C-204
Convener: Louis Marchildon (Universite du Quebec a Trois-Rivieres)
Correlated electron physics in quantum materials 30m
In this talk, I will review recent developments of strongly correlated electron systems in transition metal materials. In particular, transition metal oxides exhibit novel quantum phases including unconventional superconductivity, electronic nematic phases, topological Mott insulators, and quantum spin liquids. This rich variety of phenomena stems from the interplay among charge, spin, orbital, and lattice degrees of freedom. After a general review, I will focus on Iridium-based oxides which display exotic magnetic phases and quantum spin liquids. Combined effects of spin-orbit coupling and electronic correlation will be also presented.
Speaker: Jeffrey Rau (University of Toronto)
The Haldane-like spin chain in the large anisotropy limit 30m
We consider the one dimensional spin chain similar to the one studied by Haldane, however in the opposite limit, of very large anisotropy and small nearest neighbour, anti-ferromagnetic exchange coupling between the spins. The zero order theory has a ground state that is 2^N degenerate, corresponding to each spin in its highest or lowest weight state. For a periodic chain with an even number of sites we show that the ground state is a superposition of the two possible Néel states. We explicitly find the instanton that mediates the tunnelling, within the spin coherent state formalism. With an odd number of spins, the Néel state must necessarily contain a defect. The position of the defect is arbitrary and the set of ground states reorganize into a band, with the ground state given by the linear superposition of the localized defect states. We show that at order 2s in perturbation theory, the localized states mix. In both cases, the ground state does not admit long range order, confirming the result that symmetry break down does not occur in one dimensional systems.
Speaker: Prof. Manu Paranjape (Université de Montréal)
Perturbative non-Fermi liquids from dimensional regularization 15m
A dimensional regularization scheme for quantum field theories with Fermi surface is proposed to study scaling behaviour of non-Fermi liquid states in a controlled approximation. Starting from a Fermi surface in two space dimensions, the co-dimension of Fermi surface is extended to a general value while the dimension of Fermi surface is fixed. When Fermi surface is coupled with a critical boson centred at zero momentum, the interaction becomes marginal at a critical space dimension $d_c=5/2$. A deviation from the critical dimension is used as a small parameter for a systematic expansion. This method is applied to the theory where two patches of Fermi surface are coupled with a critical boson, and it is shown that the Ising-nematic critical point is described by a stable non-Fermi liquid state slightly below the critical dimension. Critical exponents are computed up to the two-loop order.
Speaker: Denis Dalidovich (P)
Thermodynamic Induction 15m
A nonequilibrium thermodynamic theory demonstrating an induction effect of a statistical nature will be presented. We have shown that this thermodynamic induction can arise in a class of systems that have variable kinetic coefficients (VKC). In particular if a kinetic coefficient associated with a given thermodynamic variable depends on another, faster, thermodynamic variable then we have derived an expression that can predict the extent of the induction. The amount of induction is shown to be proportional to the square of the generalized driving force. This result constitutes an extension of the Onsager symmetry relations to the nonlinear realm. We note an important sign difference. While the entire system approaches thermodynamic equilibrium, some variables may be induced to leave thermodynamic equilibrium. Some subsystems may move to lower entropy configurations, for sustained periods of time, without violating the second law of thermodynamics. Also, induction allows the entire system to approach equilibrium faster than expected. Thus we present a nonequilibrium version of Le Chatelier's principle. We have also developed a variational approach, based on optimizing entropy production, in a certain sense. On the question of resolving whether entropy production is minimized or maximized, we conclude neither, but we produce a function that is maximized. The maximization occurs while the fast variables are quasistationary. Thus, the stationary states of Prigogine, introduced in the context of the minimum entropy production principle, are still very useful. Finally, we will discuss possible schemes directed towards discovering experimental evidence for thermodynamic induction, including manipulation of individual atoms using a scanning tunnelling microscope.
Speaker: Steve Patitsas (U)
(W1-4) Fields and Strings - DTP / Champs et cordes - DPT C-114
Quantum gravity on a quantum computer? 30m
Quantum information theoretic tools could be used to study the most basic physical phenomena. For example, measurements of quantum entanglement allow one, in principle, to detect curvature. I am proposing that curvature may be expressible entirely in terms of entanglement. This would open up the prospect that quantum gravity could be simulated on a quantum computer. Mathematical results that arise in these studies yield surprising answers to questions of the type famously described by Kac's as "Can one hear the shape of a drum?"
Speaker: Prof. Achim Kempf (University of Waterloo)
Unruh-Dewitt detectors and AdS Black Holes 15m
It is well-known that black holes emit Hawking radiation, which has a characteristic temperature; observers outside the black hole observe the emission of particles. We consider a conformally coupled scalar field around a black hole in an asymptotically AdS spacetime. By using a simple model of a particle detector, we can probe the spectral features of this radiation. We calculate the response of the detector with respect to its energy gap. Numerical simulations show that the radiation, while thermal, is not featureless; there are characteristic peaks at certain frequencies. We then provide evidence that these peaks are due to quasinormal resonances.
Speaker: Keith Ng (University of Waterloo)
Particle Detectors as Topological Probes 15m
The apparent triviality of the topology of our universe stands in stark contrast to the properties of general relativity, which admits all possible topologies. The topological censorship theorem resolves this conundrum insofar as it relegates all isolated topological structures (such as wormholes) inaccessible to observers by any classical experimental means. I will show here that an Unruh-DeWitt detector can indeed probe the global topology of a spacetime by making local measurements of a quantum field. Specifically, I will consider a massless scalar field on the BTZ spacetime — the 2+1 dimensional analog of a Schwarzschild spacetime — coupled in the canonical way to a particle detector. I will examine several trajectories of the detector, illustrating how the detector is sensitive to the topology that is partially hidden behind horizons. Implications for the topological censorship theorem will be discussed.
Speaker: Alexander Smith (U)
The Continuum Limit of the Unruh Effect in a Cavity 15m
Building on previous numerical non-perturbative studies of the Unruh effect on a harmonic-oscillator-detector in a cavity, we seek to explain the nuances involved in taking the continuum limit of an Unruh-DeWitt detector as the cavity becomes large. While we have previously replicated the linear dependence of temperature on acceleration, here we will discuss how in the continuum limit the slope of this dependence will converge to $1/2\pi$, with vanishing constant term. Our ability to directly examine the detector's thermality will guide us towards a resolution.
Tunneling and domain walls 15m
We consider a field theory model in 1+1 dimensions with a discrete internal symmetry. The model is such that the true vacuum respects this symmetry but it is broken in a pair of false vacua. Solitons interpolating between the false vacua necessarily pass through the true vacuum and are unstable. Adding a second scalar field, it is possible to stabilize the soliton against small fluctuations. Nonetheless, such a soliton will necessarily decay via quantum tunneling, just as the false vacuum itself is unstable. We analyse this phenomenon, and study whether the presence of solitons has a significant effect on the stability of a false vacuum.
Speaker: Richard MacKenzie (U)
(W1-5) Biophysics/Soft Condensed Matter III: Phase Behaviour and Kinetics - DCMMP-DMBP / Biophysique et matière condensée molle III: Comportement et cinétique de phase - DPMCM-DPMB A-226
Convener: Sheldon Opps (U)
Pressure-induced interdigitation in bicellar mixtures containing anionic lipid 30m
Phospholipid bilayer interdigitation can be induced by the application of hydrostatic pressure. Bilayers of anionic lipid are known to interdigitate at lower pressures than bilayers of corresponding lipids with zwitterionic headgroups. Dispersions of lipid mixtures with long and short chains, known as bicellar mixtures, can exist as small bilayered micelle disks at temperatures below the gel-to-liquid crystal transition temperature of the long chain component, magnetically orientable extended micelles at intermediate temperature, and lamellar phases at higher temperature. For mixtures of dimyristoyl phosphaticylcholine (DMPC) and dihexanoyl phosphatidylcholine (DHPC), interdigitation has been reported at pressures above 400 MPa [Jeworrek, Uelner, Winter, 2011, Soft Matter 7, 2709]. In the current work, dispersions DMPC-d54, the anionic phospholipid dimyristoyl phosphatidylglycerol (DMPG), and DHPC, with molar ratios 3:1:1, have been studied using variable-pressure 2H NMR at temperatures up to 60oC and pressures up to 140 MPa. The resulting pressure-temperature phase diagram displays a region of interdigitation that extends down 120 MPa at 56oC. However, by cooling this mixture from about 50oC at pressures above 83 MPa, it is also possible to induce metastable interdigitation that can persist to lower pressures and temperatures. This may reflect kinetic trapping of a non-equilibrium lateral distribution of the short-chain DHPC component. These observations provide new insights into how lipid assembly morphology is determined by the balance between component interactions in the bilayer interfacial and hydrophobic regions. Supported by NSERC.
Speaker: Michael Morrow (Memorial University of Newfoundland)
Study of chiral molecular diffusion in anisotropic liquids 15m
Very often the cholesteric liquid crystals are obtained by mixing a small quantity of chiral molecules in a nematic liquid crystal host. The homogeneous mixture is obtained by molecular diffusion, which takes place due to chaotic (thermal) motion of individual molecules. This process is temperature dependent. However, the breakdown of physical symmetry also affects dramatically the diffusion process. In the present work, we study this diffusion for different boundary conditions from orientational point of view. We compare the same diffusion process with the case of non-chiral molecules. Some theoretical estimations are made to try to model the experimentally observed phenomenon.
Speaker: Karen Allahverdyan (Laval University)
Competition Between Phase Separation and Crystallization in Attractive Colloids 30m
This presentation will focus on results from recent experiments on earth and on the International Space Station investigating the interplay between phase separation and crystallization in samples prepared in the three-phase region (gas-liquid-crystal) of the phase diagram of a colloid-polymer mixture. On earth, our samples first separate into a colloid-rich phase and a colloid-poor phase, with crystals forming in the colloid-rich phase. The denser phases sediment as expected. In microgravity, photographic images obtained in the BCAT-5 experiment reveal phase separation with crystal formation in the denser phase, where the phase separation continues normally until the dominant length scale is about 25% of the cell thickness, at which point both phase separation and crystal growth are arrested before macroscopic phase separation can occur. We propose that this arrest occurs because the surface tension is not sufficient to overcome the stiffness of the crystalline network that forms in the liquid phase. Supported by the Canadian Space Agency and NSERC.
Speaker: Barbara Frisken (S)
Inverse melting and phase behaviour of core-softened attractive disks 15m
We use several computer simulation techniques to study the phase behaviour of a simple, two dimensional model that was originally devised to understand the anomalous properties of liquid water and their connection to a hypothesized liquid-liquid critical point. The interaction potential of this one-component system comprises a repulsive shoulder and an attractive square well. In our phase diagram of the model we find that the system exhibits inverse melting, for which the system crystallizes upon isobaric heating, over a small range of pressure [1]. We find that the range of pressures over which inverse melting occurs can be enlarged by increasing the extent of the repulsive shoulder [2]. Although our study is in 2D, we find that the transition is first order and to a liquid, rather than to a hexatic or quasicrystal phase. The increase in the range of inverse melting results in a change in the topology of the phase diagram, leading to further interesting behaviour. [1] A. M. Almudallal, S. V. Buldyrev, and I. Saika-Voivod, J. Chem. Phys. 137, 034507 (2012). [2] A. M. Almudallal, S. V. Buldyrev, and I. Saika-Voivod, arXiv:1401.0679 (2014).
Speaker: Ahmad Almudallal (Memorial University of Newfoundland)
(W1-6) Cold Atoms and Molecules - DAMOPC-DCMMP / Atomes froids et molécules - DPAMPC-DPMCM FA-054+5+6
Convener: Frank Hegmann (U)
Spin transport in a unitary Fermi gas 30m
The thermodynamic properties of unitary Fermi gases are called universal, since they do not depend on the strength or physical origin of their interactions. For the same reason, one might expect dynamics to be universal. We report on the growth of interactions and the loss of magnetization in a gas initialized with full transverse magnetization. Such a gas has no interaction energy, since each atom is in the same superposition of magnetic eigenstates. However, in the presence of a magnetic field gradient, this is a non-equilibrium state, and relaxes to an unmagnetized, fully interacting state, at higher temperature. We present our measurements of these dynamics, and discuss implications for our understanding of the unitary Fermi gas.
Speaker: Prof. Joseph Thywissen (University of Toronto)
5s-6s two-photon and Stark-induced one photon spectroscopy in rubidium 15m
The ns → (n+1)s transition in alkali atoms is of interest due to its sensitivity to relativistic effects, and it has been the basis for the most stringent atomic parity non-conservation measurement by the Boulder group. We have carried out 5s→6s two-photon spectroscopy on rubidium kept in a vapor cell, with the aim of determining 6s hyperfine splittings and 5s→6s isotope shifts between isotopes 85 and 87 at the 100 kHz level, using RF sideband modulation techniques. In a next step, we will observe the Stark-induced one-photon 5s→6s transition in a vapor cell with internal field plates. The goal will be to determine the 5s→6s scalar and tensor transition polarizabilities. These measurements are precursors to equivalent measurements in laser-trapped francium atoms at TRIUMF. Supported by NSERC and the University of Manitoba.
Speaker: Kyle Shiells (U)
Ultracold Rydberg atoms and hybrid quantum systems 30m
Rydberg atoms --- large atoms with a highly excited, loosely bound electron --- may enable hybrid quantum systems, combining the long coherence times of atomic systems with the strong interactions of solid-state devices. However, this will require atoms to be located near a heterogeneous surface with exposed metal electrodes and dielectric insulators, which are sources of uncontrollable and unwanted electric fields. With this motivation, we have measured both the static [1] and time-varying [2] electric fields near the heterogeneous metal-dielectric surface of an atom chip using cold Rydberg atoms. We have also developed a technique for reducing the influence of dc and low-frequency electric fields on Rydberg atom transitions, while retaining their sensitivity to high-frequency resonant fields [3]. [1] J. D. Carter, O. Cherry, and J. D. D. Martin, Phys. Rev. A, v. 86, 053401 (2012) [2] J. D. Carter and J. D. D. Martin, Phys. Rev. A, v. 88, 043429 (2013). [3] L. A. Jones, J. D. Carter, J. D. D. Martin, Phys. Rev. A, v. 87, 023423 (2013).
Speaker: Prof. James Martin (University of Waterloo)
Isotope shifts in 206-213Fr and 221Fr from the Francium Trapping Facility 15m
The Francium Trapping Facility at TRIUMF has successfully commissioned a capture chamber and is in the process of completing a science chamber for weak interaction studies. We present recent isotope shift measurements of the 7S1/2 to 7P1/2 (D1) transition taken in the capture chamber by radiofrequency sideband spectroscopy. While isotope shifts in heavy elements are dominated by the field shift, caused by a change in nuclear charge radius, our new measurements are aimed at the extraction of another important and non-trivial contribution, the specific mass shift, which is sensitive to electron correlations. Thus we can benchmark predictions made from the atomic wavefunctions required for the interpretation of future francium parity non-conservation measurements. Taking our data along with literature 7S1/2 to 7P3/2 (D2) shifts in a King plot allows an extraction of the field shift constants ratio FD2/FD1 = 1.0520(10), comparing P3/2 and P1/2 electronic overlap with the nucleus. It also tells us the specific mass shift constants difference between these two transitions, SD2 - SD1(FD2/FD1) = 170(100) GHz amu.
Speaker: Mr Robert Collister (University of Manitoba / TRIUMF)
(W1-7) Cosmic Frontier: Dark Matter - PPD / Frontière cosmique: matière sombre - PPD C-112
Convener: Matthias Danninger (University of British Columbia (CA))
Searching for Dark Matter with PICASSO 15m
The Project In CAnada Searching for Supersymmetric Objects (PICASSO) at SNOlab searches for Weakly Interacting Massive Particle (WIMP) interactions with 19-F. It is particularly sensitive to spin-dependent particle interactions. It uses a droplet technique, based on the principle of a bubble chamber, in which phase transitions in superheated liquids can be triggered by WIMP induced nuclear recoils. The detection process allows a highly efficient suppression of backgrounds from cosmic muons, gamma rays and beta particles. In this talk recent progress and results will be presented, with particular focus on the 10 GeV low mass region, for both spin dependent and independent interactions.
Speaker: Dr Christopher Jackson (Université de Montréal)
Dark Matter Search with SuperCDMS 15m
It is well established by now that about 80% of the mass in the Universe exists in a form other than the baryonic matter that makes up all object we know. However, we do not know yet what this "Dark Matter" consists of. The most discussed solution to this problem is a Weakly Interacting Massive Particle (WIMP). SuperCDMS is an upgrade of the Cryogenic Dark Matter Search experiment using cryogenic detectors based on larger germanium single crystals (~0.6 kg per detector) with a new sensor layout which greatly improves the detector performance. This talk will introduce the new SuperCDMS detectors, discuss status and future of the experiment, and highlight the first results which break new ground in the low WIMP mass range.
Speaker: Wolfgang Rau (for the SuperCDMS Collaboration)
Data Acquisition for SuperCDMS-SNOLAB 15m
The Super Cryogenic Dark Matter Search (SCDMS) experiment uses solid state germanium and silicon detectors to search for Weakly Interacting Massive Particles (WIMPs), a leading candidate to explain dark matter. WIMPs are thought to be streaming through the earth, and CDMS seeks to measure the energy deposited by a WIMP-nucleon collision in sensitive calorimeters. Background particles dominate the potential WIMP signal, where a background rate of $\sim$0.2Hz due to $\alpha, \beta, \gamma,$ and neutrons is observed in each detector. This rate is 4 orders of magnitude greater than the WIMP event rate predicted by optimistic WIMP models. High statistics calibration runs with different radioactive sources are crucial to understanding the energy signature of background particles and to ensure that a background event will never be mistaken for a WIMP. Calibration runs involve higher event rates ($\sim$7Hz per detector) than WIMP search runs. We present a zero-dead-time Data Acquisition (DAQ) System that uses Detector Control and Readout Cards (DCRCs). These cards read in waveforms of an event from the detector's 12 phonon and 4 ionization energy channels and write the waveforms to a 3.3 second circular memory buffer. We design a DAQ system to decide, within this 3.3s window, which of the $\sim$140kB events to write to disk in order to keep data throughput under a limit and keep total data volume manageable for the later analysis. In this effort we use different readout methods for the different calibration runs and WIMP search runs. We discuss these methods and also discuss our pileup rejection cuts, which are designed to reject events with overlapping pulses that cannot be easily analyzed.
Speaker: Mr William Page (University of British Columbia)
State of the Art of Searches for Dark Matter 30m
Astronomical observations of galaxies, clusters of galaxies and studies of the large scale structure of the Universe show convincing evidence of the existence of dark matter (DM). However our understanding of its nature and its non-gravitational properties is still lacking. We will review the basic properties of dark matter, discuss the strategies employed for its observation and give an overview of the state of the art of ongoing direct and indirect dark matter experiments. Particular emphasis will be given to the discussion of recent intriguing results in this vibrant field of research.
Speaker: Prof. Viktor Zacek (Université de Montréal)
(W1-8) Energy Frontier: Exotics - PPD-DTP / Frontières d'énergie: exotiques - PPD-DPT C-203
Convener: Svetlana Barkanova (Acadia University)
No Stone Left Unturned? Searches for New Physics with ATLAS 30m
One of the key missions of the LHC is to search for the unknown and unexpected. The 2012 LHC run at centre of mass energy of 8 TeV has delivered a wealth of data for the ATLAS experiment to analyse. This talk will give a flavour of the variety and breath of searches for physics beyond the Standard Model at ATLAS, ranging from those using relatively clean signatures through to more complicated searches in final states containing top quark pairs, tau leptons and long-lived particles. A variety of different models are covered, from extensions to the SM that include new forces or new dimensions, to searches looking for tiny deviations from known processes.
Speaker: Dr Wojtek Fedorko (University of British Columbia)
How hard is it to get a de Sitter solution in String Theory? 30m
In this talk I will argue that a de Sitter solution in string theory is hard to get, although not impossible. I'll show a possible way to realize KKLT type solution using string theory fluxes and discuss the status of other possible ways to achieve de Sitter vacua.
Speaker: Prof. Keshav Dasgupta (McGill University)
The Search for a Heavy Higgs-like Boson in the WW(lvjj) Decay Channel with the ATLAS Detector 15m
The search for search for a heavy Higgs boson decaying into the semi-leptonic WW final state is presented in the high mass range (300 GeV - 1000 GeV) using the ATLAS detector. These results are based on the 2012 proton-proton dataset provided by the Large Hadron Collider (LHC) corresponding to an integrated luminosity of $21\ fb^{-1}$ at center of mass energy of $\sqrt{s} = 8\ TeV$. The search covers both Standard Model interpretations and theories beyond the Standard Model which predict a second Higgs in addition to the already discovered resonance at 125 GeV.
Speaker: Hass Abouzeid (University of Toronto (CA))
Search for new physics in the same-sign dilepton final states with the ATLAS detector at the LHC 15m
Many new physics models beyond the Standard Model produce same-sign dilepton pairs. Supersymmetry, universal etra dimentions, left-right symmetry, Higgs triplets and Little Higgs are examples of such new models. Same-sign dilepton pairs are clean signature in the collisions of two protons because not many Standard Model process to produce such final states exist. This makes it an ideal place to look for new physics. Using 20 fb-1 of 8 TeV data, we set limits on new physics cross sections, especially on doubly-charged Higgs production.
Speaker: Dr Kenji Hamano (University of Victoria)
CAP Teachers Workshop (Day 2) with SNOLAB Tour / Atelier des enseignants (Jour 2) avec visite guidée du SNOLAB F-536
(W-Pub) CAP Commercial Publishers' Session / Session des éditeurs commerciaux C-206-07
C-206-07
CAP Commercial Publishers' Session 45m
Join Dr. Marina Milner-Bolotin, to discuss how Physics Education Research and Modern Education Technologies can help you engage your undergraduate students in meaningful physics learning inside and outside of classroom. Presentation by Nelson Education followed by product demo and light refreshments in room C-207.
(W-PLEN1) Plenary Session - Gabriela Gonzalez, Louisiana State U. - Session plénière FA-054+5+6
Opening the gravitational wave window 45m
Gravitational waves are "ripples in space time'' produced by violent astrophysical events such as core-collapse supernova and collisions of neutron stars and black holes, as well as by other continuous phenomena as rotating stars and the early Universe. These waves have never been directly detected on Earth yet, but a network of LIGO and Virgo ground-based interferometric detectors is expected to do this very soon. These detectors have operated with record sensitivity in the recent past, and they are being upgraded to begin operating with good prospects of observations, to start operations in a few years. I will present a brief introduction to the nature and detection of gravitational waves, and present the current status of the international network of detectors, which will include new detectors in India and Japan.
Speaker: Gabriela González (Louisiana State University)
NSERC Presentation by Elizabeth Boston / Présentation du CRSNG par Elizabeth Boston FA-054+5+6
NSERC EG Chair Report (L.-H. Xu) / Rapport de la présidente du GE (L.-H. Xu) FA-054+5+6
12:15 PM → 12:30 PM
CAP-NSERC Liaison Committee Report (J. Dutcher) / Rapport du Comité de liaison ACP-CRSNG (J. Dutcher) FA-054+5+6
DCMMP Annual Meeting / Assemblée annuelle DPMCM F-336
DPE Annual Meetings / Assemblée annuelle DEP F-337
Convener: Calvin Kalman (Concordia University)
New Faculty Lunch Meeting with NSERC / Dîner-rencontre des nouveaux professeurs avec le CRSNG F-335
(W2-1) Low Dimensional Systems - DCMMP / Systèmes de basse dimension - DPMCM C-204
Convener: Manu Paranjape (Université de Montréal)
Andreev quantum dots in graphene/superconductor hybrid devices 30m
Although graphene is not intrinsically superconducting, Cooper pairs from a superconducting contact can diffuse through it. The superconducting proximity effect was observed experimentally in graphene Josephson junctions with contacts made of various superconducting materials like Al, Pb, Nb and even layered materials like NbSe$_2$ [1,2]. When the energy of the electrons in the graphene layer is below the superconducting gap of the contacts, they will be bound in the normal region. These are the well known Andreev bound states. We consider a graphene layer deposited on top of a superconducting surface such that the graphene layer can be considered to be partially freestanding and/or strained. It was recently shown that strain has a peculiar effect on the electronic properties in graphene, namely that it will coupled exactly like a gauge field [3,4]. Under certain conditions it is thus possible to have strong pseudo-magnetic fields and even pseudo-Landau levels coexisting with superconducting correlations [5]. By using an efficient numerical method [6] we solve the Bogoliubov-de Gennes equations for a tight binding model of the graphene layer. We show that in the regions where the sheet is freestanding, bound states due to Andreev reflections appear, thus forming Andreev quantum dots. We provide various ways to manipulate the energy states inside the dots, and further more devise inter-dot coupling. [1] H. B. Heersche, P. Jarillo-Herrero, J. B. Oostinga, L. M. K. Vandersypen, and A. F. Morpurgo, Nature (London) 446, 56 (2007). [2] A. Kanda, T. Sato, H. Goto, H. Tomori, S. Takana, Y. Ootuka, and K. Tsukagoshi, Physica C 470, 1477 (2010). [3] F. Guinea, M. I. Katsnelson, and A. K. Geim, Nat. Phys. 6, 30 (2009). [4] N. Levy, S. A. Burke, K. L. Meaker, M. Panlasigui, A. Zettl, F. Guinea, A. H. C. Neto, and M. F. Crommie, Science 29, 544 (2010). [5] L. Covaci and F. M. Peeters, Phys. Rev. B 84, 241401(R) (2011). [6] L. Covaci, F. M. Peeters, and M. Berciu, Phys. Rev. Lett. 105, 167006 (2010).
Speaker: Dr Lucian Covaci (University of Antwerp, Belgium)