text:
\section{Introduction}
\label{intro}
\begin{figure*}
\centering
\includegraphics[width = 1.0\textwidth]{hbar_setup_2_vector4}
\caption{Left: Breit-Rabi diagram showing the magnetic field dependence of the four hyperfine states of ground-state antihydrogen, as well as the two accessible transitions in ASACUSA ($\pi_1$ and $\sigma_1$). Right: sketch of the apparatus to measure the hyperfine structure of antihydrogen. Positrons are drawn in red, antiprotons in blue. The synthesised antihydrogen beam is marked in purple. Light purple shows high-field seekers (HFS) and dark purple the low-field seeking (LFS) component of the beam. The grey lines indicate the magnetic field lines of the double-Cusp magnet.}
\label{fig:setup}
\end{figure*}
The fundamental symmetry of CPT
is a pillar of the Standard Model with no violation observed so far \cite{Tanabashi:2018oca}. As a consequence matter and antimatter are predicted to have equal or sign-opposite intrinsic properties. Nonetheless, an asymmetry between matter and antimatter is observed in the universe \cite{Bennett:2003} and in spite of
CP violation measurements in mesons~\cite{CPKaons,CPBmes1,CPBmes2,CPDmes} and recent indications for CP violation in the leptonic sector~\cite{T2K-NeutrinoCP_2020}
to date quantitative explanations are missing.
This warrants precise measurements of antimatter properties, such as transition frequencies, to compare with their matter counterparts.
Theories beyond the Standard Model (such as string theory) allow a violation of the CPT symmetry at some level. In particular, the Standard Model Extension (SME) \cite{Colladay:1997vn,Colladay:1998,Kostelecky:2004} provides a general parameterisation of CPT violation and sensitivity guidelines for ato\-mic spectroscopy measurements and other experimental tests. The case of antihydrogen is discussed in dedicated publications in the minimal \cite{Bluhm:1999vq} and non-minimal \cite{Kostel2015} SME.

Antihydrogen ($\overline{\mathrm{H}}$) is the simplest stable atom composed solely of antimatter. Hydrogen, its matter counterpart, is one of the most precisely studied atomic systems. The hydrogen ground state hyperfine splitting (GS-HfS) of $\nu\approx 1.42$ GHz has been measured accurately by maser experiments with an absolute (relative) precision of 2 mHz  ($1.4 \times 10^{-12}$)~\cite{Hellwig1970,Karshenboim2000}.
Since a maser is currently not applicable to antimatter due to the necessary confinement of atoms in a matter enclosure, ASACUSA proposed an in-beam measurement of the GS-HfS of antihydrogen \cite{WidmannEtAl:2001,Widmann:2013,Malbrunot2017aa} and tested the method using a  beam of polarised hydrogen. This resulted in the most precise in-beam measurement of the hydrogen GS-HfS with a relative precision of $2.7 \times 10^{-9}$~\cite{Diermaier2017aa}.
Comparing  the hyperfine transition frequency of hydrogen and antihydrogen yields one of the most stringent tests of CPT \cite{Widmann:2018}.

The data presented in this paper were obtained at CERN's Antiproton Decelerator (AD) \cite{Baird:1996ofk}, where ASACUSA produced the first antihydrogen beam in 2012~\cite{Kuroda2014a}. We plan to measure the antihydrogen GS-HfS at CERN's new Extra Low ENergy Antiproton ring (ELENA) \cite{Chohan:2014bja}, initially with a relative precision of $\Delta \nu/ \nu \approx 10^{-6}$ by using the Rabi resonance method~\cite{Rabi1938a} in an antihydrogen beam. Fig.~\ref{fig:setup} (left) shows the Breit-Rabi diagram~\cite{Breit1931} which describes the behaviour of the four hyperfine states of antihydrogen in a weak external magnetic field. The total angular momentum quantum number $F$ and its projection on the quantisation axis $M_F$ are listed for each of the states. With ASACUSA's setup two transitions, $\sigma_1$ and $\pi_1$, are accessible and they are marked in the figure by arrows. The GS-HfS frequency can then be determined by measuring one of the transitions for several field strengths and extrapolating to zero field. Alternatively, it can be calculated by measuring both transitions at the same field strength~\cite{Juhasz2009,Kolbinger2015}.

The GS-HfS frequency of $\overline{\mathrm{H}}$ has been measured recently in a magnetic trap with  a relative precision of $\approx 4\times 10^{-4}$~\cite{Ahmadi2017}. However, trapping antihydrogen requires strong inhomogeneous magnetic fields which limits the experimental precision.
In particular, the $\pi_1$ transition frequency  ($F, M_F$: 1,-1 $\to$ 0,0),
which is sensitive to CPT violations within the SME framework~\cite{Kostel2015}, is prone to systematic biases due to its sensitivity to field inhomogeneities.
In ASACUSA the interaction region is a low magnetic field environment. By adequate shielding and correction coils the external magnetic fields can be reduced to $\lesssim 1 \, \mu$T~\cite{Thole:2016} with sufficient uniformity for the spectroscopy experiment.
Furthermore, the temperature of the $\overline{\mathrm{H}}$ beam can be relatively high (50~K to 100~K)~\cite{Malbrunot2017aa}, much in contrast to trapping experiments which require very cold antiatoms ($\lesssim 0.5$~K).
On the other hand beam formation and Rabi spectros\-copy are faced with other losses connected to acceptance of solid angle, velocities and quantum states. Therefore, some hurdles still need to be overcome in order to fully exploit this complementary approach.

Figure~\ref{fig:setup} (right) shows a sketch of the experimental setup to measure the GS-HfS. Antiprotons ($\overline{\mathrm{p}}$) from the AD are stored in the MUSASHI trap \cite{Kuroda:2012zza}. Positrons (e$^{+}$) are obtained from a $^{22}$Na source and a neon moderator then stored in the positron accumulator~\cite{Imao:2010zz}.
Together they form antihydrogen in the so-called double-Cusp trap~\cite{Mohri2003,Nagata2017aa}.
The double-Cusp trap consists of a multi ringed electrode trap \cite{Mohri_1998} housed within a magnetic field produced by a pair of superconducting coils in an antihelmholtz configuration. A nested penning trap is formed in a region of strong magnetic field before the first of two cusps (see figure \ref{fig:cusp} below) to mix positrons and antiprotons. The purpose of the cusped field is to focus and polarise cold ground state antihydrogen atoms, this is discussed in detail elsewhere \cite{Nagata2017aa}. In this work, it is expected that the antihydrogen formed will be hot hence the focusing and polarisation effect of this configuration will be mini\-mal \cite{Lundmark:2015}.
Details follow in Sect. 2.1.

The polarised $\overline{\mathrm{H}}$ atoms escape the trap and enter the spectrometer consisting of a microwave cavity \cite{Federmann2012,Malbrunot2019} to induce hyperfine transitions, and a state-analysing sextupole magnet.  In the Rabi-type
resonance method the force from magnetic field gradients exerted on the magnetic moments separates the $\overline{\mathrm{H}}$ atoms according to their spin states (Stern-Gerlach separation): the sextupole magnet focuses the low-field seeking states and defocusses the high-field seekers. A detector (see Sect.~\ref{sec:det}) records the annihilation signal at the end of the beamline as a function of the microwave frequency applied in the cavity. The challenge lies in producing an intense, focused and polarised source of $\overline{\mathrm{H}}$ atoms in their ground states.

This paper is organised as follows: Sect.~\ref{sec:exp} describes the experimental setup and Sect.~\ref{sec:ana} the analysis method for event identification and background rejection in the data recorded by the antihydrogen detector at the end of the beamline. The time distribution of the $\overline{\mathrm{H}}$ atoms arriving at the detector is described in Sect.~\ref{sec:timedist}. Finally, we  present in Sect.~\ref{sec:qdist} the first measurement of the distribution of the principal quantum number of the $\overline{\mathrm{H}}$ atoms exi\-ting the double-Cusp trap.

\section{Experimental setup}
\label{sec:exp}

\begin{figure*}
\centering
\includegraphics[width=\textwidth]{newsetup_10.pdf}
\caption{Longitudinal cut through of the double-Cusp trap (top), and electric potential (bottom) and on-axis magnetic field configuration (bottom).
 The multi-ring electrode (MRE) is drawn in gold, the superconducting anti-Helmholtz coils in light blue. The $\overline{\text{p}}$ and  $\text{e}^+$ enter from the left and the $\overline{\mathrm{H}}$ atoms exit to the right. The AMT detector around the mixing region is shown in dark blue. Mixing and field ionisation regions inside the Cusp (FI) are marked by the purple and grey shaded areas. The inset (rectangle) on the right shows the potential configurations used for the direct-injection mixing method \cite{Kuroda2014a}. The dashed blue arrow symbolises the injection of $\overline{\text{p}}$s, the solid blue line the $\overline{\text{p}}$s trapped in the nested well. The downstream beamline with the EFI chamber and the detector is also depicted.}
\label{fig:cusp}
\end{figure*}

To measure the quantum state composition in the antihydrogen beam we had to modify the apparatus foreseen for the HfS measurement. The $\overline{\mathrm{H}}$ beamline was shortened to increase the solid angle acceptance at the detector (Sect.~\ref{sec:prod}). The microwave cavity and sextupole magnet were removed and the antiproton annihilation detector was installed after the mixing trap (see Fig.~\ref{fig:cusp} below). The distance between mixing region and
the centre of the detector was $\approx$185~cm, corresponding to a solid angle of $\approx$0.015\% $\times 4 \pi$.
An external field ioniser (EFI)~\cite{Sauerzopf2016pro} was inserted between the mixing trap and the detector to deduce information on the principal quantum number distribution of the $\overline{\mathrm{H}}$ atoms emerging from the trap. Its distance to the production region in the double-Cusp trap is 140~cm where the residual magnetic field of the trap was measured to be $\approx$4 mT.
The EFI consisted of two parallel copper mesh-electrodes, perpendicular to the beam direction (see Fig.~\ref{fig:cusp}). The nominal value of the mesh distance was measured before closing the vacuum chamber to be $\geq 10.0$~mm and $\leq 10.5$~mm everywhere and is therefore assumed to be $10.25 \pm 0.25$~mm.

The voltage polarity was chosen such that antiprotons resulting from the ionisation were deflected in the upstream direction.
The quadra\-tic grid pattern of the meshes had a spacing of \unit[3.04]{mm} with a tines thickness of \unit[0.07]{mm} resulting in a total transparency of both meshes of 95\%.
However, the grid structure allowed for field penetration resulting in a weaker field than what would follow by dividing the voltage difference by the distance between the meshes. We have performed simulations using the finite element software COMSOL and see an average field, that is about \unit[9]{\%} weaker, see Table~\ref{tab:FI}.

\begin{table}
 \caption{EFI voltage settings and resulting averaged electric fields for minimal and maximal distance $d$ between the meshes. }
\label{tab:FI}
\begin{tabular}{ccccc}
\hline\noalign{\smallskip}
$\Delta U$ & $U_{1}$ &$U_2$ &  \multicolumn{2}{c}{$|E|$ (V/cm) for $d$ } \\
(kV) & (kV) & (kV) & 10.0 mm  & 10.5 mm   \\
\noalign{\smallskip}\hline\noalign{\smallskip}
10   & $+5$  & $-5$   & 9060  & 8629  \\
0.8   & $+0.4$ & $-0.4$  & 725   & 690   \\
0.14   & $+0.07$  & $-0.07$   & 127   & 121   \\
0.04    & $+0.04$  & $0$     & 36.2  & 34.5  \\
\noalign{\smallskip}\hline
\end{tabular}
\end{table}

The highest electric field ($E\approx$9~kV/cm) applied during our measurements could ionise substates of the $n$-manifolds down to $n=15$. Four different voltage settings were used to evaluate the quantum number distribution. They are listed in Table~\ref{tab:FI}.

\subsection{Production trap and antihydrogen synthesis}
\label{sec:prod}

The double-Cusp trap for mixing antiprotons and positrons consists of a multi-ring electrode (MRE) \cite{Mohri98} and two superconducting pairs of anti-Helm\-holtz  coils~\cite{Mohri2003,Nagata2017aa} (Fig. \ref{fig:cusp}). The latter provide the inhomogeneous magnetic field to polarise the $\overline{\mathrm{H}}$ atoms leaving the trap~\cite{Nagata2014a,Lundmark:2015} and focus the low-field seekers entering the spectroscopy section of the apparatus.
Fig.~\ref{fig:cusp} (bottom) shows the electric and magnetic field configurations  along the trap axis. In the mixing region positrons and antiprotons overlap in the nested potential well. A field ionising well in the double-Cusp (FI) is located downstream of the production region. Its electric field, as applied for most of the presented results (see Table \ref{tab:runs}), ionises $\overline{\mathrm{H}}$ atoms in higher Rydberg states~\cite{Kuroda2014a}. The resulting antiprotons are trapped in the well where they can be released later to estimate the number of  $\overline{\mathrm{H}}$ atoms which were field ionised.

The ASACUSA Micromegas Tracker (AMT) \cite{Radics2015} consists of a layer of scintillators sandwiched between two layers of Micromegas detectors, located between the magnet and the cold bore around the mixing region. The purpose of the AMT is to reconstruct the annihilation vertices in the trap~\cite{Mackel2018} and to distinguish annihilations on the MRE walls from those on the rest gas in the trap. Annihilations on the walls stem mostly from $\overline{\mathrm{H}}$ atoms which  are not confined by the electric and magnetic fields of the trap. Wall annihilations provide a complementary way to monitor the $\overline{\mathrm{H}}$ production process which is independent of quantum states and relies on radial escape.

The production of antihydrogen occurs in 15 to 20 minute cycles. The scheme employed for the presented data is that of direct injection~\cite{Kuroda2014a} of antiprotons
from the MUSASHI trap into a cloud of positrons
in the double-Cusp trap, the method that was  used first to produce antihydrogen in ASACUSA \cite{Enomoto:2010}.
Several stacks of positrons are collected and then transported to the mixing trap, where they are stored in the nested well potential. Twenty-five stacks are accumulated in the mixing trap, leading to a positron cloud with a radius of 0.9~mm and a density of $6 \times 10^8$ positrons/cm$^{3}$.
Typically four antiproton shots from the AD are accumulated and cooled in the MUSASHI trap ~\cite{Kuroda:2012zza}. About $6 \times 10^{5}$ antiprotons are then transferred adiabatically to the double-Cusp trap with an energy of 1.5~eV. They are directly injected into the positron cloud with a kinetic energy close to the potential energy of the $\text{e}^+$ plasma, and a narrow energy spread of $0.23 \pm 0.02$~eV~\cite{Tajima_2019}.

Antihydrogen can be formed via radiative and three-body recombination, where the latter dominates at the temperatures used in our experiment due to its higher cross section~\cite{Gabrielse1988a}. The subsequent evolution of state population is determined by collisional deexcitation and ionisation~\cite{robi2008,Radics2014}.

\subsection{Antihydrogen detector}
\label{sec:det}

The  detector at the end of the beamline is composed of a central BGO (bismuth germanate) crystal
 which measures the energy deposited by the $\overline{\mathrm{H}}$ annihilation,  surrounded by a tracking detector to detect the charged annihilation products (mainly pions). A drawing of the detector is shown in Fig.~\ref{fig:det}.

\begin{figure*}
\centering
\includegraphics[width=0.8\textwidth]{detector_no_fibres_fig_bk_new.pdf}
\caption{Left: side-view of the  $\overline{\mathrm{H}}$ annihilation detector showing the scintillator bars and BGO crystal in  blue, and the multianode photomultipliers (MAPMT).  Right: $x-y$ cross section of the detector used for online event monitoring, showing a candidate antihydrogen annihilation. The coloured hodoscope bars report channels with  hits. The pixel map in the centre shows the read-out of the MAPMTs. The white circle indicates the position of the BGO crystal.
}
\label{fig:det}
\end{figure*}
The BGO crystal is a disk, 90~mm in diameter and 5~mm thick~\cite{nagataBGO,nagataBGO3}, enclosed in a vacuum vessel kept at UHV pressure. The upstream face of the crystal is coated with a 0.7~$\mu$m carbon layer applied by sputter deposition. The carbon layer improves the position resolution of the annihilation point by absorbing the  light reflected back from the downstream face of the crystal. The scintillation light is detected by four Hamamatsu H8500 multianode photomultiplier tubes (MAPMT), placed outside the vacuum and separated from the BGO by a UHV viewport. Each MAPMT is sensitive to an effective area of $49 \times 49$~mm$^2$ (8$\times$8 readout channels). The signals are charge-amplified, digitised and read out by amplifier units mounted directly on the MAPMTs.
The energy calibration of the BGO crystal is discussed in~\cite{Nagata2018bb}, where details can be found.

The surrounding tracking detector is composed of two layers of each 8 $\times$ 4 plastic scintillator bars (material EJ-200) along the beam direction, arranged octagonally~\cite{Sauerzopf2016bb}. The inner bars are 300~mm long and 20~mm wide, the outer ones 450~mm long and 35~mm wide. Inner and outer bars are 5~mm thick. The dia\-meter of the inner layer is 200~mm, that of the outer one 350~mm. Both layers cover a solid angle of $\approx 80$ \%$\times 4\pi$, seen from the centre of the BGO crystal. The light guides glued on both ends of the bars are connected to  pairs of silicon photomultipliers (KETEK 3350TS SiPM), read out by self-developed front-end electronics \cite{ifes},
which provide analogue and digital time-over-threshold signals for all 128 channels. The analogue waveforms are recorded by waveform digitisers (CAEN V1742). The constant fraction time stamps are calculated with the ASACUSA waveform library~\cite{wave}.

The timing information is calculated from the time difference between two bars~\cite{Sauerzopf2016bb}. This helps to distinguish between annihilation events from inside the detector and the external background, such as traversing cosmic rays. The resolution in the time difference between two bars has been measured to be $497 \pm 3$~ps and $551 \pm 5$~ps (full width at half maximum) for the inner and the outer layer, respectively~\cite{Sauerzopf2016bb}. The corresponding hit resolution along the detector axis, given by the time difference between the two ends of the bars, is 59 mm for the inner layer and 73 mm for the outer layer (full width at half maximum)~\cite{KolbingerThesis}.

\section{Event analysis}
\label{sec:ana}

A machine learning analysis was developed to discriminate $\overline{\mathrm{H}}$ annihilation events from back\-ground and to accurately measure the number of atoms reaching the detector~\cite{KolbingerThesis}. The analysis is based on the supervised method gradient-boosted decision trees\footnote{Library XGBoost~\cite{Chen2016}.} (GBDT) and is trained with measured data. The following sections describe the performed steps of constructing and optimising the event classification analysis: selecting the data set (Sect.~\ref{sec:data}), choosing the discriminating variables (Sect.~\ref{sec:features}) and hyper-para\-meter tuning (Sect.~\ref{sec:parameter_opt}).

The evaluation of the algorithm is done via several iterations of training and testing. The model is built in the training step with $\frac{2}{3}$ of the events in the data set, and then tested with the remaining events. Based on its response to the test data, the resulting background rejection $\varepsilon_{\text{c}}$ and signal efficiency $\varepsilon_{\overline{\text{p}}}$ are calculated.
Details of the training and evaluation procedure of the algorithm and the  selection of antihydrogen candidate events is described in Sect.~\ref{sec:event_select}.
The performance of the algorithm is measured via the area under the Receiver-Operating-Characteristics \-(ROC) curve -- the function $\varepsilon_{\text{c}}$ vs. $\varepsilon_{\overline{\text{p}}}$ -- denoted as $A_{\text{ROC}}$ in the following.

\subsection{Data selection and preparation}
\label{sec:data}

The GBDT analysis is trained with measured data consisting of a background and a signal data sample.
The background is mostly governed by cosmic ray events. The background sample comprises about 3$\times 10^5$  events which have been recorded over a week with beam off. This data sample is free from background occurring during $\overline{\mathrm{H}}$  data taking which originates from annihilations  upstream of the detector. The trigger rate was $f_{\text{c}} = 0.4687$~Hz.

Upstream annihilations are not taken into account. These events share all characteristics with annihilations on the detector, apart from their upstream vertex locations (and the lower multiplicity due to the smaller solid angle).
It was therefore more efficient to  determine the vertex of events after they had been selected by the machine learning analysis.
\begin{figure*}
\centering
\includegraphics[width=0.8\textwidth]{2016_data_BGO_vertex_17bins_both.pdf}
\caption[]{Two-dimensional histograms of hit positions on the BGO determined by the cluster finding algorithm (for the number of entries in the two-dimensional bins see the colour bar on the right sides of the plots). Left: cosmic ray events. Right: antiproton events. The red ellipse shows the applied cut on the antiproton hit positions for the events included in the signal data sample.}
\label{fig:bgohitpos}
\end{figure*}

Since the antiproton annihilation signature in the ASACUSA detector is identical to the one of antihydrogen atoms and the available number of antihydrogen events is  small, antiproton annihilations are used to train and test the algorithm.
The signal data sample consists of about 6500 antiproton annihilations that have been recorded in dedicated runs.
Antiprotons of a single AD shot are first trapped and cooled in the MUSASHI trap, before being slowly extracted with 150~eV~\cite{Kuroda:2012zza}. The antiprotons are then transferred through the double-Cusp trap with multi-ring electrodes groun\-ded. The magnetic field of the pair of anti-Helmholtz coils guides the antiprotons towards its exit and the detector. A fraction is defocussed when passing the zero $B$-field regions in the trap and annihilates on the MRE walls.

Due to the possible contamination of the signal data set, careful cuts on  the recorded antiproton data are applied to reduce residual background events.
The following cuts were applied: (1) a cut on the arrival time of events since the slow-extracted antiprotons arrive in a time window of $\approx$4~s length at the detector, (2) events with several spatially separated hits on the BGO are removed due to the possibility of being upstream annihilations i.e. pions from  annihilations on the beam pipe upstream of the detector. Due to the broad and off-centre distribution of annihilation points on the detector, an additional cut (3) on the hit position in the BGO is applied to reduce background contributions. Firstly, a cluster finding algorithm is applied on the two-dimensional $16 \times 16$ pixel read-out of the MAPMTs~\cite{KolbingerThesis}.
The antiproton hit point on the BGO is  defined as the mean of the pixel positions in the largest cluster, weighted by the energy of the pixels.

Fig.~\ref{fig:bgohitpos} shows two-dimensional histograms of the hit points on the BGO for cosmic rays (left) and for antiprotons (right). While for cosmics the hit positions are uniformly distributed, most antiprotons hit the BGO on the bottom side.
This is most likely due to a misalignment between the double-Cusp trap with respect to the downstream beamline.
The red ellipse in the right plot encloses the hit pattern of the  antiprotons and shows the selected cut to reduce the background contribution in the data.

The remaining number of cosmic ray events in the signal sample after cuts has been estimated by considering the total recorded time of antiprotons $t_{\overline{\mathrm{p}}}$ = 372 s (4 s $\times$ 93 runs) and hit area $A_{\text{hit}}$ (the area of the red ellipse in Fig.~\ref{fig:bgohitpos}, right). The residual cosmic contribution was therefore calculated by $f_{\text{c}} t_{\overline{\mathrm{p}}} \frac{A_{\text{hit}}}{A_{\text{BGO}}}$ with the rate of the cosmic events $f_{\text{c}}$ and $A_{\text{BGO}}$ the area covered by the BGO. It amounts to  0.37$\%$ of the total number of events in the signal data sample and is therefore negligible.

It is important to emphasise, that no cuts have been made on event features that will later be used in the machine learning procedure. No cuts have been applied on the cosmic background sample.

The number of events in the cosmic data set exceeds the number of events in the antiproton data set. Therefore, the balance between the two training sets is ensured by a combination of under- and over-sampling to avoid a biased model.  Initially, the cosmic events of the training sample are randomly under-sampled to 40$\%$ of their total number. Subsequently, the antiproton training data is over-sampled to match the size of the under-sampled cosmic data set. For this purpose, SMOTE (synthetic minority oversampling technique)~\cite{Chawla2002} implemented in the python package imbalanced-learn~\cite{Lemaitre2001} is employed. We emphasise that re-sampling is only applied to the training data. The test data, which are used to deduce cosmic rejection and antiproton efficiency, stay untouched.

\subsubsection{Antihydrogen data preparation}
\label{sec:hbarprep}

During antihydrogen productions runs  the mini\-mal event trigger condition was a hit in the BGO. The antiproton and cosmic data described above were recorded with combined hodoscope and BGO triggers, requiring a hit in the BGO and at least one hit in each hodoscope layer. A hodoscope bar is considered to have a hit if both up- and downstream SiPMs show a signal in coincidence.
To ensure consistency of the input distributions of training and antihydrogen data, the hodoscope trigger condition
was applied by software to the antihydrogen data after acquisition. The hodoscope trigger is generated by a CAEN V1495 FPGA if one of the inner and one of the outer bars show a digi\-tal signal from the up- as well as from
the downstream SiPMs. The digital signals are produced with a leading edge discriminator. All 128 analogue signals are recorded by waveform digitisers.
 The appropriate software cuts on the recorded amplitudes of the hodoscope bars were determined by studying two sets of cosmic data, one with BGO trigger only and one with both detectors in the trigger. Cuts on the first data set were varied and finally chosen such that the event rate of the data set recorded with the combined trigger was reproduced.

\subsection{Discriminating variables and feature selection}
\label{sec:features}
\begin{figure*}
\centering
\includegraphics[width=0.85\textwidth]{top_features_5.pdf}
\caption{Distributions of the three most important features for  antiproton annihilations (I) and cosmics (II). A: $\alpha_{\text{max}}$; B: $E_{\text{BGO}}$, the inset shows the contribution from antiprotons corrected  for cosmic background (III) which affects mainly the 0 -- 20 MeV region; C:  t$_{\text{ToF}}$ with averages and standard deviations for antiprotons and cosmics. The cosmics histogram is scaled to the acquisition time and hit area of the antiproton events. Histograms in A and C are normalised to their area. }
\label{fig:features}
\end{figure*}
The number and choice of discriminating variables, also called input features in the following, is crucial when using finite data sets, due to the increasing sparsity of the training data with higher dimensionality.
Twelve potential input features for the analysis have been investigated:
\begin{enumerate}
\item[--] The energy deposit in the central BGO calorimeter $E_{\text{BGO}}$, given by the sum of the output of the MAPMT channels. Details on the energy calibration of the detector can be found in~\cite{nagataBGO3} and \cite{nagataBGO2}.

\item[--] The number of hits in the inner and outer hodoscope ($n_\text{I}$ and $n_\text{O}$).
\item[--] The number of tracks $N_{\text{tr}}$ in the hodoscope,  which is determined using the $x-y$ information of the bar hodoscope perpendicularly to the beam axis. The algorithm is similar to a Hough transformation and details are described in~\cite{KolbingerThesis}.
\item[--] The time-of-flight $t_{\text{ToF}}$ is given by
\begin{equation}
t_{\text{ToF}} = \sqrt{\frac{1}{N_{\text{tr}}-1} \sum\nolimits_{n=1}^{N_{\text{tr}}} (t_{n} - \overline{t})^2},
\end{equation}
where $t_n = \frac{1}{2}(m_{\text{I},n} + m_{\text{O},n})$ with $m_{\text{I},n}$ and $m_{\text{O},n}$ the average of all mean times of bars belonging to track $n$ in the two layers I and  O, and where $\overline{t}$ is the mean of all $t_n$'s. Annihilation events stem from inside the detector and their annihilation products traverse the hodoscope at approximately the same time, while $t_{\text{ToF}}$ is considerably larger for cosmic rays crossing the detector.
\item[--] The largest angle $\alpha_\text{max}$ between tracks in an event  and the second and third largest angles ($\alpha_\text{2}$ and $\alpha_\text{3}$).
\item[--] The mean $\alpha_\text{Y}$ of all angles between the tracks and the vertical axis.
\item[--] The number $N_\text{h}$ of horizontal tracks and the number of tracks in the upper and lower hodoscope halves, $N_\text{u}$ and $N_\text{d}$ respectively. A track is classified as being horizontal if it traverses the left and right side bars of the hodoscope.
\end{enumerate}
Some of these features cannot be calculated for all events. For example,   $t_{\text{ToF}}$ and the angles can only be calculated for events with $N_{\text{tr}} >$ 1. Here, the ability of the chosen algorithm to treat missing values in the feature vector becomes important.

In order to find the best combination and number of input features, the SFFS (Sequential Floating Forward Selection)~\cite{featselect} method is employed\footnote{The implementation of the python package MLxtend (Machine Learning extensions)~\cite{Raschka2018} was used.}. SFFS is a wrapper feature selection method that optimises the performance of the  model chosen (GBDT in this case) by exploring different feature sets. SFFS starts from an empty set and with every iteration adds the feature that results in the largest increase of $A_{\text{ROC}}$, until all twelve features have been added.
The highest $A_{\text{ROC}}$ is achieved with nine features and the following combination of features listed in order of addition by SFFS: $\alpha_{\text{max}}$, $E_{\text{BGO}}$, t$_{\text{ToF}}$, $\alpha_\text{Y}$, $n_\text{O}$, $\alpha_3$, $n_\text{I}$, $N_\text{h}$ and $N_{\text{tr}}$. The features $\alpha_{\text{max}}$, $E_{\text{BGO}}$ and t$_{\text{ToF}}$ have therefore the highest importance for separating signal from background. Their distributions of cosmic rays and antiproton annihilations are compared in Fig.~\ref{fig:features}.

\subsection{Parameter optimisation}
\label{sec:parameter_opt}

Hyper-parameters define the architecture of a model and they need to be fixed prior to trai\-ning. Examples are the number of trees in the ensemble, or the maximum depth of a tree. Those parameters are optimised to achieve the best performance. The set of parameters corresponding to the maximum $A_{\text{ROC}}$ of the multi-dimensional space of hyper-parameters needs to be found, which involves many model evaluations. Depending on the training time and the number of hyper-parameters, conventional methods, such as grid search, can quickly become too time consuming.

\noindent
For the current analysis, the hyper-parameters have been tuned by utilising the sequential mo\-del-based Bayesian optimisation technique  Tree-Parzen Estimator (TPE)~\cite{Bergstra2011,Bergstra2015}. These methods choose the parameter set to be subsequently explored by taking into account past trials and therefore focusing on promising areas of parameter space. Details on TPE and Bayesian optimisation methods can be found in the literature ~\cite{Bergstra2011,Bergstra2015}.
The set of found hyper-parameters~\cite{KolbingerThesis} is used throughout all training and evaluation steps in the analysis.

\subsection{Evaluation procedure and selection of antihydrogen candidate events} \label{sec:event_select}

The experimental data set containing antiproton and cosmic ray events was randomly split into a training set which comprised $\frac{2}{3}$ of the data, the remainder was kept to test the model built and to measure its response to unknown events. The model returns a prediction score for each event, a number between 0 and 1, where a value close to zero indicates a cosmic-like event and values close to 1 an antiproton-like event. This procedure was repeated a few hundred times with randomly selected training and test sets and the final results determined by averaging over the individual outcomes.

The average ROC efficiency $\varepsilon_{\text{c}}$ vs. $\varepsilon_{\overline{\text{p}}}$ is displayed in Fig.~\ref{fig:roc}, compared to a random guessing algorithm.
The average $A_{\text{ROC}}$ of a random guessing algorithm is equal to 0.5, while we obtain $0.9840 \pm 0.0015$ in our analysis~\cite{KolbingerThesis}. Our method has been benchmarked by comparing its results to an ensemble of simple rectangular cuts\footnote{ROOT's TMVA~\cite{tmva} was used.}  which yielded an $A_{\text{ROC}}$ of 0.84, showing that our multivariate analysis leads to a signi\-ficant improvement.

An operating point on the ROC needs to be chosen in order to determine cosmic rejection and antiproton efficiencies. This is done by fixing a cut on the prediction score of events and classifying events with a score below the cut value as background events and those with a score above as annihilation events.
The antiproton efficiency $\varepsilon_{\overline{\text{p}}}$ and cosmic rejection efficiency $\varepsilon_{\text{c}}$ are then calculated as the ratio of correctly classified events to the total number of events in the test data sets. The false positive rate $f_{\text{fp}}$ is then given by $f_{\text{fp}} = (1 - \varepsilon_{\text{c}}) f_{\text{c}}$, with the rate of cosmic rays equal to $f_{\text{c}} = 0.4687$~Hz.

\begin{figure}
\centering
\includegraphics[width=0.4\textwidth]{xgb_cosrej_vs_pbareff_2.pdf}
\caption{The average ROC of our analysis compared to the ROC of a random guessing algorithm.}
\label{fig:roc}
\end{figure}

The operating point on the ROC curve was chosen by optimising the significance of the $\overline{\mathrm{H}}$ candidate events found ($N_{\text{obs}}$) with respect to the remaining background ($N_{\text{b}}$) events after analysis. The probability to obtain a larger number $N$ of events than the observed $N_{\text{obs}}$ ($p$-value) is calculated using Poisson statistics~\cite{Behnkea}:
\begin{equation}
\label{eq:pval}
\begin{split}
p = P(N  \geq N_{\text{obs}}|N_{\text{b}}) & = 1 - F_{\text{Poisson}}(N_{\text{obs}}, N_{\text{b}}) \\
& = 1 - \sum^{N_{\text{obs}}}_{k=0} \frac{e^{-N_{\text{b}}}N_{\text{b}}^k}{k!},
\end{split}
\end{equation}
where $F_{\text{Poisson}}$ denotes the cumulative distribution function of the Poisson distribution. The $p$-value can then be translated into the observed significance by $s = F^{-1}_{\text{normal}}(1 - p)$, where $s$ denotes the significance in numbers of $\sigma$ and $F^{-1}_{\text{normal}}$ the inverse cumulative function of the standard normal distribution.

\begin{table*}
 \caption{EFI voltage difference $\Delta U$, status of the field ioniser in the double-Cusp trap, number of mixing runs (\# runs), number of $\overline{\mathrm{H}}$ candidates ($N_{\text{obs}}$), false positives ($N_b$) within 6~s after mixing start, $n_{\text{threshold}}$ and $n_{100\%}$ (see Section \ref{sec:qdist}).
   }
\label{tab:runs}
\begin{tabular}{cccccccc}
\hline\noalign{\smallskip}
$\Delta U$ (kV)  & Cusp FI & \# runs  & $N_{\text{obs}}$ & $N_{\text{obs}}$/run &  $N_{\text{b}}$ & $n_{\text{threshold}}$ & $n_{100\%}$  \\
\noalign{\smallskip}\hline\noalign{\smallskip}
10  & ON & 43  &  17  &  0.395  &   $1.979 \pm 0.374$ &  15  & 19  \\
0.8  & ON & 31 &  19  &  0.613  &   $1.427 \pm 0.270$ &  29   & 39  \\
0.14 & ON &16 &  27  &  1.688  &   $0.737 \pm 0.139$ & 46   & 62  \\
0.04  & OFF & 24  &  54  &  2.250  &   $1.105 \pm 0.209$  & $>$60   & $>$60  \\
\noalign{\smallskip}\hline
\end{tabular}
\end{table*}

By optimising the significance of the antihydrogen candidates found, we obtain $\varepsilon_{\text{c}}$ =  $0.9836 \pm 0.0031$ and $\varepsilon_{\overline{\text{p}}}$ = $0.800 \pm 0.0111$, with the false positive rate $f_{\text{fp}}$ = $0.0077 \pm 0.0015$~Hz.

The numbers $N_{\text{obs}}$ of $\overline{\mathrm{H}}$ candidates are summarised in Table~\ref{tab:runs} as a function of field ioniser (EFI) voltage setting. Note that for the lowest voltage setting of the EFI, the FI in the double-Cusp trap was not used. The numbers of runs per EFI voltage setting are listed in column 3 of Table~\ref{tab:runs}. A total of 114 mixing runs were performed to measure the quantum state distribution.  A run was typically 25~s long,  the period from mixing start -- when antiprotons are injected into the positron plasma -- to the time when they are dumped. A total of 159 $\overline{\mathrm{H}}$ candidates were found, but most antihydrogen candidates however arrive within the first 6~s, see the next section. Table~\ref{tab:runs} lists the 117 candidates arriving within the first 6~s after mixing start.

A second, independent analysis for signal and background discrimination has been carried out in ASACUSA, see Ref.~\cite{Nagata2018bb} and it is based on two dimensional cuts on event features and does not employ machine learning. A similar detection efficiency of $\tilde{\varepsilon}_{\overline{\text{p}}} = 81\%$ is achieved, the false positive rate is however almost twice as large with 0.012~Hz which demonstrates the effectiveness of a data-driven multivariate analysis.
Furthermore, the analysis~\cite{Nagata2018bb} is based on Geant4 Monte-Carlo simulations. Since discrepancies of multiplicities and energy deposit between Geant4 simulation results and measured data for low energy antiproton annihilations has been observed previously~\cite{aegisEdep,aegisMult1}, the two analyses are not directly comparable.

\begin{figure*}
\centering
\includegraphics[width=\textwidth]{time_dist_both_E_2.pdf}
\caption{A: Distribution of the arrival time of $\overline{\mathrm{H}}$ at the detector after mixing start. The bin width is 1~s and the error bars are Poisson errors.  B: Cumulative arrival time distribution for the four different EFI settings (colour-coded). The solid lines refer to the total counts per run. The cosmics corrected counts are shown by dashed lines.}
\label{fig:t_dist}
\end{figure*}

\section{Time distribution}
\label{sec:timedist}

The arrival time of the $\overline{\mathrm{H}}$ atoms at the detector gives valuable insight into the  $\overline{\mathrm{H}}$ production process. Fig.~\ref{fig:t_dist}A shows the arrival time distribution of the 159 $\overline{\mathrm{H}}$ candidates after mixing start. Most events are detected within the first few seconds, 74\% arriving at the detector in the first 6~s. This is most likely due to an axial separation of the antiproton and positron plasmas.

Fig.~\ref{fig:t_dist}B shows the time behaviour of the cumulative counts for the data sets recorded with different EFI settings. The continuous lines show the total cumulative counts and the dashed lines the cosmic background corrected counts. The steepest increase is always observed within the first few seconds after which the dashed line becomes flat, indicating a negligible number of $\overline{\mathrm{H}}$ reaching the detector.

\begin{figure}
\centering
\includegraphics[width=0.45\textwidth]{time_vs_pval_all.pdf}
\caption{$p$-value of $\overline{\mathrm{H}}$ candidates (all EFI runs) vs. time after mixing. The lowest $p$-value at 6~s is marked by the vertical dashed line.}
\label{fig:t_pval}
\end{figure}

For further analysis a cut on the arrival time is applied, motivated by the observed steep drop of $\overline{\mathrm{H}}$ production after a few seconds. The $p$-value of the observed $\overline{\mathrm{H}}$ counts is calculated via Equation~\ref{eq:pval} for various time intervals. The smallest $p$-value is found with a time interval of 6~s after mixing start (Fig.~\ref{fig:t_pval}).

\section{Quantum state distribution}
\label{sec:qdist}

\begin{figure*}[h]
\centering
\includegraphics[width=0.8\textwidth]{q_dist_counts_vs_E_log_2.pdf}
\caption{Number of $\overline{\mathrm{H}}$ candidate events per run for the four field ioniser settings listed in Table~\ref{tab:FI} (red crosses).
The mean value of electric fields for $d = 10.25$~mm is plotted as the $x$-coordinate of the crosses. The boundaries of the $x$-error bars correspond to $d=\unit[10]{mm}$ and $d = \unit[10.5]{mm}$.
$y$-error bars show Poisson errors. The estimated background per run is displayed with horizontal, black bars for each of the four field ioniser settings.}
\label{fig:q_dist}
\end{figure*}

The number of $\overline{\mathrm{H}}$ candidate events per field ioniser setting as well as the estimated small cosmic background  is plotted in Fig.~\ref{fig:q_dist}.
The distribution of recorded counts at the detector as a function of the electric field at the field ioniser can be used to extract some information on the quantum state distribution of the antihydrogen escaping the formation region toward the detector.
Field ionisation of hydrogen atoms in a static electric field has been discussed in detail in many references (e.g. \cite{Gallagher94} and reference therein).
The classical treatment puts in evidence a saddle point created by the application of the electric field to the purely coulombian potential leading to a electric field threshold beyond which a level is ionised.
However, the effective potential energy of the Rydberg electron in hydrogen also includes a centrifugal term due to its angular momentum along the quantisation axis \cite{PhysRevA.17.1226} so that for a given excitation energy, states of higher angular momentum will be harder to ionise.
Since we do not know a-priori the sub-level population of the antihydrogen formed within a given manifold, the information given in Fig.~\ref{fig:q_dist} can only be used to provide a range of $n$-manifolds probed for each field ioniser setting.
The quantum mechanical treatment of field ionisation leads to the observation that the lower-lying Stark state (so-called red state) has a maximum electron probability density near the saddle point and thus exhibits large ionisation rates at the ionisation threshold predicted by classical over-the-barrier theory, while the highest-lying state (blue state) has a low density close to the saddle point and thus ionises at higher electric fields. The ionisation threshold for the blue and red states of each $n$-manifold thus gives the minimum electric fields needed to, respectively, start ionising and fully ionise the given $n$-mani\-fold.

The quantum calculations do not predict an ionisation threshold but provide instead a field-ionisation rate.
The probability of observing an ion from a given state  depends on the ionisation rate and the transit time through the field (i.e. the $\overline{\mathrm{H}}$ velocity). The targeted tempe\-rature in this experiment is \unit[50]{K} but there is, as of yet, no measurement of the temperature of the antihydrogen formed with this scheme. Based on simulation \cite{Jonsell_2019} we assume the minimum kinetic energy of the antihydrogen atoms formed to be around \unit[0.001]{eV} but studied the impact on the quantum number addressed if the kinetic energy was up to four orders of magnitude higher. For ionisation occurring while atoms traverse the $\sim\unit[10]{mm}$ field ioniser, this range of energies corresponds approximately to a range $\sim\unit[10^5]{s^{-1}}- \unit[10^7]{s^{-1}}$ in ionisation rate.

We used the asymptotic semi-empirical ionisation rates formula provided in \cite{Damburg_1979}  to calculate the level width of all sub-states for the $n$-manifolds between $10<n<65$ since our lowest field ioniser setting ($\sim\unit[40]{V/cm}$) starts probing the region $n\sim60$. This formula makes use of the energy of each level calculated by perturbation expansion up to fourth order \cite{bordas_1993} and was checked against exact numerical calculations \cite{Damburg_1976} for different sub-levels up to $n=30$.
However, the residual magnetic field at the location of the field ioniser which is mostly parallel to the electric field and of magnitude $B\sim\unit[4]{mT}$, which we thus considered negligible for low $n$, will start playing a role for high $n$-states. Effects from non-adiabatic coupling of high $n$-states will also affect the ionisation rates~\cite{PhysRevA.23.1127}.
Thus, the formula we used will only give an approximate range of ionisation for high $n$-states.
We provide in Fig.~\ref{fig:n-vs-E-FI} (left) an example of the fraction of states of the different $n$-manifolds which would be ionised in a $\sim\unit[9]{kV/cm}$ field at the rates of $\unit[10^5]{s^{-1}}$ and $\unit[10^7]{s^{-1}}$.

As mentioned already, since we do not know the antihydrogen sub-level distribution, we use such plots to provide for a given electric field the highest state which can pass the field ioniser region without being ionised ($n_{\text{threshold}}$) and the lowest state which is fully ionised ($n_{100\%}$).
We provide in Fig.~\ref{fig:n-vs-E-FI} (right) the $n_{\text{threshold}}$ and $n_{100\%}$ as a function of the electric field up to $n=65$.
The uncertainty on the electric field strength, for the parameters considered, contributes similarly to the uncertainty in $n_{\text{threshold}}$ and $n_{100\%}$ as the range in ionisation rates.

 Fig.~\ref{fig:n-vs-E-FI} shows that the highest field ioniser setting ($\sim\unit[9]{kV/cm}$) can ionise down to the $n=15$ manifold.

\begin{figure*}[h]
\centering
\includegraphics[width=1.0\textwidth]{nManifoldsFieldIonization.pdf}
\caption{Left: Fraction of the states of an $n$-manifold ionised at an electric field of $\sim\unit[9]{kV/cm}$ ($\Delta U=\unit[10]{kV}$) for the two extreme cases of an ionisation rate of \unit[10$^5$]{s$^{-1}$} at $d=\unit[10.0]{mm}$ (thick line) and \unit[10$^7$]{s$^{-1}$} at $d=\unit[10.5]{mm}$ (thin line) calculated using the asymptotic semi-empirical ionisation rates formula provided in \cite{Damburg_1979}. Right: $n_{\text{threshold}}$ and $n_{100\%}$ for ionisation rates of \unit[10$^5$]{s$^{-1}$} (thick line) and \unit[10$^7$]{s$^{-1}$} (thin line). For three voltage settings on the EFI vertical lines mark the range of the resulting electric fields. In both figures three regions indicate in different shades of grey, where $n$-manifolds are not, partly, or entirely ionised.}
\label{fig:n-vs-E-FI}
\end{figure*}

In Table \ref{tab:runs}, we provide the approximate range of $n_{\text{threshold}}$ and $n_{100\%}$ probed for each field ioniser setting stressing again that for high $n$ this range is an indication rather than an accurate statement. The results presented here update the analysis published in \cite{Malbrunot2017aa} and the interpretation of the results which ignored the Stark shift of the Rydberg states and thus assumed a classical field for ionisation of $E=1/16n^4$ to estimate the lowest $n$-manifold probed by each field ioniser setting.

\section{Conclusions}
\label{sec:sum}

A beam of antihydrogen atoms was produced by injecting antiprotons into positrons in a nes\-ted Penning trap. To distinguish between annihilation events and background events recorded downstream by the $\overline{\mathrm{H}}$ detector, a data-driven machine learning analysis was developed. The resulting $\overline{\mathrm{p}}$ efficiency is $0.800 \pm 0.011$ and the cosmic rejection $0.983 \pm 0.003$. The false positive rate amounts to ($0.008 \pm 0.002$)~Hz.

Information on the quantum state distribution was deduced using a field ioniser placed in a low magnetic field region, 140~cm downstream of the production region.
We found 117 $\overline{\mathrm{H}}$ candidates in 114 mixing attempts with different field ioniser voltage settings during the first 6~s after mixing start, which is the time interval when most candidate events were observed.

The distribution of principal quantum numbers of the antihydrogen atoms shows that a higher fraction of atoms reaching the entrance of the spectroscopy beamline are in Rydberg states.

The observed production rate of atoms in the lowest lying states ($n_{\text{threshold}} = 15$ and $n_{100\%} = 19$) which are most interesting for ground state hyperfine spectroscopy, amounts to $0.395 \pm 0.096$ per run with an observed significance of 6.8~$\sigma$.
The average spontaneous decay time to ground state from the $n=19$ state assuming equi-popula\-tion of its sub-states is $\sim\unit[130]{\mu s}$ \cite{wolz:2019}. Assuming an average velocity of approximately 1000~m/s (temperature of \unit[50]{K}) -- which is the acceptance limit of our spectroscopy apparatus --
the antiatoms are likely to decay to the ground state before entering the microwave cavity (except for antiatoms decaying to the metastable 2s state), which will be installed at the current position of the detector (i.e. \unit[45]{cm} away from the EFI) in the full spectroscopy setup.

 This is the first evaluation of the quantum state distribution in an antihydrogen beam, in a low magnetic field region and down to quantum numbers as low as $n = 15$. The $n$-distri\-bution of high Rydberg states was measured earlier at the AD~\cite{Pohl_2006} but in the presence of a strong $B$-field of 5.4~T where additional complications in the interpretation of the data arise \cite{Driscoll_2004,Vrinceanu_2004,Pohl_2006}.

The results presented here highlight the required steps towards antiatomic beam spectros\-copy, namely increasing the production rate and the population of the lower quantum states.
Estimates on the required production rate necessary to reach the goal of one ppm precision on the ground state hyperfine transition frequency can be made by using our results on hydrogen~\cite{Diermaier2017aa}, which indicate the need of $\approx 8000$ $\overline{\mathrm{H}}$ for one measurement.
Therefore, the rate of $\overline{\mathrm{H}}$ atoms in the lowest quantum states needs to be increased by one to two orders of magnitude.
Hence current efforts focus on investigating methods to boost the production rate, e.g. by decreasing the positron temperature \cite{Radics2014} and also pursuing deexcitation techniques like collisional deexcitation in plasmas \cite{Radics:2016} and light-stimulated deexcitation \cite{wolz:2019} to increase the number of $\overline{\mathrm{H}}$ atoms in the ground state that reach the cavity.

\section*{Acknowledgements}
The authors are grateful to Eric Hunter for pointing out that the classical model for field ionization used in our previous work is not valid and for his initial inputs to the proper treatment, and for useful discussions with D. Comparat on the field ionisation of hydrogen.
We also express our gra\-titude towards the AD group of CERN. This work was supported by the European Research Council under European Union's Seventh Framework Programme (FP7/2007-2013) /ERC Grant Agreement (291242), the Austrian Ministry of Science and Research, Austrian Science Fund (FWF): W1252-N27, the Grant-in-Aid for Specially Promoted Research 24000008 of Japa\-nese MEXT, Special Research Projects for Basic Science of RIKEN, Universit\`a di Brescia and Istituto Nazionale di Fisica Nucleare and the European Union's Horizon 2020 research and innovation programme under the Marie Sk\l{}odowska-Curie grant agreement No 721559.

\section*{Author contribution statement}
M.T., N.K., H.H., Y.N., and Y.K. developed and operated the MUSASHI trap and provided ultraslow antiprotons. M.T., N.K., H.H., Y.N., and Y.K. developed and operated the double Cusp trap and provided antihydrogen atoms. D.J.M. designed, constructed, and developed the positron trap, which was operated by P.D., Y.K., H.H., M.T., and N.K. B.R developed the ASACUSA Micromegas Tracking detector and reconstruction code from which V.Mae and B.R. analyzed the data. M.L., V.Mas., and L.V. contributed to develop the pion-tracking detector, its data acquisition system and the off-line software for the data analysis of the tracking detector. Y.N., N.K., and M.T. developed the BGO annihilation detector.
C.M., C.S., B.K., A.C., M.F., J.Z., O.M., and E.W. conceived, built, and tested the hodoscope detector, C.M. and C.S. developed the trigger and data acquisition for the antihydrogen detector. M.C.S. and C.M. developed the External Field Ionizer.\par

The experiment was coordinated and predominantly operated by N.K., V.Mae., Y.Y., B.K., and M.F.
In addition M.T., N.K., Y.N., P.D., H.H., Y.Mas., V.Mae., B.K., C.S., M.F., O.M., M.W., S.A.C, and H.B. were involved in the data taking campaign. B.K. performed the\\ machine-learning based data analysis. C.M. and M.C.S. took part in critical discussions of the procedure. B.K. wrote the manuscript (section 5 was drafted by C.M.), which was edited by C.A., together with C.M., M.C.S., D.J.M., E.W., and N.K. The study of the ionisation of Stark states has been carried out by T. W. and C. M, with input from M.C.S. and D.J.M.\par

Y.Y. and partly N.K. participated in the basic design and construction of the cusp system including the Cusp trap and the MUSASHI trap, Y.Y. and N.K. conceived and proposed the Cusp trap for making antihydrogen beam for the ground-state hyperfine splitting measurement, E.W. proposed the method for the ground-state hyperfine splitting measurement with antihydrogen.\par

All authors critically reviewed and approved of the final version of the manuscript.

 \bibliographystyle{epj}


text:
Doing Things with Novels
course site for ENGL 720, Textual Studies in the Digital Age, Fall 2020
etexts
Bartleby, the Scrivener, a story of Wall-Street
Group Project #3: playing Larsen's work
Group Project #2: Benito Cereno and its intertexts
GROUP PROJECT #1: audiobook version of Bartleby (due 9/27 in class)
"yahoo" annotation assignment
James's audiobook reflection + Benjamin post
Posted on April 18, 2016 by Jeff Allred
[posted for James]
[reflection on audiobook]
Audiobook Reflection
The idea of a do-it-yourself audiobook struck me as very much within the scope of an English class seeking to both honor its roots in a certain literary tradition but to extrapolate vastly forward into the technological age we live in. I have perused LibriVox only a handful of times, once having downloaded a few dry works of Continental philosophy like some kind of self-help serum that goes down easier through the ears. However, my time with the works was fairly short lived, and I recall their quickly serving me more as a sleep aid than anything else. In my younger years, though, I once had a very positive experience with an audiobook in the car of an English teacher who took me on a summer camping trip—this one, as I recall, had a single narrator who very deftly took on voices of various characters, considerably unlike the tone of the narrator in the LibriVox work I encountered. Anchored in this positive memory, and also recalling the juvenile eagerness with which I always volunteered to read out loud in elementary school, I was pretty enthused at the idea of working on an audiobook.
Like many others in the class, I felt considerable alarm at the prospect of a group project. I scratch my head, but fail to recall the last instance in which it was necessary to collaborate with others on schoolwork. Like many others noted as well, I quickly became aghast with the sound of my voice—it is probably good that I waited till all my takes were done to listen back to any single one, because I fear that the anxiety induced by a single listen would have tainted the quality of the work moving forward. Surely, this feeling is not unique. However, upon listening to the work of my group mates, I felt greater pleasure at the quality of their narration than of my own, and hoped perhaps someone in the group might have a parallel sentiment as a way of soothing myself.
The editing work was probably the most fun part of the entire process. I enjoyed the multitude of bodily sounds—gurgles, slurps, throat noises, phlegm—that had been afforded by the very sensitive iPhone microphones we opted to use. Luckily, cleaning these kinds of things up was fairly simple—in a digital rendering of the sound files, little bumps in the wavelength corresponded to these minor disturbances and a quick scan made it easy to locate and eradicate the unwanted byproducts. I contemplated amplifying them and embracing the absurd humor of such an act, but I figured the rest of the class might not find it as funny as I do. After several rounds of cleaning, I proceeded to check that each portion of audio ran comfortably (meaning, no awkward pauses within a single file, or uncomfortable gaps between portions of text, and smoothly running transitions between narrators), and lined everything up. Finally, I added a track by Nils Frahm to augment the emotional weight of Ezra's reading of the book's conclusion.
All in all, a fun attempt at a forward thinking exercise that hit mark in remediating a traditional text that benefited from its sonic treatment.
[post on Benjamin]
"This patient process of Nature… was once imitated by men. Miniatures, ivory carvings, elaborated to the point of greatest perfection, stones that are perfect in polish and engraving, lacquer work or paintings in which a series of thin, transparent layers are played one on top of the other—all these products of sustained, sacrificing effort are vanishing, and the time is past in which time did not matter. Modern man no longer works at what cannot be abbreviated."
In his discussion of oratory tradition, Benjamin makes this note about a fundamental way in which temporality and artistic process has changed. I can only take guesses as to what has contracted modern man's patience, but my best guess will be something about a shift in the mode of production, and one's relationship to land.
Benjamin's notion of the storyteller is bimodal, being the combination of the land-bound artisan who stays permanently in place (on the land: fixed spatially but thus hyperaware temporally) and the sea-farer who brings with him stories of far-away (here, the temporal dimension is somewhat suspended but the spatial changes are what engender the storytelling). But the scale of time they are working with seems to be pre-modern, or of antiquity. Just as a craftsman prior to industrial-mechanized-automated labor worked as a lifelong process of improvement, the oratorical traditional was like, as Benjamin figuratively describes, many thin transparent layers of lacquer culminating in an organic enrichment of the story. Works handed down over generations (religious texts strikes me as a good example) seem to engage a passing of time that feels supernatural in scope—in the Biblical voice, the feeling of time is somewhat timeless, a procession of events that cannot be pinned to any temporal marker comfortable to our modern minds. The works handed down over the years exist in relationship to their setting, where the craftsman has been fixed, subsisting from the Land to whom these stories belong.
When Benjamin notes that "modern man no longer works at what cannot be abbreviated", it feels like a jibe, and disingenuous dismissal of modernity (even he, later in this essay, seems to concede that literary time enables, like a Futurist or Cubist artwork, the colliding of multiple time-perspectives). The relationship to the land (or at least the immediacy of that feeling) seems to be lost; humans no longer think or feel out in the world—perhaps labor alienation has caused them to withdraw deeper into their own psyche, where I feel the realm of the novel is situated. And a more inner, psychological assessment of time feels timeless (not in that monumental Biblical sense mentioned earlier), all senses and scales of time compounded and folded into a single point of access within one's mind, from which one can travel back, forth, and dilate at will. I would argue that perhaps it is not that modern man fails to have patience at anything that can't be truncated (though I would argue that perhaps over time, our attention spans have narrowed—and this discussion is more than pertinent to Digital Humanities if it seeks to grapple more with our relationship to technology), but rather that modern man no longer sees the need to conceive themselves in sweeping arches of time that emanate from Earthly posterity. In conceding to the thought of Lukacs and his idea of "transcendental homelessness", it feels that Benjamin does certainly grasp this symptom of modern man and thus the novel, in which "the meaning of life", and its unity, can be "compressed in memory".
Blog Post #5: Reflection on Mantrap
[I know I'm late posting this, so your response will not be due until Monday at 5pm!]
To focus your reflection on our gameplay of Billy Budd, I would like you to write a post of the usual length that reckons with the following three questions (you can either write three responses or weave the three questions into a single mini-essay):
How did your reading of the text change by virtue of looking at it through a single "window"** (i.e., the POV of your character or persona)? What did you learn about the novel by playing this role rather than simply reading the text?
What are the pleasures and frustrations of "playing" a novel, rather than reading it? What obstacles did you encounter, and how did you deal with them?
If you were to play again, what would you do differently? Would you pick another role? What moves would you change? What different moves might you make?
**Henry James famous likened the novel genre to a "house of fiction" that "has in short not one window, but a million — a number of possible windows not to be reckoned, rather; every one of which has been pierced, or is still pierceable, in its vast front, by the need of the individual vision and by the pressure of the individual will."
Posted in Assignments	| Tagged BILLY BUDD, ivanhoe	| Leave a reply
Rubery online lecture on audio books next week (9/17)
Julia's Genius Project
Jenna + Lauren's final project
Final Thoughts on Ivanhoe & Gaming Readings
Classroom collaboration etiquette
Ideas for the last week of class | LitHub@Hunter on final "presentation" guidelines
Jeff Allred on Genius Annotation Project Proposal
Jeff Allred on Final Project Proposal: Story Map The Mars Room by Rachel Kushner
Jeff Allred on Digital Mapping of Oral Histories
Jeff Allred on "Something is rotten in the state of Denmark."
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redpajama_set_name: RedPajamaCommonCrawl


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Everything You Need To Know About a Motorhome Holiday in WA
by Jairish Tadeo | Mar 15, 2016 | Destinations, Self Drives | 0 comments
If you only have been to Australia's East Coast, you are missing half the fun of your visit in this awesome country. So, this year, go instead to the lands of arid outback and magnificent sunsets: Western Australia (WA).
With a land area of 2.646 million square kilometres, Western Australia is recognised as the second largest state in the world. How big is that? About half the size of Europe. Getting around this state is challenging, even if you have your own vehicle. To help you plan your motorhome holiday in WA, we've put together a few tips for y0u.
Going North or South
Exploring the entire WA landscape will take you months. If you only have a few days or a week of vacation the best option is to choose whether to go north (Monkey Mia, Exmouth, Shark Bay, etc.) or south (Albany, Margaret River, Esperance, etc.).
Perth is the usual starting point of motorhome or campervan renters, because of the city's many attractions and accessibility to more remote tourist areas. Visit great spots in the city like the underground tunnels of Fremantle Prison, the 82.5-metre Bell Tower, and the relaxing Rottnest Island.
Once you have chosen which direction to go, plan your trip carefully by visiting tourist spots that are near each other. For example, you can do The Indian Ocean Drive, by travelling from Perth to the Abrolhos Islands, and back in four days.
BY Amanda Slater
When is the Best Time to Visit WA?
Western Australia has three climate zones: Perth, South West and Margaret River, and North West and Broome. The state has a generally sunny climate with an average of 3,000 hours of blue sky a year. From the south's Mediterranean climate, the east's desert-like environment and the north's tropics- WA is renowned as a year-round holiday mecca.
Perth is bathed in sunshine nine hours a day, making it the sunniest capital city in Oz. Average summer temperature is 29 °C, but can climb up to more than 40 °C in February. Winter temperature averages 12 °C on the months of June to August.
The south-west region has a Mediterranean climate which contributed to the biodiversity of the region. Margaret River's mild weather has made it one of the best surfing capitals and a distinguished wine region. The best time to visit the beach is in December when the temperature is between 25 and 35 °C.
Broome and Kimberley are top spots for winter sunshine. Temperatures during April to September dry season peaks at only 29 °C. Green season in the region (October to March) are very humid and brings tropical rainstorms.
Getting a Good Motorhome
Motorhomes and campervans are the most convenient way for non-locals to go around Western Australia. You can easily book a vehicle online and pick it up in the rental company's branch. In WA, it is likely in Perth.
When you walk in to get your vehicle, check if it has an up-to-date log of mechanical work to ensure that it is in good condition. Don't accept a unit that has maintenance and repairs carried out without receipts or records. Examine the most crucial parts of the motorhome as they are often subject to damage. These are the engine, brakes, gears, steering wheel, instrument panel, windscreen and coolants.
Motorhome Fine Prints
Advise your motorhome or campervan hire company of your itinerary in WA. Some may not allow you to travel on off-road tracks and non-national highways. Check their terms and conditions first before booking a vehicle.
Driving Around West Australia
Limit your driving mileage to 400-kilometres and take a break every few hours. Stop driving before 4 P.M. if you want to take an uninterrupted view of WA's magnificent sunset.
Set-up your campsite two hours before dark. For foreigners, Australia's vehicles are left-hand drives. If you are from a country that has right-hand drive cars get yourself familiar first with the vehicle you rented before driving long stretches.
Fuel Price Range
The price of oil is down for quite a while. Here are the latest fuel prices around Western Australia:
Town or City Price of Petrol per Litre Price of Diesel per Litre
Albany $1.24 to $1.26 $1.21 to $1.24
Bunbury $1.20 to $1.23 $1.13 to $1.16
Kalgoorlie $1.32 to $1.35 $1.30 to $1.32
Mandurah $1.17 to $1.18 $1.18 to $1.19
Rockingham $0.99 to $1.0 $1.15 to $1.18
Perth $1.15 to $1.20 $1.24 to $1.26
**Based on WAFuelFinder.com fuel price tool (February 10, 2016)
Research the available campervan parks on your planned route and mark them on the map. Some campervan parks allow online booking, but others implement a first come first serve policy. On average you will spend $35 to $60 a day for unpowered sites and $75 to $ 120 per night for powered sites, depending on the park's location, season and the number of people in your group.
You can also ask the locals or other travellers if there are cheap caravan parks or free camping sites in the area you are currently in. See locations of caravan parks in Western Australia.
BY studio tdes
Cutting your Expenses
More features and equipment for your motorhome means more expenses. To cut down on spending, choose a unit depending on your priorities. For example, you can replace a $20 solar shower bag for a built-in shower. If you need entertainment during the trip, instead of a DVD player or TV, go for books, a music player, a deck of cards or even a guitar.
If you don't want to re-charge your motorhome hire in a park, carry your own solar panel which will allow you to charge your gadgets without stopping in any city and paying for more fees.
This pretty much sums up the things you need to know about a motorhome holiday in Western Australia. Make sure you do your research before coming to this vast tourist hub. For more travel tips and other resources, keep on reading Cheapa Campa blog.
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Cheapa Campa is an affiliated company of the Apollo Motorhome Holidays Pty Ltd.
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Nick Hodgson
< Back to Our People
What's great about Foundation Derbyshire?
It is the only Derbyshire charity that supports all sorts of different local groups and organisations tackling individual and community needs across the county. It is also very nimble on its feet in responding very quickly to emergencies such as the recent floods and the Covid pandemic. Underpinning all this is its effectiveness and efficiency in getting financial support out to exactly where it is needed.
Why do you like being a Trustee of Foundation Derbyshire?
I was born and bred in Derbyshire and spent all my working life at Derbyshire County Council. The county is very much home to my family. We owe it a great deal and I hope that by supporting the Foundation I can put a bit back to help other people and to say thank you.
I was born in Sheffield but have lived all my life in Derbyshire. Educated in Dronfield and then at Manchester University I started work as a Town Planner and eventually became Chief Executive of Derbyshire County Council before retiring in 2013.
Outside of work my two key achievements are helping Chris my wife to bring up our four kids in a happy family and growing the family holiday cottage business.


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Samantha Morton and Dominic West Board 'John Carter of Mars'
Samantha Morton and Dominic West Board John Carter of Mars
Evan Jacobs
— August 24th, 2009
In a story from The Hollywood Reporter actors Samantha Morton, Dominic West and Polly Walker are boarding John Carter of Mars for Disney. It based on a book series from Edgar Rice Burroughs. Andrew Stanton is directing.
Taylor Kitsch, Lynn Collins and Willem Dafoe are already part of this project. It follows a Civil War veteran (Kitsch) who gets transported to Mars. While there, he gets caught up in a war between the people of that planet.
Morton will play the role of Sola. She is the daughter of Dafoe's Tars Tarkas.
West will play Sab Than. He is prince of the Zodangans and he believes he is entitled to rule Mars. Lastly, Walker plays the role of Sarkoja. She is domineering Thark.
The screenplay was written by Stanton and Mark Andrews. The plan is for John Carter of Mars to go into production in early 2010.
Longtime Movieweb contributor that was uploading 1-minute movie reviews to the world wide web via AOL before Youtube or social media existed. I make tons of straight-to-video movies you can find at Amazon & Vimeo. DVDs are back!


The Estate Vault, Inc., the company providing electronic data managements services for organization, storage and protection of financial, personal, legal and medical information, announced that it has become partners with the British Virgin Islands-incorporated company International Medical Funds Trust (IMFT), and its New Zealand-based trustee company IMF Trustees Limited.
The purpose of the agreement between the companies is to deliver a suite of secure and interactive personal data management tools focused on helping patients and clients to have higher level of control over their personal information, while travelling out of their own country for medical procedures.
CEO of the Estate Vault also added that IMFT and Estate Vault have, in principal, agreed to establish an International Business Company (IBC) in the British Virgin Islands, which will become the provider of the range of converged hybrid products. This BVI IBC will be established under the Estate Vault International brand name.
The joint committee of ministries of the Chinese Government named Origin Agritech Limited for National Agricultural Industrialization -'Leading Enterprise'. Being awarded with this title, which is valid for a year, until July 2012, the BVI company will benefit from corporation taxation exemption, preferential purchase rights and other preferential policies.
The qualification of the company was approved by the following institutions: the Ministry of Agriculture, National Development and Reform Commission, Ministry of Finance, Ministry of Commerce, People's Bank of China, State Administration of Taxation, China Securities Regulatory Commission, and the China Federation of Supply and Marketing Cooperative.
Marubeni Corporation has entered into a Strategic Cooperation Agreement with a British Virgin Islands-registered company Winsway Coking Coal Holdings Limited. Winsway is one of the leading Chinese suppliers of imported high-quality coking coal.
Through this deal, the parties have agreed to expand coal sales to the Chinese market through Winsway. The aim of the companies is to achieve sales of over 2 million tons per annum of coking coal from Australia, Canada and other countries.
Winsway was the largest offtaker of Mongolian coking coal in 2009, so by cooperation with the BVI company Marubeni will be able to handle Chinese and Mongolian coal and provide a stable coal supply to Japanese and other markets.
The agreement includes provision for joint coal resource development by both companies, as well as possible consideration by Marubeni to become a shareholder in Winsway.
Winsway Coking Coal Holdings Limited was established in 2007 in the British Virgin Islands, its main business is distribution and transportation of coal from Mongolia and other countries into China.
BVI-registered Pansoft Company Limited announced that it has signed a contract with PetroChina Company Limited, the largest oil and gas producer and distributor in China. The contract for developing and installing treasury management system is approximately US$1.76 million worth, and the project is to be completed in three years.
The treasury management system for PetroChina will also incorporate thousands of its subsidiaries and will enable the management of all its resources under one common platform, representing one of the largest treasury management systems in China. It is to control the entire process of dynamic management and monitoring and controlling business flow, capital flow and integrated information flow.
This is not the beginning of BVI company's partnership with PetroChina. In the end of 2009, Pansoft signed contract for software system development with Chinese oil and gas producer. This contract, worth approximately US$5 million, was the largest for the BVI company.
You are currently browsing the BVI Company News blog archives for July, 2010.


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Il torrente Sansobbia (Sensòggia in ligure) è un corso d'acqua della provincia di Savona lungo circa 23 km.

Caratteristiche
Nasce dal monte Beigua a circa mille metri di quota in prossimità della Croce Monumentale che si trova a ponente della vetta. Oggi di dimensioni più modeste di un tempo a causa della riduzione delle piogge e del prelevamento idrico per agricoltura e acquedotti, il Sansobbia si sviluppa nei territori di Stella e Albisola Superiore della quale, nell'ultimo tratto sino alla foce, segna il confine da Albissola Marina.

A causa del suo regime torrentizio e non avendo approvvigionamenti idrici consistenti garantiti da ricche sorgenti o ghiacciai, per molti mesi all'anno, soprattutto in estate, non riesce a raggiungere il mare e le sue acque si perdono tra la sabbia del letto a tre o quattro chilometri dalla foce. Viceversa, in occasione di forti piogge, può rivelarsi molto pericoloso straripando o causando danni gravi alle aree limitrofe. L'ultima disastrosa alluvione vi fu nel 1992 con l'allagamento di Albisola, di parte dell'abitato di Èllera con frane e smottamenti consistenti nel territorio di Stella, dove diversi tratti della provinciale di collegamento con Ellera furono letteralmente spazzati via dall'acqua.

Il Sansobbia presenta il primo tratto del suo percorso all'incirca parallelo alla costa ligure per poi piegare quasi ad angolo retto da Santa Giustina fino a San Giovanni, dove procede verso ponente in direzione di Èllera. La discesa fino a Santa Giustina è caratterizzata da una forte pendenza e profondi canaloni scavati nella roccia durante gli anni. Dopo l'abitato di Santa Giustina la pendenza si fa più dolce, pur rimanendo profondamente incuneato tra le rocce come in prossimità del ponte della provinciale di San Bernardo (SP32). Giunto nei pressi di San Giovanni, il letto si allarga, lasciando spazio ad una ampia ansa verde, fertile e coltivata. Poi il Sansobbia riprende il suo corso tra le ripide colline fino a Èllera, costeggiandone la strada di collegamento con Stella (SP2) dalla quale è scavalcato da tre ponti. Dopodiché serpeggia stancamente in ampie anse sabbiose fino alla frazione di Luceto e da qui in modo quasi rettilineo fino al mare.

Un tempo molti erano i mulini che traevano energia dal suo corso. Alcuni sono ancora visibili, anche se non più funzionanti, come quello di Èllera che si trova subito al di là del ponte in pietra che collega l'abitato alla chiesa parrocchiale. Il letto del Sansobbia ha inoltre rappresentato per anni l'unica via di collegamento tra questa borgata e Albisola, prima della costruzione della strada attuale, realizzata negli anni trenta.

Laghi

Il Sansobbia non ha dei veri e propri laghi, considerate le sue dimensioni abbastanza ridotte. Poco sopra la frazione di Santa Giustina ci sono alcuni specchi d'acqua profondi un paio di metri chiamati laghetti, formati da sbarramenti naturali o artificiali (il maggiore è detto Lago del Gotto).
Nel tratto compreso tra il ponte di Corona e San Giovanni, esistono alcune ampie anse profonde anche tre metri, le cui due principali sono chiamate lago della Béra e lago Scuro.

Affluenti
Il principale affluente del Sansobbia è il Riobasco che nasce nel territorio di Stella e si getta nella sponda sinistra del Sansobbia ad Albisola Superiore.
Gli altri affluenti, partendo dalla sorgente, sono (S = sinistra; D = destra):
Rio Lampu (D), Rio Fossa (S), Rio Paanè (D), Rio Crivezzo (D), Rio Mazzona (S), Rio Caeffu (S), Rio Luqui (D), Rio Rossella (D), Rio Cria (D), Rio Crovaro (D), Rio Magrania (S), Rio Burage (S) e Rio Grana (D).

Note

Voci correlate
 Stella (Italia)
 Albisola Superiore
 Ellera (Albisola Superiore)
 Riobasco

Altri progetti

Sansobbia
Fiumi tributari del mar Ligure
Albisola Superiore

redpajama_set_name: RedPajamaWikipedia


As we shared on the Internet of Things Podcast, we now have a dedicated line for listeners to call in and leave a voicemail. In case you need the number, it's 512-623-7424; be sure to drop us a comment or question!
Instead of turning to Google Voice, Skype or some other readily available voicemail solution, we decided to take an IoT approach and build our own. It wasn't that difficult and I learned quite a bit from trying to put the pieces together.
We bought a Raspberry Pi 3 Model B with clear case and 2.5A power supply for $45 to host the service. Once that arrived, I attached the Pi to a monitor, keyboard and mouse that I already had. Using another computer, I downloaded the Raspian operating system to a microSD card which is need to boot up the Pi. You can purchase a bundle that includes a pre-loaded microSD card, but if you don't do that, the Pi won't boot, so you can't use it to get the operating system.
This Raspberry Pi model supports both wired and wireless networks, so upon the first boot up, I connected to my wireless home network without any problems. Python is pre-installed in the Raspbian build, so I didn't have to install that. Python is the scripting language I chose to use for the project, however, it can be done with alternatives as well.
Python alone isn't quite enough though. For phone calls, SMS and voicemail support you need additional tools. Enter Twilio.
Twilio is a low-cost cloud service that provides APIs that add communication services to applications. We bought our phone number, which costs $1.00 per month, even if we don't use for any calls or messages. Twilio charges $0.085 a minute for incoming calls and $0.013 a minute for outgoing calls. Sending or receiving a text message from our Twilio number costs $0.0075, while recording a voicemail is only $0.0025. Even if we receive 100 messages a month, the cost of those, plus the phone number, is only two or three dollars. To increase the security of this task, it might be a good idea to consider a proxy server from companies similar to fineproxy. The last thing you'd want is to get hacked! But I digress.
Before creating and running the Python app that powers the voicemail, the Twilio libraries need to be installed on the Pi through one of these three commands in the Terminal app. Additionally, the Flask micro web development framework needs to be installed in the Terminal. Flask sets up a light web server for the Twilio APIs to interact with while our Python scripts provide instructions for how to handle incoming calls.
Although I've spent some time tinkering with and learning Python over the last few months, I don't have much experience with building apps that call third-party APIs, such as those from Twilio. Luckily, Twilio offers several Quickstart examples for a number of programming languages. And one of those examples shows to how to create a Python app that accepts incoming calls, plays a voicemail greeting and records a caller message. This is the Quickstart code that I tweaked for our project.
Some of the Quickstart code wasn't necessary for our IoT Podcast voicemail. The first section of code highlighted in the above image, for example, is used to identify callers for a customized greeting, but only if you know the caller's number in advance. So I removed that. Additionally, there's a section of code that reads aloud text for the voicemail greeting. We decided to record our own MP3 file for the greeting, so I modified that line as well. You can tweak the sample code however you'd like if you decide to create a similar project.
With all of the libraries installed and the Python code modified, our app is ready to accept calls and record voicemails. But it can't quite do that just yet. There's one more step: Twilio actually needs to know where on the internet the Raspberry Pi is running. Since this is a local server, that's a bit tricky, but there's a simple solution called Ngrok.
According to its website, Ngrok is a way to "expose local servers behind NATs and firewalls to the public internet over secure tunnels" which is how we connect the Pi server to Twilio services in two steps after downloading and installing Ngrok on the Pi.
First, we run Ngrok with the following command in another Terminal instance: ./ngrok http 5000. Once Ngrok is running, the app provides a unique URL for our local web server, such as https://27195c65.ngrok.io. Now that we have a URL, we simply need to configure Twilio to use it. In the Twilio Console for our phone number there's a place to add the custom URL and then save the configuration.
Once Twilio and Ngrok are configured, it's time to launch the Python app in its directory with a simple command line in the Terminal: python vm.py. Now, when a call comes in, Twilio pings our web server which tells it what to do via the Python script.
We decided to beef up our system with a few extra features: server monitoring and voicemail notifications. Both of these were super easy to enable.
For monitoring the online status of the Raspberry Pi, I turned to Uptime Robot, which offers both free and paid plans. Since we're not an enterprise, the free plan is fine for our needs: Every five minutes, It pings the URL of the webserver on our Raspberry Pi. If there's a problem, Uptime Robot sends me an email to research the issue.
Note in the above screenshot, our system ran perfectly fine for nearly three weeks. On September 12, however, we must have lost internet connectivity in my house as shown by the 9 minutes of downtime. The Pi and our scripts were running fine, but the webserver didn't have web connection in the wee hours of the morning. Regardless, that problem thankfully sorted itself out!
Of course, we want to know as soon as an incoming voicemail is saved, so again, it's Twilio to the rescue. By adding a few lines of code to our Python script, Stacey and I each get an SMS notification telling us there's a new message.
Note that Twilio's API requires a separate call for each message to be sent, which is why the similar code repeats once for Stacey's phone number and then again for mine. If you plan to send bulk messages from Twilio, I expect that you can build a list of phone numbers and loop through them with the API call. Since we only have two contact numbers and don't expect to add any more, I decided not to loop through a list of two elements.
Once we're notified of a message, it's just a matter of logging in to Twilio and downloading the voicemail for an upcoming episode.
There you have it! With an inexpensive Raspberry Pi, a little coding knowledge and effort, Twilio's excellent APIs, documentation and Quickstart code, you can make your own voicemail server. For that matter, you can do a number of other things related to voice or message communications as well!
wow this is great stacey.. gonna put this in my python bucketist..
Glad you liked it Robert! I know everyone is used to Stacey writing everything on the site, so folks probably didn't even notice the byline. 😉 I'm going to be contributing more content here going forward, so stay tuned!
This is great! Do you have any issue with the ngrok URL changing each time you start up the ngrok tunnel?
Thanks David and great question. Yes, any time you have to start or re-start ngrok, a new URL is generated. It's not a major issue, but once you have that URL, you do have to go back into the Twilio Console and update the web hook URL. Takes a few seconds and is easy to do.
As far as GitHub, that's a good idea. But I think I'm going to pass on it (for now) mainly because the linked QuickStart page has all of the code to get a sample VM system running. In the post, I highlighted what code I removed and then added for the VM notification. Actually going through the QuickStart code step by step taught me a lot, so I recommend folks start there. Additionally, they'll need the code to reflect their own Twilio credentials and phones numbers. Thanks!
I'm going to add this to my future projects list. Thanks for the hard work.
Thanks Steve! Let us know how this works out if you implement a similar or related voice communications project.
Is there any limit to the length of the voicemail?
It looks like Twillio charges by the minute even though it appears that the voice file gets saved on the Pi.
I'd like to use this to record phone calls by patching it in like adding a third party using the three-way function on my cell phone.
There is a limit on the VM length but you can modify it. This line of the script has a maxLength parameter, represented in seconds: resp.record(maxLength="30″, action="/handle-recording"). If you changed that value from 30 to 120, for example, the max VM recording length would be 120 seconds, for example. Note that the voice mail recording is not stored on the Pi; it's stored on Twilio's servers, hence the per minute charge from Twilio for the recording and the service.


It was afros and James Brown, platform shoes and Parliament Funkadelic. It was the dawn of the '70s In Houston, Texas, where a full-fledged funk powerhouse would be born at a black high school called Kashmere. Conrad 'Prof' Johnson would turn his school's mediocre jazz band into an international phenomenon. And now, 30 years later, former band members dust off their instruments and prepare to pay tribute to the man who changed their lives long ago.


Offering a small incentive with a meal may motivate kids and adults to choose smaller portions, suggests a new study that found uncertain incentives stimulate the same reward centre of the brain as food.
Researchers from the University of Arizona and the University of Southern California in US have found that offering a small incentive with a meal consistently motivates kids and adults to choose smaller portions.
Not only can a small prize motivate the healthier meal choice, but the mere prospect of getting it is more motivating than the prize itself.
The researchers found that people were more likely to choose a smaller meal for the chance to win a USD 10 lottery than to get a guaranteed reward. The premiums in the study were the chance to win USD 10, USD 50 or USD 100.
"The fact that participants were willing to substitute part of a tangible food item for the mere prospect of a relatively small monetary premium is intriguing," said Martin Reimann from the University of Arizona.
While participants identified their choices with various foods and incentives, researchers collected neuroimaging data with fMRIs.
The results showed that the combination of half-sized portion and nonfood premium activates similar areas of the brain (specifically, the striatum which is associated with reward, desire and motivation) as the full-sized portion alone.
People were strongly motivated to choose half a burger or pizza even if they were hungry, and they did not compensate by eating more calories later.
Desirability of the prize also impacts motivation, the researchers found. While uncertain prizes are highly motivating, further research showed that a vague possibility of winning frequent flyer miles was more effective than a probable contest that listed the odds.
"One explanation for this finding is that possible premiums may be more emotionally evocative than certainty premiums," Reimann said.
The findings imply that individuals can reward themselves for eating less food with nonfood items, researchers said.


EnOcean Link is EnOcean's middleware for energy harvesting wireless technology. OEMs can integrate EnOcean technology easier and faster into a wide range of applications and systems, such as those in smart homes. The software provides a universal interface for EnOcean wireless protocols and automatically interprets information from EnOcean devices. As a result, sensor data such as moisture or temperature is prepared so that different devices, servers and even cloud services can process it immediately. OEMs can obtain EnOcean Link directly from EnOcean as licensed software.
When you are interested in the Trial Version please log in (bar above) or register and download option will show. The trial version is for free so you can evaluate the most important functions of EnOcean Link. For final products use the Full Version.
When you are interested in the Full Version please contact us under info-delete this text-@-delete this text-enocean.com or see the sales contact.


We offer 14 large, short term pull-through sites and 63 back-in sites with their own grassy areas and flowering plum trees. For your camping pleasure, each site offers lighted power pedestals with easy water and sewer hookups.
Our guest facilities include restrooms, showers, laundry, meeting/TV room with soda and snack machines. Handicapped accessible. Security cameras for guest safety are monitored 24 hours a day.


text:
New Issues in the Management of Patients With AIDS-Related Cytomegalovirus Retinitis
Gary N. Holland, MD
Arch Ophthalmol. 2000;118(5):704-706. doi:10.1001/archopht.118.5.704
Discontinuation of Anticytomegalovirus Therapy in Patients With HIV Infection and Cytomegalovirus Retinitis
Scott M. Whitcup, MD; Eric Fortin, MD; Anne S. Lindblad, PhD; Paul Griffiths, MD; Julia A. Metcalf, BA; Michael R. Robinson, MD; Jody Manischewitz, MS; Barbara Baird, RN; Cheryl Perry, RN; I. Michael Kidd, PhD; Tamara Vrabec, MD; Richard T. Davey, Jr, MD; Judith Falloon, MD; Robert E. Walker, MD; Joseph A. Kovacs, MD; H. Clifford Lane, MD; Robert B. Nussenblatt, MD; Janine Smith, MD; Henry Masur, MD; Michael A. Polis, MD
Context Persons with cytomegalovirus (CMV) retinitis and acquired immunodeficiency syndrome (AIDS) have required lifelong anti-CMV therapy to prevent the progression of retinal disease and subsequent loss of vision.
Objective To determine whether patients who were taking highly active antiretroviral therapy (HAART) and who had stable CMV retinitis could safely discontinue anti-CMV therapy without reactivation of their retinitis or increase in human immunodeficiency virus (HIV) viral load.
Design Prospective nonrandomized interventional trial performed from July 1997 to August 1999.
Setting Clinical Center of the National Institutes of Health, Bethesda, Md.
Patients Fourteen patients with stable CMV retinitis and HIV infection and CD4+ cell counts higher than 0.15 × 109/L and being treated with systemic anti-CMV medications and HAART.
Interventions Discontinuation of specific anti-CMV therapy.
Main Outcome Measures Reactivation of CMV retinitis, development of extraocular CMV infection, detection of CMV in blood and urine, HIV burden, immunologic function, quality of life, morbidity, and mortality.
Results Twelve (89.7%) of 14 patients had evidence of immune recovery uveitis before anti-CMV drugs were discontinued. No patient had reactivation of CMV retinitis or development of extraocular CMV disease during mean follow-up of 16.4 months (range, 8.3-22.0 months) without anti-CMV therapy. Human immunodeficiency viral load remained stable following cessation of anti-CMV medications. Blood and urine assays for CMV were briefly positive in 9 patients but did not predict reactivation of CMV disease. Worsening immune recovery uveitis was associated with a substantial (>3 lines) vision loss in 3 patients.
Conclusions Maintenance anti-CMV medications were safely stopped in those patients who had stable CMV retinitis and elevated CD4+ cell counts and who were taking HAART. The study demonstrates that immune recovery following potent antiretroviral therapy is effective in controlling a major opportunistic infection, even in patients with a history of severe immunosuppression.
1999;282:1633-1637.
Cytomegalovirus Retinitis in the Era of Highly Active Antiretroviral Therapy
Scott M. Whitcup, MD
A number of striking changes have occurred recently in the presentation and course of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS) who are receiving highly active antiretroviral therapy (HAART). Before the use of HAART, CMV retinitis was the most common intraocular infection in patients with AIDS, occurring in up to 40% of patients, typically when CD4+ cell counts have decreased to less than 0.10 × 109/L. By studying CMV retinitis, clinicians can investigate whether the rejuvenated immune system that results from HAART can effectively control opportunistic infections in patients with AIDS. In some patients, retinitis has not progressed when specific anti-CMV therapy was discontinued, but a number of patients have developed substantial intraocular inflammation, which has resulted in decreased visual acuity. Anterior uveitis, cataract, vitreitis, cystoid macular edema, epiretinal membrane, and disc edema may occur in patients with CMV retinitis who have experienced HAART-associated elevation in CD4+ cell counts. Since immune recovery uveitis does not occur in eyes without CMV retinitis, the ocular inflammation appears to be related to the CMV infection. Anti-CMV maintenance therapy likely can be safely discontinued in some patients with CMV retinitis if CD4+ cell counts are stable or increasing and have been higher than 0.10 × 109/L for at least 3 months. Immune recovery in patients receiving HAART has been effective in controlling opportunistic infections, but it may also result in intraocular inflammation, which can have adverse effects on the eye.2000;283():653-657.
Allergy and Clinical Immunology HIV Infectious Diseases Intraocular Inflammation Ophthalmology Retinal Disorders
Holland GN. New Issues in the Management of Patients With AIDS-Related Cytomegalovirus Retinitis. Arch Ophthalmol. 2000;118(5):704–706. doi:10.1001/archopht.118.5.704


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