text:
\section{Introduction}

PF1B is a user facility at the Institut Max von Laue - Paul Langevin (ILL) in Grenoble, France, for experiments in elementary particle and nuclear physics using polarized or non-polarized cold neutrons. PF1B is located at the end position of the ``ballistic'' $m=2$ super-mirror cold neutron guide H113 with an exit cross section of $60\times 200~mm^2$ ~\cite{Abe2006nima} (note that the capture flux at the guide exit of $1.35\times 10^{10}~n/cm^2/s$ reported in~\cite{Abe2006nima} has been improved to $2.2\times 10^{10}~n/cm^2/s$ at nominal reactor power by replacing guide sections that had suffered radiation damage and by upgrading the in-pile part).

An important component of PF1B is a cold neutron polarizer that has to produce a large-area, $\sim 80\times 80~mm^2$, well-polarized neutron beam over an extended range of neutron wavelengths, $0.3-2.0~nm$. For the needs of experiments of different types, PF1B has to provide several options of optimization including a maximum total flux of polarized neutrons over a large beam cross section, a maximum flux density of polarized neutrons over a relatively small beam cross section, and ultra-high precision of the knowledge of the polarized neutron beam properties. While in the first two cases, the average polarization can be moderate (typically $P_n > 0.98$), the latter option requires ultra-high polarization ($P_n \geq 0.997$) to minimize systematic uncertainties ~\cite{Ves2008prc,Gle2017plb,Goe2007plb,Gag2016prc,Mar2019prl,Kre2005plb}.

In order to achieve high polarization levels with reasonable transmission over the full wavelength range, the preferred technology is typically super-mirror (SM) benders ~\cite{Mez1977cp,Dra1977jtp,Sch1989pb,Maj1995pb,Mar2007tsf,Kri2008,Mez1989spie}. Ultra-high polarization is difficult to achieve with single reflection or transmission by a polarizing SM, though noticeable investigation was made in that direction \cite{Ple2010nima}. Therefore, the design of the polarizer geometry aims at making most neutrons reflect at least twice on polarizing SMs, with sufficiently large angle of incidence, when going through the device \cite{Kre2005nima,Pet2016nima}.

The previous PF1B polarizer was built using the traditional technology of air-gaped reflection-type polarizing benders. It consisted of $30$ channels of $80~cm$ length and $2~mm$ width. The thickness of the borofloat glass substrates was $0.7~mm$. The Co/Ti/Gd SM coatings ~\cite{Sch1989pb,Els1994tsf,Cou2013ILL} had the effective critical velocity of $m=2.8$. The polarizer cross section was $80\times 80~mm^2$, the radius $300~m$, and the applied magnetic field $120~mT$ ~\cite{Sol2002ILL}. This polarizer was produced in collaboration between the ILL (SM coatings) and the TU M{\"u}nchen (glass and assembly). It was installed in 2002 downstream the H113 guide in an effective neutron capture flux of $\sim 2\times 10^{10}~n/cm^2/s$. The measured transmission was $\sim 0.49$ for the ``good'' polarization component. The capture-flux-averaged polarization was $P_n\sim 0.985$.

When ultra-high polarization was required, we installed a second polarizer of the same type in the ``X-SM geometry'', thus providing a mean polarization of $P_n =0.997$ and a transmission of $\sim 0.25$ for the ``good'' polarization component ~\cite{Kre2005nima}. This geometry assumes that the reflecting planes in the second polarizer are orthogonal to the reflecting planes in the first one.

However, during more than 15 years of successful exploitation, this polarizer was irradiated with a very high neutron fluence which resulted in a significant irradiation damage to the mirrors' borofloat glass substrates, mainly by the charged particles from the reaction $^{10}B(n,\alpha)$ in the glass substrate. It is also strongly activated, mainly due to the presence of Co in the SM coatings, which makes its handling seriously complicated.

In this paper, we present the new, Advanced polarizer built for the PF1B instrument at ILL with improved polarization and free from the radiation damage and activation issues. The polarizer design, the choice of substrate and SM coating, and the magnetic housing are described in great details in our previous publications ~\cite{Pet2016nima,Pet2019rsi}. Here, we focus on the full scale polarizer production and the results of measurements of its characteristics.

\section{\label{sec:Design}Polarizer design}

To avoid some drawbacks of the previous polarizer, namely the high activation of Co in the Co/Ti SM coatings and the neutron-induced degradation associated with the $^{10}B(n,\alpha)$ reaction in the borofloat glass substrates, we decided to build a solid-state polarizer with Fe/Si coatings ~\cite{Maj1995pb,Kri1998pb,Hog1999pb,Stu2006pb,Big2009ILL,Wil2011itr}.

An immediate advantage of the solid-state polarizer is its compactness. It has a more favorable ratio of channel to inter-channel width and allows to design a magnetic system with better performance.

In traditional C-benders, a solid-state polarizer is built of a bent stack of thin ($150-200~\mu m$) single crystal Si wafers, coated on both sides with Fe/Si SM coatings terminated by Gd absorbing layers. Each Si plate coated with two reflecting SMs is a spin-dependent guide for neutrons which enter the plate bulk through the entrance edge of the plate. To avoid the direct view (i.e.\ neutron trajectories which do not touch the polarizing coatings) the bending angle $\gamma_C$ should meet the following condition:

\begin{equation}
\gamma_C\geq 8d/L,
\label{eq:gammac}
\end{equation}
where $d$ and $L$ are thickness and full length of the channel. A double-bent polarizer of this type is known as the S-bender~\cite{Stu2006pb,Big2009ILL,Wil2011itr}.

In our design of the new PF1B polarizer, we follow the concept proposed and described in detail in our previous publications~\cite{Pet2016nima,Pet2019rsi}. According to this ``advanced'' concept, we replace the single-crystal Si substrates by single-crystal sapphire. Since the neutron-optical potential for sapphire is higher than that for spin-down neutrons in the magnetized Fe of the SM coatings, this choice allows us to avoid the total reflection regime for neutrons of the unwanted spin direction propagating through the substrates. This modification expands the efficient polarizer bandwidth into the low $Q$ region.

The polarizer is built of two independent stacks of flat substrate plates of $80\times 25\times 0.18~mm^3$ (i.e.\ $L/2=25~mm$, $d=0.18~mm$), each coated with SMs on both sides. Each plate in the stack is mounted on the top of the previous one. The total number of plates in the stack is 440 thus providing the total polarizer cross section of $80\times 80~mm^2$.

The two stacks of mirrors are tilted by angle $\gamma_\nu$:
\begin{equation}
\gamma_\nu\geq 4d/L.
\label{eq:gammanu}
\end{equation}

We denote this type of polarizer the V-bender.

Fig.~\ref{fig:Vbender} illustrates the V-bender geometry in comparison with the traditional C-bender geometry.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig1.png}
\caption{\label{fig:Vbender} The V-bender geometry: two stacks of both-side SM-coated plane parallel substrate plates (with thickness $d$ and length $L/2$) are tilted by angle $\gamma_\nu$ with respect to each other. To avoid the ``direct view'', the angle has to meet condition Eq.~(\ref{eq:gammanu}). Note that the two halves of the V-bender do not need to be in contact, also the slits do not need to be lined up. The traditional C-bender geometry is indicated by dashed lines for comparison (the internal dashed lines are omitted for better readability).}
\end{figure}

An important feature of the V-bender is the absence of pronounced Bragg dips in the transmission for particular wavelength values. Such dips were observed in experiments with solid-state S- and C-benders when the angular divergence of the incident neutron beam is comparable to the bending angle~\cite{Stu2006pb,Sha2014nima}. For the reflection of neutrons from a flat perfect crystal, the acceptance angle of Bragg reflection is very small (typically $1-10~\mu rad$) and the corresponding dip would be completely washed out by the angular divergence of the incident beam (typically a few tens $mrad$) even in the case of an unfortunately chosen crystal orientation. Indeed, these expectations were confirmed in experiment as we observed no dip in the transmission.

As mentioned in ~\cite{Kat2018pcgcm,Pet2019rsi}, sapphire substrates are readily available ~\cite{Siegert} with sufficient polishing quality for SM coating and minimize the substrate bending due to the residual stress present in the coating. The latter is expected to be relevant when considering the geometrical imperfections of the final assembled mirror stack with respect to the ideal one. Together with the neutron optical properties, these features led us to choose sapphire as substrate material.

\section{Polarizing coating}

To explore the full angular divergence of the H113 ballistic $m=2$ SM guide and to cover the broad wavelength band of $0.3-2.0~nm$, we use the same ``inverse'' scheme $m=3.2$ Fe/SiNx SM coatings, consisting of 603 individual layers, which was previously used for the production of a solid-state S-bender~\cite{Stu2006pb,Big2009ILL}. The term ``inverse'' refers to the sequence order for the SM coating depositions, starting with a thicker layer as opposed to the sequence in SMs used for neutrons incident from air. Note that with such a sequence in a solid-state polarizer, the first layer visible to neutrons is the thickest one, as in the case of air-gaped devices.

An absorbing Gd layer also has to be coated on top of the SM so that neutrons which are transmitted through the SM do not get out of the polarizer or into the next plate. In order to guarantee that these neutrons are absorbed rather than reflected, even at low $Q$ values, an anti-reflecting and absorbing Si/Gd multilayer consisting of 41 individual layers and based on the same principle as in Ref.~\cite{Sch1994pb} was designed. The total thickness of Gd is larger than $500~nm$, assuring that the transmission of non-reflected neutrons through the interface between the plates stacked inside the polarizer is always well bellow $10^{-3}$ in the operation conditions.

The SM coating was produced in-house by reactive magnetron sputtering~\cite{Hog1999pb,Big2014jpcs}. Since the S-bender production~\cite{Stu2006pb,Big2009ILL}, some investigations were made about the magnetic properties of the coatings~\cite{Mar2016nima,Mar2019cry} and the neutron beam depolarization at reflection~\cite{Kla2013pp,Kla2016nima}. The coating process had been optimized further, resulting in magnetically softer multi-layers, i.e.\ requiring a weaker applied magnetic field to be magnetized close to saturation.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{FigurePlateau.png}
\caption{\label{fig:Plateau} Scheme of the deposition tray. The production version contains 48 sapphire plates of dimension $80\times25\times 0.18~mm^3$ each, a witness float glass sample and a witness thick sapphire plate with dimensions $80\times40\times 3~mm^3$ for neutron reflectometry measurements. These 2 additional substrates were placed in the free space (top-right corner). One thin sapphire substrate is highlighted in green, and the inset shows a detail of the triangular-shaped separator, used for masking the mirror edges without reducing the thickness deposited on their faces.}
\end{figure}

With our in-line sputtering machines, we used the tray shown in Fig.~\ref{fig:Plateau} to coat one face on a set of 48 sapphire substrates at once. In order to prevent coating the edges of the plates (where in particular Gd would reduce the neutron transmission significantly), special care was taken in designing the deposition tray, so that each mirror face is maximally coated without depositing material on the edges. In practice, an area of about $0.3~mm$ wide along the mirror edges was masked for this purpose. A witness float glass sample and a witness sapphire sample of $80\times40\times 3~mm^3$ were coated together with each set. All single-crystal sapphire substrates ($0.18~mm$ plates and $3~mm$ witness plates), with the c-plane parallel to the surface, were from ~\cite{Siegert}. For technical reasons, each coating was made in two steps with two different machines: one for the SM and one for the anti-reflecting absorbing multi-layer. The typical production cycle, for coating a set of 48 plates on both sides, was about one week. Twenty-five such cycles were achieved, spanning about six months, resulting in a total SM coated area of about $4~m^2$.

For each coating run, the witness float glass sample was removed from the tray after the SM coating, so that it can be measured by neutron reflectometry in the standard way, with neutrons coming from the ``air'' side. The witness sapphire samples of $3~mm$ thickness underwent both steps and were measured with neutrons entering by the substrate edge, reflecting at the SM from the substrate side. This allowed a systematic control of each coating performance in the same conditions as for the thin plates, which could not be measured by neutron reflectometry.

Fig.~\ref{fig:Reflectivity} shows typical spin-dependent reflectivity $R_{+},R_{-}$ measured with our test reflectometer T3 for one of the $3~mm$-thick sapphire witness samples. Most of the features, in particular the low-$Q$ part of the ``$R_{-}$'' curve, are consistent with the simulations presented in ~\cite{Pet2019rsi}. Through the whole production, the measured polarization after single reflection was $>0.985$ in the range $1<m<3$.

We also performed more accurate spin-dependent reflectometry measurements at SuperADAM~\cite{Dev2013rsi} equipped with an opaque polarized $^3$He analyzer. Fig.~\ref{fig:RvsQSAdam} shows the results of measurements for all 4 spin components $R_{++},R{+-}, R_{-+},R_{--}$.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{T3ReflectometryFleches2.png}
\caption{\label{fig:Reflectivity} Spin-dependent reflectivity ($R_{+}=R_{++}+R_{-+}$: red, $R_{-}=R_{--}+R_{+-}$: blue; left axis) measured with the T3 instrument on a $3~mm$ thick sapphire witness sample coated with Fe/SiNx/Gd SM and anti-reflecting absorbing layer in a production run. Neutrons with wavelength $0.75~nm$ entered by the substrate edge and were reflected at the SM from the sapphire side. The polarization (P: green; right axis) was calculated from $R_{+}$ and $R_{-}$, applying only a background correction.}
\end{figure}

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{RvsQSAdam.png}
\caption{\label{fig:RvsQSAdam} Spin-dependent reflectivity $R_{++},R_{+-},R_{-+},R_{--}$ measured at SuperADAM reflectometer with an opaque polarized $^3$He analyzer (the analyzing power of $>0.999$) and the applied magnetic field of $0.7~T$.}
\end{figure}

 Fig. ~\ref{fig:RvsQSAdam} shows that the beam polarization after single reflection ~\cite{Pet2019rsi} is $0.995<P<0.999$ in the same range $1<m<3$, i.e. it is significantly higher than the value $0.985$ measured at T3. We explain this difference by a lower polarization of the incident neutron beam and imperfections of the spin-flipper at T3 instrument.

For a polarizer based on multiple reflections, the resulting polarization is defined by the depolarization at the last reflection ~\cite{Pet2019rsi}. Therefore, we also measured at SuperADAM the spin-dependent reflectivity as a function of the applied magnetic field strength, see FIG. ~\ref{fig:RvsBSAdam}. In contrast to $R_{++}$ and $R_{--}$ that are field-independent for $B>10~mT$, the reflectivity $R_{+-}$ and $R_{-+}$ decays rapidly at the field strengths of up to $100~mT$, and continues decaying slowly at larger fields. This confirms the importance of a high magnetizing field and justifies our magnetic housing with $0.38~T$ permanent magnet ~\cite{Pet2019rsi} for the PF1B polarizer.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{RvsBSAdam.png}
\caption{\label{fig:RvsBSAdam} Spin-dependent reflectivity $R_{++},R_{+-},R_{-+},R_{--}$ versus the applied magnetic field measured at SuperADAM with an opaque polarized $^3$He analyzer (the analyzing power of $>0.999$). $m=1.92$.}
\end{figure}

\section{Assembling}

\subsection{\label{sec:Control precision}In-situ procedure to control the assembling precision}

In solid-state neutron polarizers, the plates with the polarizing mirrors are mounted on the top of each other thus forming a cassette which is needed in order to cover a significant cross section of the neutron beam. It is usually assumed that all plates are nearly identical and have a plane-parallel geometry.

Real plates can differ from plane-parallel as a result of the polishing process and due to residual stress in the coating. Imperfections of the geometry of individual plates as well as dust particles between them would result in a scatter of individual angles between the reflecting surfaces and the incident beam direction. The errors in setting the inclination angle would result in neutron reflection losses and an increased angular divergence of the reflected beam. The width of such dispersion increases with the number of plates in the cassette according to the law of ``Gaussian Random Walk'', see Appendix~\ref{app:RestrictionOnMirrorNumber}.

The primary effect of such an angular dispersion is the degradation of the polarizer transmission for the ``good'' spin component, provided that the width of the dispersion is comparable to the critical angle of the polarizer (typically $10-20~mrad$). This mechanism may explain the significant discrepancy between the expected and measured transmission often observed in experiments with solid-state neutron-optical devices ~\cite{Sha2014nima}. Some polarization loss may also be attributed to this effect since such an angular spread may make neutron trajectories without reflection possible.

The most straightforward way to minimize the losses of efficiency due to this mechanism would be to improve the precision in setting individual plates and to reduce the number of plates in the cassette. However, the number of plates in the cassette is fixed by the size of the required beam, and setting the inclination angle of individual plates with the precision much better than $\pm1~mrad$ is challenging.

An advantage of the rather simple V-bender geometry is the possibility to develop a procedure to actively control the inclination angle of each plate in the cassette, see Fig.~\ref{fig:Scheme}. The idea is to limit the cumulative effect of successive random plate misalignment, by making it ``less'' random through deterministic control and intervention on each plate. The stack of assembled plates is illuminated with a narrow laser beam (diameter $1~mm$), and the reflected beam is projected on a full-frame ($24\times 36~mm$) sensor of a digital photo-camera. Assuming $\boldsymbol{n}$ is normal to the top mirror of the reference plate and $\boldsymbol{n'}$ is normal to the top mirror of the inspected plate, which is inclined relative to $\boldsymbol{n}$ by a small angle $\delta$, the shift $\Delta$ of the spot position on the camera sensor is:
\begin{equation}
\Delta \approx 2\delta~h,
\label{eq:Delta}
\end{equation}
where $h\approx1000~mm$ is the distance between the plates and the sensor. We take the position of the reflected spot from the very first plate as the reference. If we observe that $\Delta$ is outside the accepted tolerance (typically $\pm~1~mrad$), we carefully inspect this plate and usually find a large dust particle. After removing it, the plate is assembled back to the cassette and we continue the procedure.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig3.png}
\caption{\label{fig:Scheme} Scheme of the in-house-built optical inclinometer: 1 - laser, 2 - plates in the stack, 3 - full-frame sensor of a digital photo-camera.}
\end{figure}

We found that at normal laboratory conditions, $\sim 0.25$ of the plates show an angular deviation $>1~mrad$. Therefore, we decided to perform all manipulations with the sapphire plates (before and after SM deposition) inside our class-100 laminar-flow box. This solution dramatically improved the output of ``good'' plates: practically all of them show a small spread of the inclination angle ($<1~mrad$). During the stacking procedure, when misalignment with the underlying plate of $>1~mrad$ occurs, there is still a possibility to flip the last plate upside down and check if the misalignment is reduced. In the rare case when this did not solve the problem, the last plate was replaced by another one.

To simplify the polarizer assembling we decided to use intermediate stacks composed of 25-30 plates. During assembling, the orientation of each plate is laser controlled according to the scheme shown in Fig.~\ref{fig:Scheme} and, finally, the positions of all plates in the intermediate stack are fixed with UV-cured optical glue NOA65 ~\cite{Tho} applied to both opposite short sides, see Fig.~\ref{fig:InterStack}.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig4.png}
\caption{\label{fig:InterStack} An intermediate stack of 25 sapphire plates. The neutron beam is incident on the long side ($80~mm$). The position of each individual plate is laser controlled according to the scheme shown in Fig.~\ref{fig:Scheme}. Ultraviolet cured glue is applied to both opposite short sides ($25~mm$).}
\end{figure}

Further assembling of polarizing cassettes composed of intermediate stacks also was performed in the same ``clean room'' with the optical control and under an applied load, see Fig.~\ref{fig:Assembling}. Intermediate stacks were inserted between two optically polished flats made of Borofloat glass and mounted on top of each other. The Borofloat flats and the cassette body made from a B-Al compound serve also as a neutron diaphragm absorbing neutrons outside the polarizer aperture. Two pneumatic actuators apply homogeneous load to the cassette ($\sim 1~bar$) in order to minimize possible gaps between the plates. The fully assembled cassette of plates is fixed with non-magnetic screws.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig5.png}
\caption{\label{fig:Assembling} Final assembling of the polarizer cassette. Intermediate stacks are confined between two thick ($25~mm$) Borofloat glass flats coated with Al. A green-line laser beam incident on the upper flat and the reflected beam are registered with a photo-camera. Two pneumatic actuators apply homogeneous pressure ($\sim 1~bar$) on the cassette.}
\end{figure}

\subsection{\label{sec:Neutron test}Neutron test of the assembly accuracy}

We may suspect that the optical inspection of the assembling described above is valid only locally, within the laser spot size of $\sim 1~mm$. The global slope (averaged over the full plate surface) may be different. Therefore, we also performed neutron tests of the assembly quality at the Super-Adam reflectometer at the ILL ~\cite{Dev2013rsi}.

A fully assembled cassette of 440 double-sided coated plates was installed in the target position of the instrument. A very narrow neutron beam (width $0.1~mm$, horizontal angular divergence $0.05~mrad$ FWHM, height $60~mm$) with the wavelength of $\lambda =0.5~nm$ was incident on the cassette. After preliminary alignment, the cassette was tilted by an angle of $\sim 7~mrad$ from the incident beam direction. This angle is close to the value $\theta_d=d/L=7.2~mrad$ needed to avoid direct transmission, although a small admixture of neutrons having experienced double and zero reflections is possible due to the geometrical imperfections of the plates.

The angular distribution of neutrons having passed through the cassette is projected on a position-sensitive detector (PSD) with a position resolution of $2.8~mm$ FWHM, installed at distance $r$ from the cassette (Cassette \#1: $r=2500~mm$, Cassette \#2: $r=3250~mm$). During the experiment, we keep the incident beam position and the PSD position, while the cassette position is scanned across the beam with a step of $0.05~mm$. The full range of the cassette position scan is $440\times 0.18~mm = 80~mm$. The data were accumulated in two-dimensional matrices: cassette position versus PSD pixel number, see Fig.~\ref{fig:CassetteScan}.

\begin{figure*}
\centering
\includegraphics[width=\textwidth]{Fig6.png}
\caption{\label{fig:CassetteScan} Two-dimensional matrix representing the angular distribution of neutrons reflected by the mirrors of the 440 individual plates in Cassette \#1 (Left) and Cassette \#2 (Right). The solid white line shows the projection on the horizontal axis. See text for details.}
\end{figure*}

Data for Cassette \#1 were re-binned to the same sample-detector distance $r\approx 3250~mm$ as for Cassette \#2. The bright spots near PSD pixel $\sim 700$ are from neutrons having experienced a single reflection by the mirrors. Much weaker spots near PSD pixel $\sim 870$ are from neutrons having experienced zero reflection. As it is common in reflectometry, the distance $\Delta$ between the position of zero reflection and the single reflection spot is related to the mirror slope $\theta$ as follows:
\begin{equation}
\Delta \approx 2\theta r.
\label{eq:Delta2}
\end{equation}

Note that for the parameters of our experiment, the positions of the zero-reflection spots are independent of the mirror slope, and the width of the spot is dominated by the PSD's finite resolution, $\sigma_{\rm PSD}\approx 4.25$ pixels, or $\sim 0.37~mrad$.

In contrast, the positions of the single reflection spot are defined by the angles of the individual mirrors.

Since the incident beam width is $0.1~mm$, the cassette position step $0.05~mm$, and the plate thickness $\sim 180~\mu m$, the beam often illuminates two adjacent plates simultaneously resulting in an additional broadening of the spot or even a spot splitting due to an eventual difference of slopes. At the same time, the width of the narrowest spots is driven by the PSD resolution and the mirror waviness

We observed that due to the mechanical polishing our sapphire substrates are typically thinner near the edges than they are in the central region. This difference in the thickness is $\sim 6~\mu m$. Reflection of neutrons from a concave surface seen during their propagation through the plate would result in focusing in space and in the defocusing (additional broadening) in angle.

From the data shown in Fig.~\ref{fig:CassetteScan}, we found that the typical width of the most narrow spots (the beam illuminates a single mirror) is very close to $\sigma_{PSD}$ that allows us to conclude that the individual mirror waviness of our sapphire substrates play a minor role in the formation of the reflected beam angular distribution

By projecting the matrix data on the horizontal axis we obtain the effective angular distribution of neutrons reflected by the mirrors of all 440 plates. These angular distributions measured for both cassettes are shown in Fig.~\ref{fig:CassetteScan} with solid white lines.

By fitting the single reflection peak near pixel $\sim 700$ with a Gaussian we obtain the estimates of standard deviations $\sigma_\theta^1$ and $\sigma_\theta^2$ for the distribution of individual slopes in Cassettes \#1 and \#2:
\begin{equation}
\sigma_\theta^1=0.62 ~ mrad,\quad \sigma_\theta^2=1.02 ~ mrad.
\label{eq:sigmas}
\end{equation}

As follows from Eq.~(\ref{eq:sigmas}), Cassette \#2 shows a significantly broader distribution of mirror slopes. This fact may be explained by the difference in the assembling procedure. Indeed, Cassette \#1 was assembled from intermediate stacks in a single run. In contrast, while mounting Cassette \#2, we first assembled and glued two intermediate stacks each composed of 4 small stacks of 25 mirrors. The rest of 240 mirrors was assembled in one run from small intermediate stacks.

In Fig.~\ref{fig:CassetteScan}, positions 1-400 correspond to the first stack of 100 mirrors, positions 401-800 to the second stack of 100 mirrors, and positions 801-1600 to the rest composed of small stacks. In this two-step procedure, an error in the relative positioning of the second big stack would apply to all 100 mirrors in this stack. This fact may explain the asymmetric form of the slope distribution for Cassette \#2, or even the tendency to the splitting visible in Fig.~\ref{fig:CassetteScan}.

In spite of this difference, the width of the slope distribution is in a good agreement with the tolerance window $\pm 1~mrad$ adopted during the assembling of both cassettes.

The angular distribution of individual mirror slopes in the cassette, $\sigma_\theta$, may be translated into the broadening of angular divergence of the incident neutron beam (given in second order):
\begin{equation}
{\rm FWHM}_{\rm eff} \approx {\rm FWHM}_{\rm in} \left( 1+\frac{1}{2}\left( \frac{2.35\sigma_\theta}{{\rm FWHM}_{\rm in}}\right) ^2 \right).
\label{eq:FWHA}
\end{equation}
Here, ${\rm FWHM}_{\rm in}$ is the incident beam angular divergence. For the PF1B guide, the incident beam divergence depends on the neutron wavelength, ${\rm FWHM}_{\rm in}\propto \lambda$, while $\sigma_\theta$ is, as purely geometrical effect, independent of $\lambda$. Therefore, we expect that the effective beam broadening from the polarizer is stronger for short wavelengths.

The relevant wavelength band of the PF1B polarizer is $0.3-2.0~nm$. For neutrons with $\lambda =0.3~nm$, ${\rm FWHM}_{\rm PF1B}\approx 2 m \theta_{Ni} \lambda \approx 20~mrad$ (with $m = 2$ of the H113 SM coating and the critical angle of Ni $\theta_{Ni} =17.3~mrad/nm$ ~\cite{Hay1978jpe}). The effect of additional broadening due to the dispersion of mirror slopes, $\sigma_\theta\approx 1~mrad$, is expected to be about $0.7\%$ for Cassette \#2 and smaller for Cassette \#1, and even smaller for neutrons with longer wavelengths.

Comparing our results (Eq.~(\ref{eq:sigmas})) to the result $\sigma_{\rm coll}\approx 11~mrad$ measured for a stack of 200 Si plates of $0.2~mm$ thickness each, assembled without any control of angular orientation of individual plates ~\cite{Pet2019rsi}, demonstrates the importance and effectiveness of controlling the alignment of individual plates. Here, the plates are coated on both sides with Ti/Gd multi-layers and serve as collimator in a solid-state Fermi chopper. Since ${\rm FWHM}_{\rm coll}$ is comparable to the divergence after a neutron guide, such a collimator causes both, an imperfect collimation because of the transmission of neutrons outside the design divergence of the collimator, and a significant reduction of the on-axis beam intensity because of the absorption of low-divergence neutrons in the coating of misaligned plates.

\subsection{\label{sec:Final assembling}Final assembling of the polarizer}

The two stacks of polarizing mirrors, Cassettes \#1 and \#2, are installed into a mechanical driver one after the other, see Fig.~\ref{fig:FinalAssembly}. The driver allows remote control of each stack's slope angle with respect to the direction of the neutron beam. The driver rotates both cassettes together around axis \#1 (centered at Cassette \#1) and separately Cassette \#2 around axis \#2 (centered at Cassette \#2). The angle between the two cassettes corresponds to the tilt angle $\gamma$, see Fig.~\ref{fig:Vbender}. Here and below we denote this angle $\gamma$, not $\gamma_V$, as we discuss only the V-bender below.

Then this assembly was inserted into the opening of the magnetic housing shown in Fig.~\ref{fig:Magnet}, Left. It is made from permanent magnets (for the details, see Ref. ~\cite{Pet2019rsi}) and provides a very homogeneous vertical field magnetizing the polarizer, with the transversal component $B_x/B_z<0.005$ in most of the volume occupied by the polarizing mirrors and $B_z\approx 0.38~T$.

Finally, neutron shielding composed from boron nitride ceramics was mounted on both sides of the cassettes in order to absorb neutrons beyond the aperture of the polarizing mirrors, see Fig.~\ref{fig:Magnet}, right.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig7.png}
\caption{\label{fig:FinalAssembly} The two polarizing cassettes mounted on the motorized mechanical driver. The motors and encoders are not visible, as they are placed outside the lead shielding where the polarizer is installed. From the motor axes, two ribbed shafts go through holes in the shielding and connect to the mechanics via the two brass hubs visible on the photo.}
\end{figure}

\begin{figure*}
\centering
\includegraphics[width=\textwidth]{Fig8.png}
\caption{\label{fig:Magnet} Left: Sketch of the magnetic housing for the SM polarizer of cold neutrons. Red color indicates the South poles and dense blue color the North poles of the NdFeB magnets~ \cite{Pet2019rsi}. Right: The fully assembled new PF1B polarizer composed of the magnet, the motorized mechanical insert with two polarizing cassettes, and the neutron shield built from boron nitride ceramics. The stacks were illuminated from behind and the light going through the sapphire plates can be seen.}
\end{figure*}

\section{\label{sec:Characterization}Characterization of the new polarizer}

\subsection{\label{sec:Setup}Experimental setup}

The fully assembled polarizer with its magnetic housing was installed into the lead shielding in the PF1B casemate, downstream the H113 neutron guide, see Fig.~\ref{fig:Setup}.

\begin{figure*}
\centering
\includegraphics[width=\textwidth]{Fig9.png}
\caption{\label{fig:Setup} Scheme of the experimental setup for the characterization of the new polarizer at PF1B.}
\end{figure*}

An aperture of $70\times 70~mm^2$ was installed at the exit of the H113 neutron guide (where only $60~mm$ width are illuminated with neutrons). In order to measure time-of-flight (ToF) spectra, a neutron beam chopper with a horizontal slit of $60~mm$ width and $5~mm$ height was installed at a distance of $565~mm$ in front of the polarizer.

An adiabatic fast passage (AFP) neutron spin flipper with a flipping efficiency of $f>0.999$ ~\cite{Kre2005nima} was inserted in the space between the lead housing and the casemate wall. The stray field from the polarizer magnetic housing, the static magnetic field from the AFP flipper, a vertical magnetic field installed in the casemate window, and the magnetic field of the ``Magic box'' ~\cite{Pet2006nima} constitute the guiding field needed to transport adiabatically the neutron polarization. The ``Magic box'' also serves to conserve or flip the $^3$He polarization of the spin filter cell used for polarization analysis.

Both the ``Magic box'' and the neutron detector at its exit were installed on a motorized table in order to allow a horizontal scan of the beam. Neutron ToF measurements without spin filter cell were performed with a low-efficiency ($\sim 5\cdot 10^{-5}$) $^3$He detector. At low efficiency, the number of neutrons crossing the detector is weighted with the $^3$He cross section which grows linearly with neutron wavelength $\lambda$. Measurements with spin filter cell installed were performed with a detector with $\sim 3$\%\ efficiency. Where necessary, the height of the aperture in front of the detector was adapted to keep the dead time correction small.

In this experiment, we did not flip the neutron beam polarization and used the AFP flipper only to provide a static guiding field. Instead, we performed the polarization analysis by flipping the polarization of the  gas in the $^3$He spin filter cell~\cite{Bab2007pb} (polarization losses per flip $\delta <10^{-5}$).

To align the polarizer relative to the beam direction, we first set both cassettes to be parallel to each other. Then we installed a $5~mm$ wide diaphragm behind the chopper thus reducing the beam cross section to $5\times 5~mm^2$. A large area neutron monitor was mounted just behind the polarizer exit to capture the full angular divergence of the incoming beam.

In this configuration, we rotate both cassettes around axis \#1 using the motorized driver \#1 (from $-1.5^\circ$ to $+1.5^\circ$, in steps of $0.1^\circ$). The angular position with the maximum count rate corresponds to both cassettes being parallel to the incoming neutron beam. Then, we scan the angular position of Cassette \#2 keeping unchanged the position of Cassette \#1, in order to correct for a potential initial misalignment between the cassettes. Again, the maximum count rate corresponds to the second cassette being parallel to the first one and both parallel to the incident beam. In the last step, Cassette \#2 was tilted by the angle $\gamma\approx 5d/L\approx 18~mrad$ to prevent ``direct view'', see Fig.~\ref{fig:Scheme}.

\subsection{\label{sec:AngularDistribution}Angular distribution}

Since the polarizer reflection plane is horizontal, the polarizer preserves the vertical angular distribution in the incident neutron beam and modifies only the horizontal one. The latter was measured by means of installing a small pinhole, $5\times 5~mm^2$, at the distance of $50~mm$ behind the chopper, and measuring the count rate in different detector positions across the beam far away from the pinhole using a small-aperture detector ($5~mm$ wide). In this measurement, the neutron detector was installed behind the ``Magic box'' at the distance of $3115~mm$ from the chopper.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig10.png}
\caption{\label{fig:ThreeHills}Angular distribution of neutrons in the horizontal plane behind the polarizer as measured with small apertures. The labels in the format ``a-b'' denote the number of reflections in Cassettes \#1 and \#2, respectively. Negative angles correspond to a detector displacement in the direction of bending with respect to the direct beam.}
\end{figure}

Fig.~\ref{fig:ThreeHills} shows the result of the angular scan for the polarizer tilt angle $\gamma\approx 5d/L$. Contrary to the commonly used C-bender, which shows a continuous angular distribution of reflected neutrons, the V-bender shows a discrete angular distribution for sufficiently large tilt angles. Each peak contains contributions from classes of neutron trajectories with a certain number of reflections in the first and in the second cassette.

The labels in Fig.~\ref{fig:ThreeHills} denote the corresponding reflection numbers. For example, the label \mbox{1-1} corresponds to Garland trajectories with a single reflection in Cassette \#1 and a single reflection in Cassette \#2. The label \mbox{0-2} represents neutrons with Zig-Zag trajectories in Cassette \#2. Note that the position of the peak representing Zig-Zag \mbox{0-2} trajectories is independent of the tilt angle $\gamma$ and is close to the direction of the incident beam, while the positions of the other peaks strongly depend on $\gamma$. The solid line shows the result of multi-peak fitting with a Gaussian form. Trajectories with multiple reflections are suppressed by reflection losses, $R<100\%$, beyond the total reflection regime.

The angular distribution measured with a point-like aperture on the source (in front of the polarizer as in the experiment or equivalently at the polarizer exit) has to be distinguished from the flux distribution $\Phi(x)$ measured for a large source:
\begin{equation}
\Phi(x)=\int\int \frac{\lambda}{\lambda_{th}}B{\rm d}\Omega {\rm d} \lambda,
\label{eq:Phi}
\end{equation}
where $B$ is the brightness of the neutron source ~\cite{Abe2006nima} and $\lambda_{\rm th}=0.18~nm$ is, by convention, the wavelength at the most probable velocity $v_0=2200~m/s$ in a thermal Maxwellian spectrum at the neutron temperature of $300~K$. Only in the ``near zone'' where the position splitting due to different angles in the beam is much smaller than the source size, a position scan provides a true flux density distribution. In contrast, a position scan in the ``far zone'' reproduces an angular distribution similar to Fig.~\ref{fig:ThreeHills}. This fact allows to profit from the full intensity of the beam in the ``near zone'' and to split the beam in well-collimated beams ($\sigma_\theta\approx 2.5~mrad$) in the ``far zone'' without any additional collimator.

\subsection{\label{sec:Transmission}Polarizer transmission}

We used two independent methods to measure the integral transmission of the polarizer (integrated over all neutron wavelengths and angles).

In the ToF method, we keep the chopper with its horizontal slit of $60\times 5~mm^2$ in place and compare intensities measured with the polarizer in and out of the beam (by translating the lead-shielding table holding the polarizer). The chopper slit is smaller than the polarizer of $80\times 80~mm^2$. Therefore, most of the neutrons passing through the chopper also hit the polarizer entrance (no angular collimation other than that from the width of $60~mm$ of the H113 guide was imposed in the horizontal plane). The $^3$He monitor detector (with an aperture of $20~mm$ width and $30~mm$ height) was installed behind the  ``Magic box'', see Fig.~\ref{fig:Setup}.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig11.png}
\caption{\label{fig:HorizontalProfiles}Horizontal profiles of neutron capture flux measured at the distance of $3115~mm$ downstream the chopper: without polarizer (triangles) and downstream the polarizer for two different tilt angles, $\gamma\approx 4.5d/L$ (rectangles) and $\gamma\approx 5d/L$ (circles). Data with the polarizer in place have been scaled by a factor of 5.}
\end{figure}

We performed a horizontal scan of the beam by moving the detector with a step size of $20~mm$, corresponding to the width of the aperture, thus precisely mapping the horizontal axis, and measured ToF spectra at each detector position. Summing-up all channels in the ToF spectra we obtain the neutron count rate profiles shown in Fig.~\ref{fig:HorizontalProfiles}. Note that the data with polarizer in place were multiplied by a factor of 5. Integrating these data over all positions of the detector we found the polarizer integral transmission for the ``good'' spin component (i.e.\ relative to $1/2$ of the intensity of the unpolarized beam):
\begin{equation}
T_1=0.35~\text{for}~\gamma=4.5d/L~\text{, and}~
T_2=0.31~\text{for}~\gamma=5d/L,
\label{eq:Trans}
\end{equation}
where $\gamma$ is the polarizer tilt angle defined in Fig.~\ref{fig:Vbender}.

Using the same data without integration over all neutron wavelengths, we calculate the wavelength spectra of transmitted neutrons for the two polarizer tilt angles, see the experimental points with error bars in Fig.~\ref{fig:Comparison}.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig12.png}
\caption{\label{fig:Comparison} Comparison of the polarizer transmission for the ``good'' spin component measured at PF1B (points with error bars) and that simulated using a MC code (curves). The dashed line is obtained assuming a perfect alignment of the polarizer and reflectivity curve \#1 of Fig.~\ref{fig:Reflectivities}. The solid line corresponds to a small offset in $\gamma$, $\gamma=4.85d/L$, and reflectivity curve \#2 of Fig.~\ref{fig:Reflectivities}.}
\end{figure}

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig13.png}
\caption{\label{fig:Reflectivities} Reflectivity curves of the SM coating for the two neutron spin components, ($R^+$, $R^-$), propagating through a Sapphire substrate. The blue curve \#1 is from simulations performed in ~\cite{Pet2016nima,Pet2019rsi}. The black curve \#2 represents a parametrization ~\cite{Cla1997pb} with adjusted parameters to better match the experimental data in Fig.~\ref{fig:Performance}. See text for details.}
\end{figure}

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig14.png}
\caption{\label{fig:Performance} Comparison of the polarizer performance for selected peaks in the output angular distribution measured at PF1B. Red color corresponds to neutrons with Zig-Zag trajectories, \mbox{0-2}, while blue color corresponds to Garland ones, \mbox{1-1}. Solid lines show a prediction of MC simulations. The decrease of measured polarization for short wavelengths, $\lambda <0.3~nm$, is due to the                   decrease of the $^3$He analyser opacity (which is shifted to longer wavelengths by the finite ToF resolution).}
\end{figure}

First of all, we underline the excellent agreement between the experimental results and the results expected from simulation in the vicinity of the short wavelength cut-off. However, for longer wavelengths, the experimental transmission is systematically lower than the MC prediction; the relative difference is $\sim 10\%$. We do not know exactly the reason for this disagreement. Most probably, it is due to an uncertainty in our knowledge of the SM reflectivity curves for all 900 double-side coated plates as well as due to a dispersion in the mirrors' $m$-values, and due to an uncertainty in the angular alignment of the polarizer cassettes (the zero position found by searching for the maximum in the transmitted intensity has a finite precision). For example, a simulation performed with the slightly modified reflectivity curve shown by line \#2 in Fig.~\ref{fig:Reflectivities} and with a small offset in the tilt angle, $\sim 0.5~mrad$, gives a much better agreement, see the black solid line in Fig.~\ref{fig:Comparison}.

We also confirm that contrary to solid C-benders and S-benders, our V-bender does not show any Bragg dips in the wavelength transmission spectra.

In the second method of evaluation of the polarizer transmission, we measured the neutron capture flux in front and behind the polarizer, without other collimation than the aperture at the exit of the H113 guide, by activating thin Gold foils~\cite{Als1967nima} mounted on the polarizer entrance and exit windows, respectively. The results for the 5 foil positions arranged in a cross are given in Table~\ref{tab:Fluxes}.

\begin{table*}
\caption{\label{tab:Fluxes} Neutron capture fluxes in front and behind the polarizer, in units of $10^9 n/cm^2/s$. We performed all flux measurements at the reactor power of $56~MW$. The Mean values have been scaled to the nominal power of $58.3~MW$. The transmission is calculated for the ``good'' spin component ($1/2$ of the capture flux in front of the polarizer). The flux measured at the end of a collimation system frequently used for neutron decay experiments at PF1B is also given. This collimation system consists of a series of apertures of $6\times 6~cm^2$ installed in a vacuum tube, the first one just after the lead shield at $1.47~m$ and the last one at $4.87~m$ behind the guide exit, compare Fig.~\ref{fig:Scheme}.}
\begin{ruledtabular}
\begin{tabular}{cccccccc}
  Position:& Top & Centre & Bottom & Left & Right & Mean & Position, distance $x$ from guide exit\\
Flux:& 20.1 & 20.4 & 21.5 & 19.1 & 20.1 & 21.1 & Polarizer entrance, $x=0.87~m$ \\
Flux:& 3.65 & 3.53 & 3.63 & 3.21 & 3.12 & 3.57 & Polarizer exit, $x=1.07~m$ \\
Transmission [\%]: & 36.4 & 34.6 & 33.8 & 33.6 & 31.0 & 33.8 & \\\hline\hline
Flux:& 0.59 & 0.64 & 0.61 & 0.63 & 0.66 & 0.65 & End of collimation, $x=4.87~m$ \\
\end{tabular}
\end{ruledtabular}
\end{table*}

The data in Table~\ref{tab:Fluxes} show good transmission homogeneity both in vertical and horizontal direction as well as a reasonable agreement with the results of the ToF method. The small difference between the results of the two methods may be explained by the difference in the angular acceptance: the result Eq.~(\ref{eq:Trans}) was obtained using nearly the total horizontal angular divergence of the beam, which is not fully correct for the results of the gold foil activation shown in Table~\ref{tab:Fluxes}. From the measurements of the integral transmission of the new polarizer as well as from measurements of the transmission as a function of neutron wavelength, we underline the good agreement between MC simulations and experimental data, which is not often the case for such kind of polarizers~\cite{Sha2014nima}.

\subsection{\label{sec:Power}Polarization performance}

The polarization of the neutron beam downstream the polarizer was measured using the setup shown in Fig.~\ref{fig:Setup}. The only difference compared with the transmission experiment is the presence of a cell with Si windows filled with polarized $^3$He gas (length of the gas column: $15~cm$), mounted inside the ``Magic box'' in order to preserve the polarization of the $^3$He.

The polarized $^3$He was produced by Metastable Optical Pumping (MEOP) using the ILL filling station TYREX~\cite{And2005pb,Pet2006pb}. To minimize eventual systematic uncertainties in the measurements of neutron polarization we used the method of opaque cells~\cite{Zim1999plb}. The $^3$He polarization measured optically~\cite{Big1992jp} on TYREX was $0.75$.

The polarization of the neutron beam behind the polarizer was analyzed by means of RF flipping the polarization of the $^3$He gas in the analyzer cell~\cite{Bab2007pb}. The loss in $^3$He polarization per single flip was $<10^{-5}$.

To cover the neutron wavelength range of interest, $0.3-2.0~nm$, we used the following set of $^3$He pressures in the cell: $0.51,~0.82,~2.2~bar$. This set of ``opaque'' $^3$He cells provides $>0.999$ analyzing power for the neutron wavelengths of $>1.0,~0.6,~0.22~nm$, respectively. After filling the cell with polarized $^3$He, it is inserted in a compact magnetic transport system~\cite{Hay1978jpe} and transported to PF1B where it is installed in the ``Magic box''. The spin-relaxation time constant for $^3$He gas in the cell was longer than $200~h$~\cite{Pet2006pb}. Both applied techniques (opaque polarized $^3$He analyzer and in-situ RF flipping of the $^3$He spin state) assure $>0.999$ analyzing power for neutron spin analysis, without any corrections.

\subsubsection{\label{sec:FarZone}Far zone}

As mentioned in Section~\ref{sec:AngularDistribution}, the neutron intensity distribution across the beam in the far zone resolves the angular distribution present after the polarizer. Therefore, we decided to measure the polarization for the two most intense peaks in this angular distribution. These peaks correspond to Garland and Zig-Zag trajectories in the polarizer, marked as \mbox{1-1} and \mbox{0-2} in Fig.~\ref{fig:ThreeHills}, respectively. With a small aperture, $5\times 5~mm^2$, installed just behind the chopper, we measured the neutron angular distribution by means of a detector position scan across the beam at the distance of $3.15~m$ from the chopper. The full range of the scan was $200~mm$ with a step size of $20~mm$; this range corresponds to the beam divergence of $3.7^\circ$. At each point of the scan, we measured ToF spectra for the ``white'' (high transmission) spin state of the $^3$He analyzer. With a detector horizontal aperture of $20~mm$, we were able to fully cover the selected peaks. Finally, we centered the detector to either of the two most intense beams and measured ToF spectra for the two spin states of the analyzer. The measurements were performed using the loop \{``white'', ``black'', ``black'', ``white''\} to minimize possible systematic effects associated with the slow decay of the $^3$He polarization. To partly compensate for the very different count rates for the two spin states of the analyzer (the raw flipping ratio is $\sim 10^3$) we used very different expositions for each analyzer state: \{$30~s$, $1800~s$, $1800~s$, $30~s$\}. Sufficient statistics was accumulated by repeating this sequence for $10-20~h$. In order to preserve a high efficiency of the $^3$He analyzer cell, we replaced the cell with a freshly filled one every $24-48~h$. Note that the neutron transmission of the spin filter cell may change significantly on this time scale, whereas the analyzing power remains stable in the region of interest, where it is in saturation ($A\rightarrow 1$).

The measured polarization (rectangular points) for the Zig-Zag \mbox{0-2} (red points) and Garland \mbox{1-1} (blue points) trajectories are shown in Fig.~\ref{fig:Performance}. First of all, we note the excellent polarization for both selected peaks. For the neutron wavelength band of $0.3-0.6~nm$, corresponding to the intensity maximum of the polarized beam, the measured polarization reaches the value of $P_n\approx 0.999$. The polarization values averaged over all the transmitted spectra are: $P_n\approx 0.9981(1)$ for the \mbox{0-2} Zig-Zag trajectories and $P_n\approx 0.9980(1)$ for the \mbox{1-1} Garland trajectories, where only the statistical uncertainties are given.

As expected, the mean reflection angle for Zig-Zag trajectories is higher and, therefore, the cut-off wavelength is at a longer wavelength than for Garland trajectories. This feature of Zig-Zag trajectories also explains the practically constant polarization (red points) for the full wavelength band $\lambda\in\{0.3~nm-1.9~nm\}$.

\subsubsection{\label{sec:NearZone}Near zone}

In the near zone, the value of interest is the polarization averaged over the full beam (fully illuminated polarizer and all angles of transmitted neutrons). Since the polarizer does not modify neutron trajectories in the vertical plane, we don't expect any variation of the neutron polarization in the vertical direction. Therefore, we used the full horizontal aperture of the chopper ($60\times5~mm^2$) and measured ToF spectra for the two spin states across the full transmitted beam in the horizontal plane. In order to precisely map the beam over its width of $200~mm$, it was scanned with a step size corresponding to the width of the detector aperture, $20~mm$. The data obtained after integration over all positions of the detector at the distance of $3115~mm$ from the chopper are shown in Fig.~\ref{fig:ComparisonBis}.

\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig15.png}
\caption{\label{fig:ComparisonBis} Comparison of the polarizer performance for two different tilt angles $\gamma$ (Red: $\gamma=4.5~d/L$, Blue: $\gamma=5~d/L$). The rectangles with error bars represent the wavelength spectra of neutron polarization (left axis) and the circles the wavelength spectra of capture flux intensity (right axis). The decrease of the measured polarization for short wavelengths, $\lambda<0.3~nm$, is due to the decrease of the $^3$He analyzer opacity (which is shifted to longer wavelengths by the finite ToF resolution).}
\end{figure}

Again, we note the outstanding polarizing power of the new PF1B polarizer even after averaging over the full output phase-space (angle, position, wavelength). It was measured as high as $P_n=0.9960(1)$ for $\gamma=4.5~d/L$ ($16.2~mrad$) and $P_n=0.9974(1)$ for $\gamma=5~d/L$ ($18~mrad$) (where the measured capture flux spectra are used for averaging over the wavelengths).

\section{\label{sec:Adaptability}Polarizer Adaptability}

As mentioned in Section ~\ref{sec:Final assembling}, the new PF1B polarizer is equipped with two motorized drivers, see Fig.~\ref{fig:FinalAssembly}. The V-shape design of the polarizer and the motorization provide the unique opportunity to control remotely the polarizer orientation relative to the incident neutron beam as well as the tilt angle $\gamma$ between the polarizing cassettes (analogous to the bending angle of a classical C-bender).

The commonly accepted criterion for choosing the value of the tilt angle is the critical angle $\gamma_c$ which just prohibits the ``direct view''. In other words, it is the minimal angle which guarantees the absence of neutron trajectories without collisions with the polarizer reflecting mirrors. One may ask the question: is this angle optimal for all types of experiments with polarized neutrons?

Obviously, this is not the case. Indeed, for a long instrument downstream the polarizer, one is interested in the on-axis value $\partial_\Omega\Phi$ ($\Phi$ is the neutron flux density in the beam). An example is the PERKEO~II experiments~\cite{Kre2005plb,Mund:2012fq} which used a well-collimated beam with rather low divergence acceptance. In contrast, for a short instrument, which accepts a high beam divergence, the quantity of interest is the integral flux density $\int_A\Phi{\rm d}A$. These two situations correspond to Far and Near zone after the polarizer.

If considering systematic effects, a very wide class of experiments is statistically limited and systematic uncertainties associated with a spatial or angular non-uniformity of the polarization are not dominant~\cite{Ves2008prc,Gle2017plb,Goe2007plb,Gag2016prc}. For this class of experiments, the so-called Figure-of-Merit (FoM): $\Lambda=P^2T$ is the quantity of interest. The bending angle $\gamma_c$ defined above does not maximize $\Lambda$. On the other hand, experiments which are extremely sensitive to the polarization distribution over the beam cross section or over the emitting angle, profit from an ultra-high beam polarization which leaves no room for noticeable systematic uncertainties.

The data shown in Fig.~\ref{fig:ComparisonBis} were measured for two different tilt angles $\gamma=4.5d/L$ and $\gamma=5d/L$, which are $12\%$ and $20\%$ higher than $\gamma_c=4d/L$ of the ``no direct view'' condition.

The lower the angle $\gamma$ the lower is the beam polarization and the higher is the polarizer transmission or the beam flux density $\Phi$. This typical concurrence implies the existence of an optimal angle $\gamma$ which maximizes the FoM value. There is no reason to expect this optimal value $\Lambda$ to coincide with the value resulting from the ``no direct view'' condition. With the values $P_{\rm ave}$ and $T_{\rm ave}$ shown in Fig.~\ref{fig:ComparisonBis}, we arrive at the following value of the $\Lambda$ parameter: for $\gamma=4.5d/L$, $\Lambda=0.346$, and for $\gamma=5d/L$, $\Lambda=0.312$. This means that even a lower value of $\gamma$ is required to maximize the parameter $\Lambda$. Note that the tilt angle $\gamma=5d/L$ was chosen to provide ultra-high beam polarization, corresponding to what was achieved with the X-SM geometry of two of the previous PF1B benders, where it improves the FoM value substantially compared to $\Lambda_{\rm X-SM}=0.24$ of the X-SM geometry.

Since measurements of the polarizer transmission and especially the polarization are time consuming, we did not perform a full scan over the tilt angle. Instead, we tried to shed a light on this problem using results of MC ray tracing, see Fig.~\ref{fig:Merit}.
\begin{figure}
\centering
\includegraphics[width=\columnwidth]{Fig16.png}
\caption{\label{fig:Merit} Figure-of-Merit $\Lambda$ (blue, left axis) and polarization (red, right axis) as function of the polarizer tilt angle $\gamma$ in units $d/L$. The solid lines show results of MC simulations. The points mark our experimental results for $\Lambda$ (green: transmission from gold foil activation, black: transmission from ToF data). Note that the experimental points are for tilt angles well above the ``no direct view'' condition where the performance of the real device, in particular its polarization, is rather insensitive to small geometrical imperfections. For tilt angles in the transition region these imperfections have to be taken into account.}
\end{figure}
One can see that for the V-bender geometry, the maximum of $\Lambda$ (blue solid line) is reached for tilt angles of about $\gamma=2.5-3.0d/L$ which is far below the value $\gamma=4.0d/L$ required to avoid the ``direct view''. Comparing the $\Lambda$ curve in Fig.~\ref{fig:Merit} with the value $\Lambda=0.477$ measured for the previous PF1B polarizer ~\cite{Sol2002ILL} we conclude that the new polarizer at a tilt angle $\gamma\approx 2.75d/L$ delivers the same Figure-of-Merit $\Lambda$ as the previous one.

This fact opens the possibility to optimize the polarized beam for an extremely broad class of possible experiments using the same polarizing device: either for ultra-high polarization, or for the highest Figure-of-Merit.

More generally, these results show that polarizing devices similar to the one presented here could replace advantageously conventional benders in other types of neutron instruments, even for experiments that are typically flux-limited but do not require the highest level of polarization. These devices give the possibility to tune the polarizer performance for particular experiments depending on its critical requirement (polarization or transmission). More specifically, for neutron scattering experiments where only limited divergence can be used, one could select only the output peak \mbox{0-2} in Fig.~\ref{fig:ThreeHills} where the intensity corresponding to ``zig-zag'' neutron trajectories is concentrated, close to the incident beam direction, with  polarization $0.995-0.999$ over the whole wavelength range (Fig.~\ref{fig:Performance}). By contrast, a C-shaped bender with similar parameters would deviate the whole beam more strongly, giving a continuous outgoing angular distribution~\cite{Soy1995pb} whose total width would be comparable to the present V-bender case~\cite{Pet:un}. The polarizing device could be used either on continuous reactor-based sources or pulsed sources (e.g. spallation), as our ToF measurements show that it can be operated over a broad wavelength range. Another application of this kind of device would be to analyze precisely the beam polarization at a given instrument, without ambiguity and without sophisticated data treatment (assuming that the beam divergence is smaller than the acceptance of the analyzer). Due to the high analyzing efficiency, it could be used the same way as an opaque $^3$He spin filter cell ~\cite{Zim1999plb}, in case the latter is not available or applicable and that an accuracy of a few times $10^{-3}$ is sufficient. A device with smaller beam cross section, easier to install on most instruments, could be built and made available on-demand.

\section{\label{sec:Conclusion} Conclusion}

A new type of solid-state polarizer is built entirely in-house at the ILL for the PF1B cold neutron beam facility. The polarizer is installed in the PF1B casemate and tested in real conditions.

For the tilt angle $\gamma=5 d/L$, in the near zone, the downstream polarization, averaged over the capture spectrum for the full wavelength band of $0.3-2.0~nm$, reaches a record measured value of $P_n=0.997(1)$, with a mean transmission for the ``good'' spin component $>0.31$. In the far zone, the polarization is $P_n>0.998$, and it is practically independent of the neutron wavelength within the wavelength band $\lambda=0.3-1.0~nm$, which contains $0.97$ of the total flux. For longer wavelengths, the polarization shows a very slow decrease towards $0.995$ at the wavelength $\lambda=2~nm$.

The polarizer allows remote control of its geometry (the tilt angle $\gamma$) which opens an unique option to deliver optimal conditions for an extremely broad class of possible experiments using the same polarizing device: either ultra-high polarization or optimal Figure-of-Merit, or the option to adjust the mean take-off angle.

To our knowledge, no device with similar performance endorsed by measurements was reported for a cold neutron polarizing device. The polarizer is based on a series of innovations in the design and fabrication in the following domains: choice of the substrate material, SM and anti-reflecting multilayer coatings, strength and homogeneity of the magnetizing field, and precision of the assembling process.

The polarizer is used for user experiments since the last reactor cycle in 2020.

\begin{acknowledgments}
These measurements were performed at the instruments PF1B, SuperADAM, D17, and T13 at the ILL. We express our gratitude to our technicians Didier Berruyer, Pascal Mouveau and Nicolas Thiery who produced many technical components for the experiments, to Nicolas Surget and Benjamin Sornin for the new control system of the SM coating machine, and to Guillaume Delphin, Amandine Vittoz, Florian Philit and Vincent Gaignon for the production of the SMs by magnetron sputtering. We thank Thomas Saerbeck for useful transmission and reflectivity measurements of substrate materials.
\end{acknowledgments}

\section*{Data Availability Statement}

Data openly available in a public repository that issues datasets with DOIs: doi:10.5291/ILL-DATA.TEST-3099, doi:10.5291/ILL-DATA.3-07-366, doi:10.5291/ILL-DATA.TEST-2541.

\section{References}

redpajama_set_name: RedPajamaArXiv


text:
3:00 pm16 Dec 2009
National Sculpture Garden: Skate At Your Own Risk
I thought ice skating on the National Mall was supposed to be fun. Funny is more like it. Real funny. Why? Because everything that could've gone wrong did.
My friend had entrusted me with the plan making for the evening. It was Saturday night. During the winter. "What could be better than ice skating in the National Sculpture Garden?" I thought. I quickly learned — anything else is apparently BETTER — but I wouldn't have traded the night for anything else.
Overall, I'd say the evening was an epic failure. We stood in line for 40 minutes only to find out that the Pavilion Café was out of hot chocolate. (Who runs out of hot chocolate when you know that's pretty much ALL you sell from November to March?) Then, in the grand attempt to find hot chocolate via the iPhone map app, we were led to a McDonald's that was nowhere to be found. After a bit of research,I now know it exists. Sadly, it's inside the Air & Space Museum and not on the corner of 7th and Independence like the iPhone said it was. Bah humbug I say! Shame on you, iPhone, for killing any holiday spirit we had left.
And then we met the "Skate Master." Yes, that's right, the Skate Master.
We returned to the ice rink with no hot chocolate in hand only to find that a new line had formed. This was no ordinary line. It was a melting-pot mosh-pit of people gazing up at the self-proclaimed Skate Master holding out for a chance to grab their pair of skates. The guy was offering up pairs as if he were an auctioneer, yelling out sizes and handing them out on a "first yell, first serve" basis as folks came off the ice from the previous session.
At least we didn't have to pay the additional $3 skate rental fee (and if we had to, we definitely didn't). I've only skated at the National Mall three times in the four and a half years I've lived in DC. And two of those three times, I've paid $10 to rent skates and slide around the oval rink for two-hours a pop. This time, I only dropped $7. Not too shabby.
Once the two-hour skating session began, the night was looking up a bit. A few laps here, a few laps there — we were semi-content with our evening's choice of entertainment. But of course, we spoke too soon.
Three songs into the night, the music stopped. This left the following sounds: "grumble grumble", "mumble mumble", "shreeeeky shreek", and "THUD" for our ears to consume. I felt trapped inside a fish bowl while several hundred people on the outside were starting at me with a prodding finger.
If the session before 9 pm can have 50's rock, why the hell couldn't we? Several thuds, shreeks, and mumble-grumble's later, it was time for the session break. Now usually I love watching the Zamboni. I can't explain why — though I think it has something to do with my family going ice skating almost every Sunday night when I was a kid. Feels like home somehow. But this time I watched with a dropped jaw. The Zamboni man rushed the job while one of the rink workers decided to pull a Michael J. Fox circa Back to the Future by holding onto the Zamboni's backside, skating around the freshly smoothed ice. If you ask me (and anyone else who was standing near me at the time), that defeats the purpose.
That's not to mention that my friend's skate laces broke while he tried to retie them. I assure you this was not a man-strength mishap, but rather cheap laces failing on us.
Alas — the night wasn't all bad. Sure, there was no hot chocolate and the place was packed full of high schoolers who were pushing each other down every two minutes. I went into the night thinking, "Gee, shucks, this'll be some good-ol',clichéd, wholesome American fun." I didn't get my cliché. I got something better. A night full of mishaps to look back on and laugh.
You win some, you lose some — but Saturday night … I'd say victory was ours … and that's despite the fact my activity planning privileges are now revoked.
All photos by Rachel Levitin.
Rachel Levitin
Rachel moved to DC in the fall of 2005 to study Journalism and Music at American University. When she's not keeping up with the latest Major League Baseball news, she works on making music as an accomplished singer-songwriter and was even a featured performer/speaker at TEDxDupont Circle in 2012. Rachel has also contributed to The Washington Examiner and MASN Sports' Nationals Buzz as a guest blogger. See why she loves DC. E-Mail: rachel@welovedc.com.
This entry was posted in: Night Life, The Features, The Mall
Tagged epic failure, Sculpture Garden Ice Rink
4 thoughts on "National Sculpture Garden: Skate At Your Own Risk"
Skate Troll on December 16, 2009 at 4:15 pm said:
"yraaaaaar I got a pair of ladies 8's!"
Rachel Levitin on December 16, 2009 at 4:19 pm said:
haha guess the Skate Troll found me out :-p
Professor Shoelace on December 19, 2009 at 5:50 pm said:
As they say: "Adventure is not fun while it's happening".
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Rachel moved to DC in the fall of 2005 to study Journalism and Music at American University. When she's not keeping up with the latest Major League Baseball news, she works on making music as an accomplished singer-songwriter and was even a featured performer/speaker at TEDxDupont Circle in 2012. Rachel has also contributed to The Washington Examiner and MASN Sports' Nationals Buzz as a guest blogger. See why she loves DC. E-Mail: rachel@welovedc.com.

redpajama_set_name: RedPajamaCommonCrawl


Marvel's smallest hero is back in action, but he isn't alone: he's joined by a familiar partner in Ant-Man and the Wasp.
Yup, Ant-Man 2 dropped the number to instead market itself as a double-bill, as Paul Rudd's Ant-Man is joined by Evangeline Lilly's Wasp, first teased at the end of the original film.
After Ant-Man was unexpectedly missing from the recent crossover blowout Avengers: Infinity War, the new film is a welcome chance for more silly size-based action in the MCU.
Ant-Man and the Wasp came out in cinemas in July and August 2018 (depending on which side of the Atlantic you're on), which means next on the agenda is the home entertainment release.
The film is available in digital versions and on Blu-ray and DVD in the US, and after a lengthy we wait we can now also buy it on digital or disc here in the UK.
We've seen the film, and you can read our review to find out what we thought - or find out what's in the post-credit scenes if you don't want to sit through the credits yourself.
In the meantime, grab the original Ant-Man from Amazon if you want to remind yourself of how it went, or pick up Captain America: Civil War if you want to watch Ant-Man's most recent on-screen action.
As we've already said, Paul Rudd is back as Scott Lang a.k.a. Ant-Man, joined by Evangeline Lilly's Hope van Dyne - now stepping up to join the action as The Wasp.
Unsurprisingly there are a few other cast members returning from the first film. The most exciting is undoubtedly Michael Peña, whose quick-talking Luis stole every scene he was in last time around, but Judy Greer and Michael Douglas are also back as Scott's ex-wife Maggie and Hope's dad - and the original Ant-Man - Dr. Hank Pym respectively.
We haven't seen everyone before though. The biggest new casting is definitely Michelle Pfeiffer, making her MCU debut as Janet van Dyne - Hope's mother, thought dead, but perhaps just missing in the mysterious Quantum Realm.
She's joined by Laurence Fishburne as another former hero, Goliath, along with Walton Goggins' Sonny Burch, and Hannah John-Kamen as the rather mysterious looking Ghost.
Behind the camera, Peyton Reed is once again directing after successfully taking over from Edgar Wright mid-way through production on the first movie. Luckily, production seems to have been a little smoother this time around.
There's more change on the screenplay front though - of the five writers credited this time, Paul Rudd (yup, the actor) is the only one who also contributed to the original Ant-Man. Despite that, fans might be reassured that among those writers are Chris McKenna and Erik Sommers, who wrote the also-pretty-great Spider-Man: Homecoming, and are working on that film's sequel too.
We've had eight posters for the film so far, with a couple of regular one-sheets (one of which is a smart repeat of the best poster from the first film) and six individual character posters. Those are arguably the most interesting - not least because one gives us our first detailed look at Michelle Pfeiffer in costume as Janet van Dyne.
As the film's release date gets closer, Marvel has finally turned to releasing shorter TV spots for the film too, and here's one pf our favourites: the aptly named 'Fun' spot, which puts the film's sense of humour front and centre, in no small part thanks to the most footage we've had yet of Michael Peña's Luis.
Right, let's talk plot. It should go without saying that this will contain spoilers for Ant-Man, but we'll also discuss other Marvel movies - including Infinity War - so stop reading now if you haven't watched that movie yet.
The biggest thing to know going into Ant-Man and the Wasp is that's it's set before Infinity War, so it doesn't follow up directly on the climax of that film and, you know, the death of half of all living things in the universe.
That doesn't mean it doesn't tie in to Avengers 4 though - there's been a lot of fan speculation that the Quantum Realm - briefly explored in Ant-Man and no doubt more prominent in the sequel - will somehow prove key to undoing Thanos's slaughter in the fourth Avengers film, out next summer.
The trailers already show a few glimpses of the Quantum Realm, and the team travel there to find Hope's mother, Janet van Dyne, and in the process find some tech that could prove crucial in Avengers 4 - or simply accidentally survive the attack from the safety of the parallel dimension.
That might mean the film's ending brings the timeline up to date with Infinity War, revealing what happens to the Ant-Man cast in the process.
That's enough about Infinity War though. What about Ant-Man and the Wasp itself? It looks like there are two villains at play: Walton Goggins' Sonny Burch, and Hannah John-Kamen's Ghost.
The former is seen trying to steal Hank Pym's shrunk-down office in the trailers, though we don't know to what end. As for Ghost, she appears to be the main antagonist, with powers that let her phase through matter at will - perhaps also derived from the Quantum Realm - though we also don't know her aims yet.


text:
Q: What happened to the QGeoMapType? Question is mainly on the title. Details are,
I am asked to convert a slightly old Qt project that is claimed to be compatible with 5.12, which seems it is not, to Qt 5.15 or higher. So, I am debugging errors and I saw,
    #include <QtLocation/private/qgeomaptype_p.h>
...
    QGeoMapType::MapStyle getMapStyle() { return _mapType; }

However, this doesn't work out in Qt 5.15.5. I googled the errors and can't get much.
Error output:
...MapProvider.h:35: error: Use of undeclared identifier 'QGeoMapType'

Okey, after a little more digging I realized that this file is in another directory in my system.
Qt\5.15.2\msvc2019_64\include\QtLocation\5.15.2\QtLocation\private

As you can see, because of 5.15.2 directory it seems Qt can't find the files. After I changed include path to
#include "QtLocation/5.15.2/QtLocation/private/qgeomaptype_p.h"

the filesystem can find it. However, now the problem is Qt can't find some files in qgeomaptype_p.h , all of them are missing QtLocation/5.15.2 prefix.

redpajama_set_name: RedPajamaStackExchange


text:
Steve Chibnall
Search for other papers by Steve Chibnall in
Since his first directorial commission at Welwyn Studios in 1950, Lee Thompson has directed forty-five pictures for theatrical release, covering almost every genre of the cinema. His remarkable ability to adapt his style to suit the material has made him perhaps the most versatile director ever produced by Britain. This book intends to plot the trajectory of a unique film-maker through the typical constraints and opportunities offered by British cinema as a dominant studio system gave way to independent production in the two decades after the Second World War. Thompson was born in Bristol just before the First World War. By the time Thompson left school his ambition was to be an actor, and he joined Nottingham Repertory, making his debut in Young Woodley in 1931. Thompson's opportunity to direct a play came when he received an offer from Hollywood for the film rights to his play Murder Without Crime. His debut box (or ottoman) of tricks went out on the ABC circuit as a double bill with an American film about a GI finding romance in Europe, Four Days Leave. Although the cutting room remained sacrosanct, directors of Thompson's generation had more influence over the final cut of a picture than their predecessors. The Yellow Balloon may be frustratingly limited in its social critique, but as a piece of film making, it was rightly praised for its performances and technical proficiency.
Foreword by Sir John Mills
Chapter 2: From jack of all trades …
Chapter 3: …To master of one
Chapter 4: Women who lie in gaol
Chapter 5: Family entertainment
Chapter 6: Prisons without bars
Chapter 7: The perilous passage
Chapter 8: Deutsche stars
Chapter 9: Greek mythology
Chapter 10: J. Lee goes to Hollywood
Chapter 11: The prodigal's return
Film, Media and Music
American film; British cinema; Carol Reed; Hollywood; Lee Thompson; Midshipman Easy; Murder Without Crime; Second World War; social critique; The Yellow Balloon; versatile director; Young Woodley
Series: British Film-Makers
An enduring legacy
Erik Hedling
This book on Swedish filmmaker Ingmar Bergman contains eighteen new scholarly chapters on the director's work, mainly in the cinema. Most of the contributors—some Swedish, others American or British—have written extensively on Bergman before, some for decades. Bergman is one of the most written-about artists in film history and his fame still lingers all over the world, as was seen in the celebrations of his centenary in 2018. The book was specifically conceived at that time with the aim of presenting fresh angles on his work, although several chapters also focus on traditional aspects of Bergman's art, such as philosophy and psychology. Ingmar Bergman: An Enduring Legacy thus addresses a number of essential topics which have not featured in Bergman studies before, such as the director's relations with Hollywood and transnational film production. It also deals at length with Bergman's highly sophisticated use of film music and with his prominence as a writer of autobiographical literature, as well as with the intermedial relations to his films that this perspective inevitably entails. Finally, the book addresses Bergman's complex relations to Swedish politics. Many different approaches and methods are employed in the book in order to show that Bergman remains a relevant and important artist. The analyses generally focus on some of his most memorable films, like Smiles of a Summer Night, The Seventh Seal, Wild Strawberries, Persona, and Fanny and Alexander; but some rarer material, including Hour of the Wolf, The Lie, and Autumn Sonata, is discussed as well.
British cinema of the 1950s
Ian Mackillop
Neil Sinyard
This book offers a startling re-evaluation of what has until now been seen as the most critically lacklustre period of the British film history. It includes fresh assessment of maverick directors; Pat Jackson, Robert Hamer and Joseph Losey, and even of a maverick critic Raymond Durgnat. The book features personal insights from those inidividually implicated in 1950s cinema; Corin Redgrave on Michael Redgrave, Isabel Quigly on film reviewing, and Bryony Dixon of the BFI on archiving and preservation. A classic image from 1950s British cinema would be Jack Hawkins in The Cruel Sea, the epitome of quiet English integrity. Raymond Durgnat's A Mirror for England: British Movies from Austerity to Affluence, which deals extensively with British films of the 1950s, was written in the mid-1960s and was published in 1970. In a 1947 article called 'Angles of Approach' Lindsay Anderson delivered a fierce attack on contemporary British film culture, outlining a model for a devoted politics of creation, well in line with what we would later understand as auteurism and art cinema aesthetics . The war films of the 1950s together constitute the assented-to record of the emotions and moral judgments called upon to set in order those disorderly events. The book also talks about the Festival of Britain, White Corridors, and four Hamer's post-Ealing films: The Spider and the Fly, The Long Memory, Father Brown and The Scapegoat. A number of factors have contributed to the relative neglect of the 1950s as a decade in British cinema history.
The British monarchy on screen
Mandy Merck
Moving images of the British monarchy, in fact and fiction, are almost as old as the moving image itself, dating back to an 1895 dramatic vignette, The Execution of Mary Queen of Scots. Led by Queen Victoria, British monarchs themselves appeared in the new 'animated photography' from 1896. Half a century later, the 1953 coronation of Elizabeth II was a milestone in the adoption of television, watched by 20 million Britons and 100 million North Americans. At the century's end, Princess Diana's funeral was viewed by 2.5 billion worldwide. Seventeen essays by international commentators examine the portrayal of royalty in the 'actuality' picture, the early extended feature, amateur cinema, the movie melodrama, the Commonwealth documentary, New Queer Cinema, TV current affairs, the big screen ceremonial and the post-historical boxed set. These contributors include Ian Christie, Elisabeth Bronfen, Andrew Higson, Steven Fielding, Karen Lury, Glyn Davis, Ann Gray, Jane Landman, Victoria Duckett, Jude Cowan Montague, James Downs, Barbara Straumann, Deirdre Gilfedder, Jo Stephenson, Ruth Adams, Erin Bell, Basil Glynn and Nicola Rehling.


The LOw Frequency ARray (LOFAR) is a radio telescope working at the lowest frequencies accessible from Earth.
LOFAR-UK is the first major radio telescope to be built in Britain for many decades. Combining thousands of simple dipole receivers with digital signal processing and high-performance computing, LOFAR will be able to survey wide areas of the sky and will open up a new window for astronomers.
LOFAR will undertake a number of key science projects, including pulsars and radio-transients, cosmic-ray studies, ionospheric research and solar physics. Astronomers also hope to detect when the first stars in the Universe were formed and will observe some of the most distant galaxies, revealing more about how the Universe evolved.
The overall LOFAR system comprises many individual arrays of antennas called stations. Each station has two phased arrays, each of which can be digitally controlled to change which part of the sky it is most sensitive to. Additionally, the arrays can be controlled in such a way that they can look in multiple directions at once. The two arrays operate in the VHF radio band. The Low-Band Array (LBA) operates between 30 and 80 MHz and the High-Band Array (HBA) operates from 120 to 240 MHz.
These LOFAR stations are located in several countries in western Europe. The first UK LOFAR station has been built at the Chilbolton Observatory in Hampshire. Like all the other stations, it is linked back to the central computing facility, based at Groningen in the Netherlands, using high-speed network connections. At the core of this network there is a Blue-Gene/P supercomputer which processes and combines the data to generate the final images of the radio sky.
The Chilbolton site, will produce approximately seven petabytes of raw data each year, which will be transferred in real time to Groningen. Together, this pan-European project is the world's largest and most sensitive radio telescope.
LOFAR-UK is a consortium of astronomers representing 22 British Universities, making it the largest radio astronomy consortium in the country. Over 70 leading UK astronomers are directly involved in the project. The LOFAR Chilbolton station was officially opened on the 20 September 2010 by Dame Jocelyn Bell Burnell.


In the second blog in this series, we looked at how you might get a sense of what the current reality around working standards is in your team or organisation. If that exercise – of uncovering current standards – highlighted the need for change, what to do next?
Based on what you found, you may already have ideas on goals to set in the domain of working standards. For my organisation, I'd want something that is not just easy to track at an organisational level, but easy to 'feel' as someone working in the organisation.
The goals you choose need not be the endpoint of what you are trying to achieve with standards in your organisation, just something that is eminently doable and visible to get things rolling.
At this stage, you just want to be building confidence in the team's sense that they can make small changes happen, if they apply themselves. Often the biggest block to making changes is the organisational story about having failed at change in the past, and they'll need confidence and evidence that they can change, later, when bigger challenges come up.
I'd sit with your team, develop as many as you like, then communicate only one obvious one. One that has implications for many other positive results if you get it right.
The famous example of this is from Alcoa. When Paul O'Neill started as CEO, he set only one goal – workplace safety. Apart from no dead bodies in the way of smooth production, the ripples of that goal had so many positive knock-on effects that the company went on to dramatically outperform its peers and the market for the decade that followed. Although the goal seemed irrelevant to making bumper profits, it turned out it was instrumental in changing the culture to one that was seriously profitable as a side-effect of getting serious about safety.
In that spirit, how about this as a goal?: 'Number of e-mails older than 48 hours' across the organisation. You could, of course, go for 'inbox zero' but I've noticed that as a goal it can have a distorting impact, in that it has people get too focused on cleaning up their inbox as an end in itself, rather than treating it as what it is; a milestone on the way to clarity and more strategic decision making.
Yes, some might try to game the system by dumping emails into a nearby folder, but most don't have the game to manage that anyway. Besides, the goal is not accompanied by any negative consequences, it is simply a way to check the overwhelm in and/or responsiveness of the organisation.
You can't tell people how to do their work, but you can declare a new standard. Absent a standard, pretty much anything is good enough.
In order to get some buy-in and traction for change, you'd want to discuss and agree on the standard in your team, in light of the potential benefits in terms of stress and responsiveness. Indeed, discussing and agreeing on the new standard is part of what will drive the motivation to learn how to hit it.
Once you declare that standard, it will be useful to offer support on how to get there. More on that next time.
Thanks for continuing this series Ed which I think helps address the challenge that many organisations are facing: how to build (or rebuild) successful, execution-oriented cultures in organisations that are increasingly complex and difficult to manage.
A focus on one or two critical working standards – signature behavioural norms in culture-change speak – is the only way to really shift cultures in such organisations. Shared Values, Beliefs, Attitudes, Opinions, etc. are all important but ultimately culture transformation ensuring that the right behaviours are developed and implemented is what makes the difference; it's what we do and not to what we say and think that delivers results.


text:
Home Cloud
Lenovo Brings Blades to the Desktop
Jeff Burt
Now that blades have proved themselves efficient and cost-effective alternatives in data centers, OEMs are looking to give businesses the option of bringing similar technology to the client environment.
Lenovo Group Ltd., fresh off its purchase of IBMs PC business, this week will announce a reseller agreement with ClearCube Technology Inc., an Austin, Texas, company at the forefront of PC blade technology. At the same time, systems makers IBM, of Armonk, N.Y., and Dell Inc., of Round Rock, Texas, say some customers are using their blade servers to create a bladed PC environment.
The deal between Lenovo and ClearCube will let Lenovo market and sell ClearCube-branded PC blades and management software, a move that will help customers in a number of businesses, including health care, financial services and government, Lenovo officials said.
They said the addition of PC blades to their portfolio is part of an overall strategy launched by Lenovo when it bought IBMs PC division in May for $1.75 billion to offer a wide variety of options. Such a strategy will help Lenovo, now the worlds third-largest PC vendor, differentiate itself from rivals Dell and Hewlett-Packard Co.
PC blades are housed in a centrally stored chassis and hold the key components of the PC, such as the processors, memory, hard drives and applications. ClearCube has pioneered the technology, although HP entered the game last year with its Consolidated Client Infrastructure. ClearCubes offerings include an interface on the back of the chassis, called BackPack, that supplies external connections for the blades, and the Command Port, which provides the connection to a users desktop. The blades can be managed via the companys ClearCube Management Suite.
The technology is similar to thin clients, which also offload key PC components to a back-end server. A primary difference is that while many thin-client users are connected to one shared server, in most PC blade environments, each user is connected to a separate blade. Blades also give users a fuller PC environment, Lenovo officials said. HP offers both blades and thin clients. Lenovo, through the IBM deal, also has a reseller agreement with thin-client vendor Neoware Systems Inc.
Ken Knotts, senior technologist with ClearCube, said initial interest in PC blades centered on cost reduction but in recent years has shifted to security and management. The blades can be centrally managed, and, because the applications, data and hard drives are stored away from users, security is improved.
Oklahoma Heart Hospital has been using ClearCube PC blades for three years and now has about 140 blades running, said Jeff Jones, lead systems engineer. Initially, the Oklahoma City hospital brought in the technology for health reasons—blades located in a server room mean that no system fans are in the operating or patient rooms, Jones said. The hospital since has realized security benefits and, because of rapid growth at the hospital, space advantages.
"We dont have a lot of space here," Jones said. "Were doubling some spaces [with] two people to an office. Were trying to cram a lot of people into a small space. [Having the PC blades] makes for a lot cleaner space."
Susan Whitney, general manager of IBMs eServer xSeries, said in a recent interview that over the past couple of years some customers have been looking to their BladeCenter blade servers to create bladed client environments for increased flexibility and security and reduced costs. IBM Global Services, in conjunction with such partners as virtual machine vendor VMware Inc., is working on programs to help customers create such environments, Whitney said.
Officials with Dell said some customers—particularly in the federal government, where security and space are key issues—have expressed interest in creating a blade client environment using the PowerEdge 1855 blade.
Check out eWEEK.coms for the latest news in desktop and notebook computing.
Jeffrey Burt has been with eWEEK since 2000, covering an array of areas that includes servers, networking, PCs, processors, converged infrastructure, unified communications and the Internet of things.


AnswerGarden » Which words stand out to you from the ISTE Student Standards?...- Plant a Question, Grow Answers! Generate a live word cloud with your audience.
Which words stand out to you from the ISTE Student Standards?
Question: Which words stand out to you from the ISTE Student Standards?


Steve Forbes, chairman of Forbes Media, says the Occupy Wall Street movement has it all wrong. Instead of targeting Wall Street, the protestors should focus their ire on Washington.
"What needs to be done to get this country moving again is to stop Washington's binge spending, stop trashing the dollar, stop crushing healthcare with thousands of pages of regulations, not mention what they're doing to try ruining the financial industry," he tells Yahoo.
While the occupiers say they're working against the wealthiest 1 percent of the population, it's the occupiers themselves who represent 1 percent, Forbes says.
The protestors are unwilling to go after the government because they are backed by unions and others who depend on the public sector, Forbes says.
The issue of taxes is one that's creating divisions even among Republicans, as the congressional supercommittee on budget deficit reduction struggles to reach an agreement by its Nov. 23 deadline.
Some Republican congressmen are now willing to accept certain tax increases in exchange for entitlement reform. And economists of most stripes generally agree that a combination of entitlement reform and tax hikes is needed to control the deficit.


State officials today said major steps had been taken toward the comprehensive trauma system envisioned in 2009 legislation with designation of trauma centers in Little Rock, Pine Bluff and Memphis.
I'm sure it's coincidental that Republicans have been griping recently about a lack of bricks-and-mortar proof of the wisdom of the cigarette tax increase passed to pay for the system. It's coincidental, too, I'd guess, that Gov. Beebe is lauded throughout the news release for the medical advancement.
Arkansas took a major step today toward establishment of a fully-functional, comprehensive trauma system for the state with the announcement of three new designated trauma centers. The three centers, the first of 73 that have indicated that they will be a part of the new system, are the University of Arkansas for Medical Sciences (UAMS) in Little Rock and the Regional Medical Center ("The MED") in Memphis, both designated as Level I centers, and Jefferson Regional Medical Center in Pine Bluff, which will be a Level II center.
A total of $11,425,886.81 in grants has been awarded in the state for training and hospital and ambulance service upgrades since Act 393 of 2009, the Trauma System Act, outlined the model for the new system.
Traumatic injury is the leading cause of death for all Arkansans age 1-44. Until today, Arkansas had no designated trauma centers and is still one of only three states without a fully functioning trauma system.
Halverson said that the comprehensive system has six major components: solid injury prevention programs, a call center, an ambulance and EMS program, the trauma centers, a registry to track injury from beginning to end and rehabilitation for those who need care following an injury, short- or long-term.
For more information about the trauma system in Arkansas, visit www.healthy.arkansas.gov or call the Arkansas Department of Health at 501-683-0707.