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new unit for speed of light

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nam
2017-01-27 12:23:12 -05:00
parent 2d693b3a41
commit daee5ed40d
7 changed files with 34 additions and 32 deletions
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32
thesis/chapters/chap3_comet.tex
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@@ -90,8 +90,8 @@ to reduce the radiative pion capture and other prompt backgrounds. Cosmic
backgrounds are
rejected using a combination of
passive shielding, veto counters and reconstruction cuts. The momenta of beam
muons used in the experiment were \SI{52}{\MeV\per\cc} and
\SI{53}{\MeV\per\cc}, and the momentum spread was 2\%.
muons used in the experiment were \SI{52}{\MeV\per\hepclight} and
\SI{53}{\MeV\per\hepclight}, and the momentum spread was 2\%.
\begin{figure}[htbp] \centering
\includegraphics[width=0.85\textwidth]{figs/sindrumII_setup}
\caption{SINDRUM-II experimental set up, reprinted from
@@ -409,9 +409,9 @@ transport section.
The \ang{180} bending electron transport solenoids help remove line-of-sight
between the target and the detector system. It works similarly to the muon
transportation section, but is tuned differently to accept electrons of about
\SI{105}{\MeV\per\cc}. A compensation field of \SI{0.17}{\tesla} along the
\SI{105}{\MeV\per\hepclight}. A compensation field of \SI{0.17}{\tesla} along the
vertical direction will be applied. Electrons with momentum less than
\SI{80}{\MeV\per\cc} are blocked at the exit of this section by
\SI{80}{\MeV\per\hepclight} are blocked at the exit of this section by
a collimator to reduce DIO electrons rate. The net acceptance of signals of
\mueconv is about 0.32, and the detector hit rate will be in the order of
\SI{1}{\kHz} for a muon stopping rate of \SI{E11}{\Hz}.
@@ -429,12 +429,12 @@ active shielding against cosmic rays is considered.
The tracking detector has to provide a momentum resolution less than
%%TODO 350 or 150?
350~\si{\kilo\electronvolt\per\cc} in order to achieve a sensitivity of
350~\si{\kilo\electronvolt\per\hepclight} in order to achieve a sensitivity of
\sn{3}{-17}. There are five stations of straw-tube gas chambers, each provides
two dimensional information. Each straw tube is 5~\si{\milli\meter} in diameter
and has a 25-\si{\micro\meter}-thick wall. According to a GEANT4 Monte Carlo
simulation, a position resolution of 250~\si{\micro\meter} can be obtained,
which is enough for 350~\si{\kilo\electronvolt\per\cc} momentum resolution. The
which is enough for 350~\si{\kilo\electronvolt\per\hepclight} momentum resolution. The
DIO background of 0.15 events is expected.
The electromagnetic calorimeter serves three purposes: a) to measure electrons
@@ -450,11 +450,11 @@ hit positions. Two candidate crystals, GSO and LYSO, are under consideration.
The requirements for \mueconv signals are:
\begin{itemize}
\item from the 350~\si{\kilo\electronvolt\per\cc}~momentum resolution, the signal
region is determined to be 103.5~\si{\mega\electronvolt\per\cc}~to
105.2~\si{\mega\electronvolt\per\cc};
\item from the 350~\si{\kilo\electronvolt\per\hepclight}~momentum resolution, the signal
region is determined to be 103.5~\si{\mega\electronvolt\per\hepclight}~to
105.2~\si{\mega\electronvolt\per\hepclight};
\item transversal momentum of signal electrons is required to be greater than
52~\si{\mega\electronvolt\per\cc} to remove backgrounds from beam electrons and
52~\si{\mega\electronvolt\per\hepclight} to remove backgrounds from beam electrons and
muons decay in flight;
\item timing wise, conversion electrons should arrive in the time window of
detection which is about 700~\si{\nano\second}~after each proton pulses
@@ -675,7 +675,7 @@ avalanche gain of
approximately \sn{4}{4}. A gas mixture of helium:isobutane(90:10) is preferred
since the CDC momentum resolution is dominated by multiple scattering. With
these configurations, an intrinsic momentum resolution of
197~\si{\kilo\electronvolt\per\cc} is achievable according to our tracking study.
197~\si{\kilo\electronvolt\per\hepclight} is achievable according to our tracking study.
\begin{table}[htb]
\begin{center}
@@ -712,7 +712,7 @@ these configurations, an intrinsic momentum resolution of
\label{ssub:hit_rate_on_the_cdc}
The maximal usable muon beam intensity will be limited by the detector hit
occupancy. Charge particles with transversal momentum greater than 70
\si{\mega\electronvolt\per\cc} are expected to reach the CDC. Those include:
\si{\mega\electronvolt\per\hepclight} are expected to reach the CDC. Those include:
protons emitted from nuclear muon capture, and electrons from muon decay in
orbit (DIO). It is calculated that the hit rate due to proton emission dominates,
where the highest rate is \SI{11}{\kHz\per}cell compares to
@@ -733,9 +733,9 @@ $^{28}$Si~\cite{SobottkaWills.1968}. The baseline design for the proton
absorber is 0.5~\si{\milli\meter}-thick CFRP, making the total thickness
of material before the sensitive region is \SI{1.0}{\mm} in CFRP. In this
configuration, the inner wall and the proton absorber contribute a spread of
\SI{167}{\keV\per\cc} to the momentum of a \mueconv signal electron. This
\SI{167}{\keV\per\hepclight} to the momentum of a \mueconv signal electron. This
figure is a little below the spread cause by multiple scatterings on the
chamber gas at \SI{197}{\keV\per\cc}.
chamber gas at \SI{197}{\keV\per\hepclight}.
The impact of the proton absorber on the CDC's hit rate and momentum
resolution is summarised in \cref{tab:comet_absorber_impact}.
\begin{table}[htb]
@@ -745,7 +745,7 @@ resolution is summarised in \cref{tab:comet_absorber_impact}.
\textbf{Absorber }& \textbf{Total CFRP }&\textbf{Proton }&
\textbf{$\Delta p$}\\
\textbf{thickness }& \textbf{thickness }&\textbf{hit rate }& \\
(\si{\mm}) &(\si{\mm}) & (\si{\kHz}) & (\si{\keV\per\cc}) \\
(\si{\mm}) &(\si{\mm}) & (\si{\kHz}) & (\si{\keV\per\hepclight}) \\
\midrule
0 & 0.5 & 130 & 131 \\
0.5 & 1.0 & 34 & 167 \\
@@ -756,7 +756,7 @@ resolution is summarised in \cref{tab:comet_absorber_impact}.
\end{center}
\caption{Hit rates and contributions to momentum spread of the proton
absorber and inner wall of the CDC. The resolutions are calculated for
mono-energetic electrons of \SI{104.96}{\MeV\per\cc}.}
mono-energetic electrons of \SI{104.96}{\MeV\per\hepclight}.}
\label{tab:comet_absorber_impact}
\end{table}

2
thesis/chapters/chap4_alcap_phys.tex
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@@ -813,7 +813,7 @@ A spectrum shape at this energy range is not available.
\label{sub:motivation_of_the_alcap_experiment}
As mentioned, protons from muon capture on aluminium might cause a very high
rate in the COMET Phase-I CDC. The detector is designed to accept particles
with momenta in the range of \SIrange{75}{120}{\MeV\per\cc}.
with momenta in the range of \SIrange{75}{120}{\MeV\per\hepclight}.
\cref{fig:proton_impact_CDC} shows that protons with kinetic energies larger
than \SI{2.5}{\MeV} could hit the CDC. Such events are troublesome due to
their large energy deposition. Deuterons and alphas at the same momentum are

12
thesis/chapters/chap5_alcap_setup.tex
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@@ -29,7 +29,7 @@ scintillators for neutron measurements were also tested in this run.
Muons in the $\pi$E1 beam line are decay products of pions created
as a \SI{590}{\mega\electronvolt} proton beam hits a thick carbon target. The
beam line was designed to deliver muons with momenta ranging from
\SIrange{10}{500}{\mega\electronvolt\per\cc} and momentum spread from
\SIrange{10}{500}{\mega\electronvolt\per\hepclight} and momentum spread from
\SIrange{0.26}{8.0}{\percent}~\cite{Foroughli.1997}. The beam parameters can
be tuned by adjusting magnets and slits along the beam line.
%These parameters can be
@@ -56,7 +56,7 @@ be tuned by adjusting magnets and slits along the beam line.
One of the main requirements of the AlCap experiment was a low energy muon beam
with narrow momentum bite in order to achieve a high fraction of stopping muons
in the very thin targets. In this Run 2013, muons from
\SIrange{28}{45}{\MeV\per\cc} and momentum spread of 1\% and
\SIrange{28}{45}{\MeV\per\hepclight} and momentum spread of 1\% and
3\% were used.
For part of the experiment the target was replaced with one of the silicon
@@ -696,7 +696,7 @@ at X-rays of interest are listed in \cref{tab:xray_eff}.
%\label{sub:muon_momentum_scanning}
%Before taking any data, we carried out the muon momentum scanning to understand
%the muon beam, as well as calibrate the detector system. The nominal muon
%momentum used in the Run 2013 had been tuned to 28~MeV\cc\ before the run. By
%momentum used in the Run 2013 had been tuned to 28~MeV\hepclight\ before the run. By
%changing simultaneously the strength of the key magnet elements in the $\pi$E1
%beam line with the same factor, the muon beam momentum would be scaled with the
%same factor.
@@ -712,8 +712,8 @@ at X-rays of interest are listed in \cref{tab:xray_eff}.
%\toprule
%\textbf{Scaling} & \textbf{Momentum} & \textbf{Kinetic energy}
%& \textbf{Momentum spread}\\
%\textbf{factor} & \textbf{(MeV\per\cc)} & \textbf{(MeV)}
%& \textbf{(MeV\per\cc, 3\% FWHM)}\\
%\textbf{factor} & \textbf{(MeV\per\hepclight)} & \textbf{(MeV)}
%& \textbf{(MeV\per\hepclight, 3\% FWHM)}\\
%\midrule
%1.03 & 28.84 & 3.87& 0.87\\
%1.05 & 29.40 & 4.01& 0.88\\
@@ -790,7 +790,7 @@ sets are shown in \cref{tb:stat}.
\end{tabular}
\end{center}
\caption{Run statistics. Momentum scaling factors are normalised to
\SI{28}{\MeV\per\cc}.}
\SI{28}{\MeV\per\hepclight}.}
\label{tb:stat}
\end{table}

6
thesis/chapters/chap6_analysis.tex
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@@ -244,8 +244,8 @@ In this analysis, a subset of runs from \numrange{2808}{2873} with the
\item a thicker target gives better statistics because of a higher
muon rate available at a higher momentum and less scattering.
\end{itemize}
Muons with momentum of \SI{30.52}{\MeV\per\cc}, 3\%-FWHM spread (scaling factor of
1.09, normalised to \SI{28}{\MeV\per\cc}) were used for this target after
Muons with momentum of \SI{30.52}{\MeV\per\hepclight}, 3\%-FWHM spread (scaling factor of
1.09, normalised to \SI{28}{\MeV\per\hepclight}) were used for this target after
a momentum scanning as described in the next subsection.
\subsection{Momentum scan for the 100-\si{\um} aluminium target}
@@ -260,7 +260,7 @@ in \cref{tab:al100_scan}.
\begin{center}
\begin{tabular}{cccc}
\toprule
\textbf{Momentum (\si{\MeV\per\cc})} & \textbf{Scaling factor} & \textbf{Runs}
\textbf{Momentum (\si{\MeV\per\hepclight})} & \textbf{Scaling factor} & \textbf{Runs}
& \textbf{Length (s)}\\
\midrule
29.12 & 1.04 & \numrange{2609}{2613} &2299\\

10
thesis/chapters/chap7_results.tex
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@@ -84,7 +84,7 @@ different absorber configurations are listed in
%\toprule
%{\textbf{Absorber}} &{\textbf{Inner wall}} & {\textbf{Total CFRP}}& {\textbf{Proton}} & {\textbf{Momentum}} & {\textbf{Integrated charge}}\\
%{\textbf{thickness}} &{\textbf{thickness}} & {\textbf{thickness}}& {\textbf{hit rate}} &{\textbf{spread $\Delta p$}} &{\textbf{300 days}}\\
%{(\si{\mm})} & {(\si{\mm})} & {(\si{\mm})} & {(\si{\Hz})} & {(\si{\keV\per\cc)}} &{(mC/cm)}\\
%{(\si{\mm})} & {(\si{\mm})} & {(\si{\mm})} & {(\si{\Hz})} & {(\si{\keV\per\hepclight)}} &{(mC/cm)}\\
%\midrule
%1 &0.5&1.5 & 2 & 195 & 25\\
%0.5 &0.5&1.0 & 126 & 167 & 60\\
@@ -104,9 +104,9 @@ Therefore the absorber is not necessary as far as the hit rate is concerned.
%absorber is not needed for the COMET Phase I's CDC.
If the proton absorber is not used, the momentum spread of the signal electron
reduces from \SI{167}{\keV\per\cc} to \SI{131}{\keV\per\cc} (\cref{tab:proton_cdc_hitrate}).
reduces from \SI{167}{\keV\per\hepclight} to \SI{131}{\keV\per\hepclight} (\cref{tab:proton_cdc_hitrate}).
This is a small improvement since the momentum resolution is dominated by
intrinsic spread of \SI{197}{\keV\per\cc} due to multiple scattering in gas
intrinsic spread of \SI{197}{\keV\per\hepclight} due to multiple scattering in gas
and wires.
The last column of \cref{tab:proton_cdc_hitrate} shows the integrated charge
@@ -124,7 +124,7 @@ absorber will not worsen the ageing process of the wires.
{\textbf{thickness}} &{\textbf{thickness}} & {\textbf{thickness}}&
{\textbf{spread $\Delta p$}} &{\textbf{300 days}}\\
{(\si{\mm})} & {(\si{\mm})} & {(\si{\mm})}
& {(\si{\keV\per\cc)}} &{(mC/cm)}\\
& {(\si{\keV\per\hepclight)}} &{(mC/cm)}\\
\midrule
1 &0.5&1.5 & 195 & 25\\
0.5 &0.5&1.0 & 167 & 60\\
@@ -137,7 +137,7 @@ absorber will not worsen the ageing process of the wires.
\caption{Momentum spreads due to the inner wall and absorber, and integrated
charge per unit length of wire as calculated in the COMET Phase-I's TDR.
The momentum spreads were calculated for signal electrons at
\SI{104.96}{\MeV\per\cc}. The integrated charge is estimated assuming 300
\SI{104.96}{\MeV\per\hepclight}. The integrated charge is estimated assuming 300
days of operation.}
\label{tab:proton_cdc_hitrate}
\end{table}