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update r15a_gamma report according to Jim's comments

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Nam Tran
2017-05-09 11:59:57 -05:00
parent d793c98663
commit c15636f660
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52
r15a_1809_rate/r15a_gamma.tex
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@@ -119,7 +119,9 @@ pulses from HPGe and \ce{LaBr3} detectors are shown in
\includegraphics[width=1.0\textwidth]{figs/typical_pulses}
\caption{Typical output pulses of HPGe and \ce{LaBr3} detectors: energy
output HPGe high gain (top left), energy output HPGe low gain (top
right), timing output HPGe (bottom left), and \ce{LaBr3} (bottom right).}
right), timing output HPGe (bottom left), and \ce{LaBr3} (bottom right).
Each clock tick corresponds to \SI{10}{\ns} and \SI{2}{\ns} for top and
bottom plots, respectively.}
\label{fig:typical_pulses}
\end{figure}
\end{center}
@@ -127,8 +129,9 @@ pulses from HPGe and \ce{LaBr3} detectors are shown in
The timing pulses from the HPGe detector were not used in this analysis because
they are too long and noisy (see bottom left \cref{fig:typical_pulses}).
Energy of the HPGe detector is taken as amplitude of spectroscopy amplifier
outputs, its timing is determined by the clock tick where the trace passing
\SI{30}{\percent} of the amplitude.
outputs, its timing is determined by the clock tick where the trace passes
\SI{30}{\percent} of the amplitude. The timing resolution is \SI{235}{\ns}
using this method.
\ce{LaBr3} pulses were passed through a moving average window filter (60
samples wide), then integrated to obtain energy resolution.
@@ -141,14 +144,16 @@ position. There was a separate run for background radiation.
\cref{fig:uncalibrated_labr3_spectra} shows \ce{LaBr3}
spectra with calibration sources \ce{^{88}Y}, \ce{^{60}Co}, and background
radiation. It can be seen that the self activation from \ce{Ac} dominates the
spectra. The \SI{1173}{\kilo\eV} peak barely shows up in \ce{^{60}Co}
spectrum, while the \SI{1332}{\keV} peak is buried under the
\SI{1436}{\kilo\eV} peak from \ce{^{138}La}. The \SI{1836}{\kilo\eV}
peak of \ce{^{88}Y} and the annihilation peak \SI{511}{\kilo\eV} can be
distinguished, but the \SI{898}{\kilo\eV} has been distorted by the electrons
and \SI{789}{\kilo\eV} gammas from the beta decay of \ce{^{138}La}. The energy
resolution (FWHM) at the \SI{1836}{\kilo\eV} peak was \SI{5.9}{\percent}.
radiation. It can be seen that below \SI{1.5}{\MeV} region the self activation
from \ce{^{138}La} shows up clearly, and above that products from the chain
decay of \ce{^{227}Ac} dominate the spectrum. The \SI{1173}{\kilo\eV} peak
barely shows up in \ce{^{60}Co} spectrum, while the \SI{1332}{\keV} peak is
buried under the \SI{1436}{\kilo\eV} peak from \ce{^{138}La}. The
\SI{1836}{\kilo\eV} peak of \ce{^{88}Y} and the annihilation peak
\SI{511}{\kilo\eV} can be distinguished, but the \SI{898}{\kilo\eV} has been
distorted by the electrons and \SI{789}{\kilo\eV} gammas from the beta decay of
\ce{^{138}La}. The energy resolution (FWHM) at the \SI{1836}{\kilo\eV} peak was
\SI{5.9}{\percent}.
\begin{center}
\begin{figure}[htbp]
@@ -162,6 +167,7 @@ resolution (FWHM) at the \SI{1836}{\kilo\eV} peak was \SI{5.9}{\percent}.
\end{center}
The HPGe spectra are much cleaner as shown in Figure~\ref{fig:hpge_ecal}.
Energy resolutions are better than \SI{3.2}{\keV} for all calibrated peaks.
\begin{center}
\begin{figure}[htbp]
\centering
@@ -215,12 +221,20 @@ $2p-1s$ & 346.8 & \num{7.26e-4} &\num{4.73e-5} \\
\label{sub:labr3_spectra}
The \ce{LaBr3} energy spectra for the Al dataset are presented in
\cref{fig:labr3_all_al_runs}. The muonic $2p-1s$ peak shows up clearly in
the prompt spectrum as expected. The \SI{1809}{\kilo\eV} peak can be
recognized, it has better
signal-to-background ratio in the prompt spectrum than in the delay spectrum
(0.88 to 0.33). The background under the \SI{1809}{\kilo\eV} is dominated by
the $\alpha$ decay of progenies from \ce{^{227}Ac}. I think that this
\ce{LaBr3} in the current set up is not suitable to use as a STM detector.
the prompt spectrum as expected, the signal-to-background ratio is
\num{3.13(2)}. The \SI{1809}{\kilo\eV} peak can be
recognized, it has better signal-to-background ratio in the prompt spectrum
than in the delay spectrum (0.88 to 0.33). The background under the
\SI{1809}{\kilo\eV} is dominated by
the $\alpha$ decay of progenies from \ce{^{227}Ac}.
It is clear that this
\ce{LaBr3} detector in the current set up is not good enough to measure the
\SI{1809}{\keV} line. The situation of the $2p-1s$ line is a little better, but
more studies is needed to understand the background and possible interferences
around the peak. On another note, there have been steady progress in
manufacturing \ce{LaBr3} detectors, and better performance has been observed.
\begin{center}
\begin{figure}[htbp]
\centering
@@ -288,7 +302,7 @@ Therefore the emission rate per nuclear capture is:
R_{1808.7} = \frac{N_{1808.7}}{A_{1808.7} \times N_{\mu} \times 0.609} = 0.51 \pm 0.05,
\end{equation}
, where the factor 0.609 comes from the fact that only \SI{60.9}{\percent} of
stopped muons are captured. This result is consistent with the rate reported
by Measday et al.
stopped muons are captured. This result is consistent with the rate
\num{0.51(5)} reported by Measday et al.
\end{document}

13
stm_study_201611/stm_study.bib
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@@ -457,6 +457,19 @@
Url = {http://www.sciencedirect.com/science/article/pii/0031916364904792}
}
@TechReport{Bartoszek2014,
Title = {{Mu2e Technical Design Report}},
Author = {Bartoszek, L. and others},
Year = {2014},
Archiveprefix = {arXiv},
Collaboration = {Mu2e},
Eprint = {1501.05241},
Primaryclass = {physics.ins-det},
Reportnumber = {FERMILAB-TM-2594, FERMILAB-DESIGN-2014-01},
Slaccitation = {%%CITATION = ARXIV:1501.05241;%%}
}
@Article{BauerBortels.1990,
Title = {Response of Si detectors to electrons, deuterons and alpha particles},
Author = {Bauer, P and Bortels, G},

210
stm_study_201611/stm_study.tex
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@@ -12,22 +12,40 @@
detect-family=true,
separate-uncertainty=true]{siunitx}
% \usepackage{listings}
\usepackage{xcolor}
\usepackage[dvipsnames]{xcolor}
\usepackage{upquote}
\usepackage{minted}
\usemintedstyle{perldoc}
\usepackage[framemethod=tikz]{mdframed}
\usepackage{adjustbox}
\definecolor{greybg}{rgb}{0.25,0.25,0.25}
\definecolor{yellowbg}{rgb}{0.91, 0.84, 0.42}
\definecolor{bananamania}{rgb}{0.98, 0.91, 0.71}
% \definecolor{greybg}{rgb}{0.25,0.25,0.25}
% \definecolor{yellowbg}{rgb}{0.91, 0.84, 0.42}
% \definecolor{bananamania}{rgb}{0.98, 0.91, 0.71}
\mdfsetup{%
middlelinecolor=red,
middlelinewidth=1pt,
\mdfdefinestyle{warning}{%
linecolor=red!70,
frametitle={Warning},
frametitlerule=true,
frametitlebackgroundcolor=orange!40,
backgroundcolor=orange!30,
innertopmargin=\topskip,
roundcorner=8pt,
linewidth=1pt,
}
% \mdtheorem[style=theoremstyle]{warning}{Warning}
\mdfdefinestyle{listing}{%
linecolor=Aquamarine!50,
linewidth=1pt,
backgroundcolor=yellow!40,
roundcorner=8pt}
roundcorner=8pt,
% frametitlerule=true,
% frametitlebackgroundcolor=yellow!50,
innertopmargin=\topskip,
}
% \mdtheorem[style=listing]{listing}{Listing}
% \DeclareSIUnit\eVperc{\eV\per\clight}
% \DeclareSIUnit\clight{\text{\ensuremath{c}}}
@@ -86,16 +104,16 @@ The study was done using Mu2e Offline version v6\textunderscore
TS5 (see \cref{fig:stm_geo_all}), taking \texttt{cd3-beam-g4s2-mubeam.0728a}
dataset as input. The dataset contains 5098 files, each corresponds to
\num{1e6} proton-on-target (POT). The dataset were reused 16 times with
different random seeds, where \SI{97}{\percent} of runs succeeded, equivalent
to \num{8e11} POTs.
different random seeds, where \SI{97.6}{\percent} of runs succeeded, equivalent
to \num{7.96e10} POTs.
\begin{figure}[htbp]
\centering
\includegraphics[width=1.0\textwidth]{figs/stm_geo_all}
\caption{Simulation geometry showing the DS region on the left, sweeper magnet,
FOV collimator, spot-size collimator, and the STM detectors on the right.
Particles saved in the input files are shoot from the TS5 (orange circle),
and transported to the STM region.}
\caption{Simulation geometry showing the Detector Solenoid region on the
left, sweeper magnet, Field-Of-View collimator, Spot-Size collimator, and
the STM detectors on the right. Particles saved in the input files are
shoot from the TS5 (orange circle), and transported to the STM region.}
\label{fig:stm_geo_all}
\end{figure}
@@ -112,6 +130,8 @@ the output file.
\centering
\caption{List of virtual detectors read out in this study}
\label{tab:vds_list}
\begin{adjustbox}{max width=\textwidth}
\begin{tabular}{@{}ccll@{}}
\toprule
&VDID & Location & Abbreviation \\
@@ -126,6 +146,7 @@ the output file.
8 & 100 & Downstream of the FOV collimator & STM\textunderscore FieldOfViewCollDnStr \\
\bottomrule
\end{tabular}
\end{adjustbox}
\end{table}
\section{Simulation and analysis code}
@@ -135,13 +156,13 @@ The simulation and analysis code are located at:
\url{/mu2e/app/users/namtran/STM_study_201611}.
% \lstinputlisting[language=bash,frame=single]{listings/code_dir_tree.sh}
\begin{mdframed}
\begin{mdframed}[style=listing]
\inputminted[fontsize=\footnotesize]{bash}{listings/code_dir_tree.sh}
\end{mdframed}
\texttt{step00} contains configuration files for this simulation and a script to
submit all 5098 jobs (correspond to number of input files) to the FermiGrid.
It took about 14 hours to complete a job in average.
submit all 5098 jobs to the FermiGrid. It took about 14 hours to complete one
job in average.
The \texttt{analysis} folder contains a script
(\texttt{run\textunderscore statistics.sh}) which checks if a job has finished
@@ -151,25 +172,30 @@ make plots.
\section{Results}
\label{sec:results}
\subsection{STM detector spectra}
\label{sub:stm_detector_spectra}
\begin{mdframed}[style=warning]
Muonic X-rays and probabilities in the simulation are not correct (see
\cref{sec:muonic_x_rays_in_geant4}).
\end{mdframed}
Energy spectrum of particles hitting STM detectors are presented in
\cref{fig:stm_det_ke}. There were not many hits, and only the annihilation
peak stands out. Most of the particles are photons as shown in
\subsection{STM detector energy spectra}
\label{sub:stm_detector_spectra}
Energy spectrum of particles hitting STM detectors in the range
\SIrange{0.1}{3.1}{\MeV} are presented in \cref{fig:stm_det_ke}. There were not many
hits, and only the annihilation peak stands out. Most of the particles are
photons as shown in
\cref{fig:stm_det_ptype}.
\begin{figure}[htbp]
\centering
\includegraphics[width=0.7\textwidth]{figs/ke_det1UpStr}
\includegraphics[width=0.7\textwidth]{figs/ke_det2UpStr}
\includegraphics[width=0.85\textwidth]{figs/ke_det1UpStr}
\includegraphics[width=0.85\textwidth]{figs/ke_det2UpStr}
\caption{Kinetic energy of particles hitting STM detectors 1 (top), and
2 (bottom).}
\label{fig:stm_det_ke}
\end{figure}
\begin{figure}[htbp]
\centering
\includegraphics[width=0.7\textwidth]{figs/ke_pdg_det1UpStr}
\includegraphics[width=0.7\textwidth]{figs/ke_pdg_det2UpStr}
\includegraphics[width=\textwidth]{figs/ke_pdg_det1UpStr}
\includegraphics[width=\textwidth]{figs/ke_pdg_det2UpStr}
\caption{Kinetic energy and type of particles hitting STM detectors 1 (top),
and 2 (bottom).}
\label{fig:stm_det_ptype}
@@ -179,32 +205,138 @@ peak stands out. Most of the particles are photons as shown in
\label{sub:stm_detector_hit_rate_estimation}
The average number of hits on a STM detector per POT is:
\begin{equation}
\frac{888 + 888}{2 \times 8 \times 10^{11}} = 8.7 \times 10^{-9}.
\frac{672 + 714}{2 \times 7.96 \times 10^{10}} = 8.7 \times 10^{-9}.
\label{eqn:stm_hit_count}
\end{equation}
There are 3.1 POTs per proton bunch, so the number of hits per bunch is:
There would be \num{3.1e7} POTs per proton bunch, so the number of hits each
bunch is:
\begin{equation}
8.7 \times 10^{-9} \times 3.1 \times 10^7 = 0.27
8.7 \times 10^{-9} \times 3.1 \times 10^7 = 0.27.
\end{equation}
The instantaneous hit rate, assuming an interval of \SI{1695}{\ns} between
bunches, is:
\begin{equation}
\frac{0.27}{1695\times 10^{-9}} = \SI{159e3}{\Hz}
\frac{0.27}{1695\times 10^{-9}} = \SI{158.9e3}{\Hz}
\end{equation}
\section{Timing of hits on STM detector}
\label{sec:timing_of_hits_on_stm_detector}
The uncertainty on the hit rate estimation is \SI{2.6}{\percent} if
only statistical uncertainty of the hit counting in \cref{eqn:stm_hit_count} is
taken into account. This hit rate is too high for a HPGe detector to function
well, so an attenuator would be installed upstream of the spot-size collimator
to lower the hit rate to about \SI{10}{\kHz}.
\section{Signal to background ratio}
\label{sec:signal_to_background_ratio}
\subsection{Hit timing on STM detectors}
\label{sub:timing_of_hits_on_stm_detectors}
Timing in the simulation starts from the birth of a primary proton, which means
all events start at the same $t = 0$ time. In order to mimic the pulse
structure of the proton beam (\SI{250}{\ns} pulse width, \SI{1695}{\ns} between
pulses~\cite{Bartoszek2014}), the recorded times on each event are smeared by
a Gaussian distribution with a $\sigma = 250 / 6 = \SI{41.7}{\ns}$.
The hit timing as a function of kinetic energy for several virtual detectors
are shown in \cref{fig:ke_time_4vds}. Most of hits arrive between
\num{100} and \SI{400}{\ns} from the center of a proton pulse. Only a few of
particles could hit the STM detectors, especially in the energy region around
the $2p-1s$ peak, that it is hard to investigate the
dependence between timing and energy of hits. Therefore I will only analyze the
timing information of hits STM\_SpotSizeCollUpStr.
\begin{figure}[htbp]
\centering
\includegraphics[width=1.0\textwidth]{figs/ke_time_4vds}
\caption{Hit timing as a function of kinetic energy at spot size
collimator upstream (top left) and down stream (top right), and two STM
detectors (bottom left and right).}
\label{fig:ke_time_4vds}
\end{figure}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\subsection{Signal to background ratio: $2p-1s$ peak at spot-size collimator
upstream}
\label{sub:signal_to_background_ratio_2p_1s_peak_at_spot_size_collimator_upstream}
The energy of muonic $2p-1s$ transition in aluminum is given as \SI{335}{\keV}
by Geant4. Background is taken as the average counts for 10 bins around
\SI{335}{\keV}, and signal strength is calculated by subtracting the background
from the count under the peak. Energy spectra at spot-size
collimator upstream (VD 101: STM\_SpotSizeCollUpStr) in \SI{50}{\ns} windows
and their signal-to-background ratios are shown in
\cref{fig:ke_SpotSizeCollUpStr_time_slices}.
\begin{figure}[htbp]
\centering
\includegraphics[width=1.0\textwidth]{figs/ke_SpotSizeCollUpStr_time_slices}
\caption{Energy spectra at STM\_SpotSizeCollUpStr and signal-to-background
ratios in 50-ns time windows.}
\label{fig:ke_SpotSizeCollUpStr_time_slices}
\end{figure}
\subsection{Signal to background ratio: \SI{1809}{\keV} at spot-size collimator
upstream}
\label{sub:signal_to_background_ratio_1809_kev_at_spot_size_collimator_upstream}
Muonic X-rays and probabilities in the simulation are not correct, see
\cref{sec:muonic_x_rays_in_geant4}.
%%%% Appendices
\pagebreak
\appendix
\section{How to run the simulation and analyze data}
%%%%%%%%%%%%%%%%%%%
\label{sec:how_to_run_the_simulation_and_analyze_data}
\subsection{Simulating beam flash}
\label{sub:simulating_beam_flash}
Simulation scripts are in:
\url{/mu2e/app/users/namtran/STM_study_201611/step00}:
\begin{itemize}
\item \url{fcl/step00.fcl}: configuration for this study (primary particles,
virtual detectors to be read out, particle filtering, ...)
\item \url{geom/geom.txt}: specify geometry settings (thickness
of shields, enabled virtual detectors, ...)
\item \url{submit.sh}: submit all jobs (5098) in the
\url{cd3-beam-g4s2-mubeam.0728a.list} to the grid
\end{itemize}
\noindent Steps to run the simulation:
\begin{itemize}
\item preparing user's code: follow Mu2e instruction to create an
\texttt{Offline} distribution (mine is at
\url{/mu2e/app/users/namtran/Offline}),
\item setting up \texttt{mu2e} environment \footnote{I used \texttt{mu2egrid}
version \texttt{v3\_02\_00} which supports \texttt{mu2eart} command}:
\begin{mdframed}[style=listing]
\inputminted[
fontsize=\scriptsize,
firstline=1,
lastline=11,
breaklines=true,
breakanywhere=true
]{bash}{listings/runall.sh}
\end{mdframed}
\item submitting all jobs:
\begin{mdframed}[style=listing]
\inputminted[
fontsize=\scriptsize,
firstline=13,
breaklines=true,
breakanywhere=true
]{bash}{listings/runall.sh}
\end{mdframed}
\end{itemize}
\noindent Analysis code
\url{/mu2e/app/users/namtran/STM_study_201611/analysis}:
\begin{itemize}
\item \texttt{run\_statistics}: skims the log files (\texttt{mu2e.log} in
each subdirectory`) to make a list of successful runs, and collect CPU
time, random seeds. This script should be run first.
\item \texttt{main.cc}: the analysis code, it is rather simple now, only
exports a few histograms from virtual detector hits. Run \texttt{make}
to produce the executable \texttt{read\_vd}.
\item \texttt{read\_vd}: takes a list of simulation outputs as input to
produce a single ROOT file which contains several histograms.
\end{itemize}
%%%%%%%%%%%%%%%%%%%
\section{Muonic X-rays in Geant4}
\label{sec:muonic_x_rays_in_geant4}
The muonic energy levels and transition probabilities were calculated using
@@ -216,7 +348,7 @@ a simple model described by Mukhopadhyay~\cite{Mukhopadhyay.1977}.
% language=c++, firstline=64, lastline=93,firstnumber=64,
% breaklines=true, breakatwhitespace=true,
% frame=single]{listings/G4EmCaptureCascade.cc}
\begin{mdframed}
\begin{mdframed}[style=listing]
\inputminted[
breaklines=true,
stepnumber=5,
@@ -227,7 +359,7 @@ a simple model described by Mukhopadhyay~\cite{Mukhopadhyay.1977}.
\end{mdframed}
\item Energy of K-shell muons are calculated from energy of K-shell
electrons:
\begin{mdframed}
\begin{mdframed}[style=listing]
\inputminted[
breaklines=true,
stepnumber=5,
@@ -238,7 +370,7 @@ a simple model described by Mukhopadhyay~\cite{Mukhopadhyay.1977}.
\end{mdframed}
\item Energies of muons on other shells are calculated by scaling from that
of K-shell muons:
\begin{mdframed}
\begin{mdframed}[style=listing]
\inputminted[
breaklines=true,
stepnumber=5,