Update on Overleaf.

cau-ath-er_i1-0/report.tex

@@ -1,12 +1,5 @@
 \section{Introduction}
 \label{sec:intro}
-\begin{itemize}
-    \item Explain aims of AHEPaM
-    \item Explain main drivers of AHEPaM
-    \item Explain structure of Executive Report
-    \item summarize main properties of AHEPaM in a table
-\end{itemize}
-
 
 \acs{ATHENA}, the Advanced Telescope for High Energy Astrophysics, is the second large-class
 mission (L2) within the \acs{ESA} Cosmic Vision program. Due to steadily increasing cost, ATHENA was redefined into NewAthena in 2023. While the \acs{ATHENA} scientific community had requested the addition of a \acs{ATHENA} High Energy Particle Monitor (\acs{AHEPaM}) to the \acs{ATHENA} spacecraft (\acs{S/C}), this has now been removed from \acs{ESA}'s responsibility. If possible, \acs{AHEPaM} should be provided as a member-state contribution to NewAthena. This document gives a top-level summary of the development of \acs{AHEPaM} for the original \acs{ATHENA} mission. 
@@ -59,8 +52,8 @@ This executive report summarizes the findings of the work performed at \acs{CAU}
 
 \begin{table}[]
     \centering
-    \begin{tabular}{|c|c|c|c|c|} \hline\\
+    \begin{tabular}{|c|c|c|c|c|} \hline
-      Requirement   & Protons & Electrons  & He ions   &  Motivation \\
+      Requirement   & Protons & Electrons  & He ions   &  Motivation \\\hline
       Energy range   & 0.1 - 2.0 GeV & 0.05 - 1.0 GeV  & 1 - 3 GeV   & Fluxes  \\
       Abs. Precision & \acs{N/A} & \acs{N/A}  & \acs{N/A}   & Abs. calibration  \\
       Rel. Precision &  0.5\% & 1\%  & \acs{N/A}   & Spectral shape  \\
@@ -76,7 +69,7 @@ The design of \acs{AHEPaM} was driven by the original measurement requirements w
 
 \begin{figure}
     \centering
-    \includegraphics{cau-ath-er_i1-0/GCR-spectra.pdf}   
+    \includegraphics[width=0.7\linewidth]{cau-ath-er_i1-0/GCR-spectra.pdf}   
     \caption{Measurements of galactic cosmic ray protons (red), electrons (green) and corresponding model fits (green, Helium).}
     \label{fig:GCR-spec}
 \end{figure}
@@ -88,10 +81,25 @@ Energetic particles are typically measured with so-called particle telescopes wh
 \end{equation}
 where $E$ is the particle kinetic energy, $Z$ its nuclear charge, and $n_e$ is the electron density in the detector material, and d$x$ the detector thickness. For example, a 500 MeV proton looses less than 100 keV in a typical silicon solid-state detector (\acs{SSD}). This means that the total energy of a particle in the required energy range can not be measured within a reasonably-sized detector. That the deposited energy is proportional to $Z^2$ assures that protons and Helium nuclei can easily be distinguished. The difficulty lies in separating electrons from protons. If a particle is faster than the speed of light in the detector, it produces Cherenkov radiation. Because electrons in the required energy range basically travel at the speed of light in vacuum, \acs{AHEPaM} also uses this measurement technique to discriminate electrons from protons because the latter are much slower and therefore do not produce Cherenkov radiation. If the particle has enough energy, it can also produce a shower of secondary particles, an effect that is also used in \acs{AHEPaM}. Thus the driving requirements for \acs{AHEPaM} were the large energy range, the high counting statistics, and the discrimination between electrons and protons. These were met by using the combination of mutliple measurement techniques described in the following.
 
-To measure the low fluxes of \acs{GCR} particles \acs{AHEPAM} had to have a large collecting area, and a large field of view (\acs{FOV}), the product is equivalent to the "collecting power" or geometric factor. This is determined by the area of the front and rear detectors of the particle telescope, and by its length. The \acs{AHEPaM} developed in this contract maximizes the geometry factor by its compact design and by allowing to measu
+To measure the low fluxes of \acs{GCR} particles \acs{AHEPaM} had to have a large collecting area, and a large field of view (\acs{FOV}), the product is equivalent to the "collecting power" or geometric factor. This is determined by the area of the front and rear detectors of the particle telescope, and by its length. The \acs{AHEPaM} developed in this contract maximizes the geometry factor by its compact design and by allowing to measure particles from the front and back, thus doubling the geometry factor. To achieve this, it is designed to be symmetric about its middle plane, as can be seen in Fig.\ref{fig:AHEPaM-concept} which shows a \acs{CAD} view of the arrangements of the various detectors in \acs{AHEPaM}. A particle entering \acs{AHEPaM} from the lower left will first trigger the front \acs{SSD} which is shonw in silver-grey. If it is an electron, it will produce Cherenkov radiation in the Cherenkov detector (shown in yellow), whereas slower protons or Helium nuclei will not. The particle then hits the next \acs{SSD} (shown in red), traverses the high-density \acs{BGO} scintillator, the central \acs{SSD}, and exits \acs{AHEPaM} on a "symmetric" path through the following \acs{BGO}, \acs{SSD}, Cherenkov, and final \acs{SSD} on the upper right. This design is extremely compact and thus maximizes the geometric factor of \acs{AHEPaM} and allows determination of the energy losses in multiple detectors. The process of energy loss is stochastic, the distribution of deposited energy is described by the Landau distribution which is so skewed towards larger energy depositions that only its most probable values is defined, but not its mean. Because this could mimick an energy deposition of a heavier particle, the \acs{SSD}s are arranged in back-to-back pairs and the minimum of the energy deposition is used for the data processing in \acs{AHEPaM}. Thus the five detectors seen in Fig.~\ref{fig:AHEPaM-concept} are actually pairs of detectors. The Cherenkov detectors only produces typically 200 photons per electron, they are read out with \acs{PMT}s which provide sufficient amplification of this very weak signal. The energy deposited in the high-density ($\rho =$ 7.13 g/cm$3$) \acs{BGO} is converted into abundant scintillation light by that material which is read out with extremely compact photodiodes. That signal is proportional to the energy that the particle looses in the \acs{BGO}. The central \acs{SSD} performs another precise measurement of the particle's energy loss before it continues into the symmetric part of \acs{AHEPaM}. The energy resolution of an \acs{SSD} is inversely proportional to its area, therefore \acs{AHEPaM}'s \acs{SSD}s are divided into many segments which are amplified and read out separately. This segmentation also allows \acs{AHEPaM} to detect particle showers that high-energy particles can produce when they interact with matter, especially the high-density \acs{BGO}. Figure~\ref{fig:geometry_sketch} shows such an example for a 500 MeV electron. 
 
-
+\begin{figure}
-Explain how we arrived at the current design. Justify.
+\begin{subfigure}[]{0.48\linewidth}
+    \centering
+    \includegraphics[height=6cm,]{cau-ath-ddc-0006_i1-0/media/ahepam-fm_top_telescope.png}
+    \caption{\acs{AHEPaM} detector concept. The front silicon solid-state detector (\acs{SSD}s) is shown in silver-grey, the others are shown in red, Cherenkov detectors in yellow, \acs{BGO} detectors in dark red, and photo-multiplier tubes (\acs{PMT}s) in green. The small white areas on the \acs{BGO} detectors are the photo-diodes.}
+    \label{fig:AHEPaM-concept}
+\end{subfigure}
+\begin{subfigure}[]{0.48\linewidth}
+  \centering
+  %\includegraphics[width=7cm]{../cau-ath-djf-0007_i1-0/media/figs_sim/sim_model_invert.png}
+  \includegraphics[height=5cm]{cau-ath-djf-0007_i1-0/media/figs_sim/shower_el_500MeV.png}
+  \caption{Visualisation of a simulation run with an electron at 500~MeV).}
+  \label{fig:geometry_sketch}
+\end{subfigure}
+\caption{\acs{AHEPaM} combines three differnet measurement techniques.}
+\label{fig:AHEPaM-measurement-concept}
+\end{figure}
 
 Key properties such as mass, power, volume, etc.\,of the AHEPaM developed under this contract are given in Tab.~\ref{tab:key-properties}. 
 
@@ -151,13 +159,6 @@ The proposed sensor design of the \acs{AHEPaM} is sketched in fig. \ref{fig:tele
 
 
 
-\begin{figure}
-  \centering
-  \includegraphics[width=7cm]{../cau-ath-djf-0007_i1-0/media/figs_sim/sim_model_invert.png}
-  \includegraphics[width=7cm]{../cau-ath-djf-0007_i1-0/media/figs_sim/shower_el_500MeV}
-  \caption{left: Sketch of the geometry as integrated in the GEANT4 simulation. Right: Visualisation of a simulation run with an electron  (500~MeV).}
-  \label{fig:geometry_sketch}
-\end{figure}
 
 
 

shared/ahepam-acronyms.tex

@@ -28,6 +28,7 @@
   \acro{BSM}{Bi-level Standard Monitor}
   \acro{CAS}{Chinese Academy of Science}
   \acro{CAST}{China Academy of Space Technology}
+  \acro{CAD}{Computer Aided Design}
   \acro{CAU}{Christian-Albrechts-Universität zu Kiel}
   \acro{CBE}{Current Best Estimate}
   \acro{CC}{Configuration Control}