cau-ath-er_i1-0/report.tex

@@ -2,7 +2,7 @@
 \label{sec:intro}
 
 \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 \ac{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-funded contribution to NewAthena. This document gives a top-level summary of the development of \acs{AHEPaM} for the original \acs{ATHENA} mission. 
+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 \ac{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. 
 
 \acs{ATHENA} (and NewAthena) will observe the hot and energetic Universe in the X-ray spectral region and has been conceived to address two key questions in modern astrophysics:
 How does ordinary matter form the large-scale structures that we see today?
@@ -18,7 +18,7 @@ The need for \acs{AHEPaM} is driven by the calibration requirements [CAL-BKG-R-0
 The main goal of \acs{AHEPaM} was to ensure that the requirements on the knowledge of the “Non-X-ray Background” (\acs{NXB}) are met. The NXB (also known as “internal particle background”) is due to high-energy particles (primarily Galactic Cosmic Rays (\acs{GCR})) that interact with the spacecraft and instruments and create showers of secondary
 particles. Many of the latter are detected as soft X-ray events. Cosmic ray particles are modulated by the solar cycle because the heliospheric magnetic field, occasianally interrupted by solar particle events which can results in an additional \acs{NXB}. In particular, the \acs{GCR} flux is at a minimum during solar activity maximum and, conversely, the cosmic ray flux is at a maximum during solar activity minimum.
 
-This executive report summarizes the findings of the work performed at \acs{CAU} in a manner suitable for non-experts in the field and is appropriate for publication. It summarizes the key properties of the \acs{AHEPaM} (in Tab.~\ref{tab:key-properties}), describes the design of \acs{AHEPaM}, compares its expected performance with the original measurement requirements, discusses possible future trade studies, and gives an assessment of the current Technology Readiness Level (\acs{TRL}). 
+This executive report summarizes the findings of the work performed at \acs{CAU} in a manner suitable for non-experts in the field and is appropriate for publication. It summarizes the key properties of the \acs{AHEPaM} (in Tab.~\ref{tab:key-properties}), describes the design of \acs{AHEPaM}, compares its expected performance with the original measurement requirements, discusses possible future trade studies, and gives an assessment of the current Technology readiness Level (\acs{TRL}). 
 
 \begin{table}[h]
     \centering
@@ -76,14 +76,14 @@ The design of \acs{AHEPaM} was driven by the original measurement requirements w
     \label{fig:GCR-spec}
 \end{figure}
 
-\acs{AHEPaM} utilizes a combination of \ac{SSD}, \ac{BGO} scintillators and Cherenkov detectors. The combination of these different measurement techniques allows for a separation of high energy electrons and protons. As described further down, protons are easily separated from $\alpha$-particles. Fig.~\ref{fig:basic-arrangement} shows the combination of those different sensors and their mounting (blue) on top of the housing of the different electronics boards (green). The entire instrument will be covered (purple) for thermal reasons and to reduce electromagnetic interference (\acs{EMI}) from other sources. 
+\acs{AHEPaM} utilizes a combination of \ac{SSD}, \ac{BGO} scintillators and Cherenkov detectors. The combination of these different measurement techniques allows for a separation of high energy electrons and protons. As described further down, protons are easily separated from $\alpha$-particles. Fig.~\ref{fig:basic-arrangement} shows the combination of those different sensors and their mounting (blue) on top of the housing of the different electronics boards (green). The entire instrument will be covered (purple) for thermal reasons. 
 
 Energetic particles are typically measured with so-called particle telescopes which combine different kinds of detectors to measure the energy that a particle deposits in the detector. A clever combination allows to determine the particle energy and determine what kind of particle (electron, proton, $\alpha$-particle) it was. Particles in the energy range to be covered by \acs{AHEPaM} typically loose only a fraction of their energy in a detector, this can be approximated\footnote{The energy deposited in a detector can be modeled much more accurately with the sophisticated \acs{GEANT4} simulation package which was developed at \acs{CERN} \cite{agostinelli-etal-2003}. This software package was used extensively in the development of \acs{AHEPaM}.} by the Bethe-Bloch equation, the relevant parts for this discussion are given in eq.~\ref{eq:bethe-bloch},
 \begin{equation}
 \frac{{\rm d}E}{{\rm d}x} \sim \frac{Z^2 n_e}{E},
     \label{eq:bethe-bloch}
 \end{equation}
-where $E$ is the particle kinetic energy, $Z$ its nuclear charge,  $n_e$ 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 (at the same kinetic energy) 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 multiple measurement techniques described in the following and that can be seen in Fig.~\ref{fig:AHEPaM-concept}.
+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 multiple measurement techniques described in the following and that can be seen in Fig.~\ref{fig:AHEPaM-concept}.
 
 \begin{figure}
 \begin{subfigure}[]{0.48\linewidth}
@@ -104,7 +104,7 @@ where $E$ is the particle kinetic energy, $Z$ its nuclear charge,  $n_e$ is the
 \end{figure}
 
 
-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 shown 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 threshold velocity, $v_{th} = c/n$, for producing Cherenkov radiation is determined by the refractive index of the material, $n$. 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 produce 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}. Figure~\ref{fig:geometry_sketch} shows such an example for a 500 MeV electron. 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}. They also allow to correct for variations in the path lengths of individual particle tracks by reconstructing the approximate track geometry from the detector segments that were hit.
+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 shown 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 threshold velocity, $v_{th} = c/n$, for producing Cherenkov radiation is determined by the refractive index of the material, $n$. 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. Figure~\ref{fig:geometry_sketch} shows such an example for a 500 MeV electron.  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}. They also allow to correct for variations in the path lengths of individual particle tracks by reconstructing the approximate track geometry from the detector segments that were hit.
 % measurement technique explained with plot
 \begin{figure}
   \centering
@@ -112,9 +112,8 @@ To measure the low fluxes of \acs{GCR} particles \acs{AHEPaM} had to have a larg
   \caption{Expected count rates as function of the energy losses in BGO2 and BGO1 for penetrating particles utilizing a Cherenkov detector which removes input from ions below 2~GeV/nuc. The rows correspond to 1) proton, 2) helium and 3) electron simulations. The columns are based on 1) the proton, 2) the electron and 3) the helium trigger.}
   \label{fig:pene_supertrigger_cherenkov}
 \end{figure}
-The electro-magnetic showering in the \acs{BGO}, which is more likely for electrons than for ions, allows for separating those species. This effect is shown in Fig. \ref{fig:pene_supertrigger_cherenkov} which shows simulations with expected fluxes (see Fig. \ref{fig:GCR-spec}) of protons (first row), helium particles (second row) and electrons (third row). A pre-selection of particle types has been performed for this plot utilizing different thresholds in the \acp{SSD}, with columns one, two and three presenting the proton, electron and helium pre-selection, respectively. Given the higher flux of protons compared to electrons this pre-selection is obviously not sufficient since protons populate the electron pre-selection (first row, second column). However, using the showering in the \acp{BGO} those particles can be separated in this plot which presents the energy deposition in the second \ac{BGO} (y-axis) vs the first \ac{BGO} (x-axis). The blue box is the proposed electron selection box and it has been shown that the proton contamination in there is only 4\% using the Cherenkov and 28\% without the Cherenkov as an additional selection criteria. As discussed in detail in \cite{ahepam-djf}, this contamination can be corrected for by statistical means.
+The electro-magnetic showering in the \acs{BGO}, which is more likely for electrons than for ions, allows for separating those species. This effect is shown in Fig. \ref{fig:pene_supertrigger_cherenkov} presenting simulations with expected fluxes (see Fig. \ref{fig:GCR-spec}) from protons (first row), helium particles (second row) and electrons (third row). A pre-selection of particle types has been performed for this plot utilizing different thresholds in the \acp{SSD}, with columns one, two and three presenting the proton, electron and helium pre-selection, respectively. Given the higher flux of protons compared to electrons this pre-selection is obviously not sufficient since protons populate the electron pre-selection (first row, second column). However, using the showering in the \acp{BGO} those particles can be separated in this plot which presents the energy deposition in the second \ac{BGO} (y-axis) vs the firts \ac{BGO} (x-axis). The blue box is the proposed electron selection and it has been shown that the proton contamination in there is only 4\% using the Cherenkov and 28\% without the Cherenkov as additional selection criteria. As discussed in detail in \cite{ahepam-djf}, this contamination can be corrected for by statistical means.
-
+The proposed sensor design of the \acs{AHEPaM} is sketched in Fig. \ref{fig:telescope-specs}. The design of the \acp{SSD} is driven by the need of i) defining appropriate opening angles of the telescope and tracking the particles trajectories and ii) removing particles traversing the instrument under oblique angles and thus missing one or more of the detectors. Segmentations in the detectors allows for tracking the particles. Requiring a set combination of these segments in the different detectors also defines the opening angle of the instrument. The \acp{SSD} at location SDB, SDC and SDD have an additional large outer segment which serves as anti-coincidence, i.e. whenever a particles triggers those segments it is discarded. Another detail of the \ac{SSD} setup is that instead of a single \ac{SSD} a stack of two detectors is used (cf. colored positions sketched in Fig. \ref{fig:telescope-specs}). Selecting the minimum of the energy-losses in either of the two reduces the natural distribution of energy-losses caused by the statistical nature of the involved physical processes.
-The proposed sensor design of the \acs{AHEPaM} is sketched in Fig. \ref{fig:telescope-specs}. The design of the \acp{SSD} is driven by the need of i) defining appropriate opening angles of the telescope and tracking the particles trajectories and ii) removing particles traversing the instrument under oblique angles and thus missing one or more of the detectors. Segmentation of the detectors allows for tracking the particles. Requiring a set combination of these segments in the different detectors also defines the opening angle of the instrument. The \acp{SSD} at location SDB, SDC and SDD have an additional large outer segment which serves as an anti-coincidence, i.e. whenever a particles triggers those segments it is discarded. Another detail of the \ac{SSD} setup is that instead of a single \ac{SSD} a stack of two detectors is used (cf. colored positions sketched in Fig. \ref{fig:telescope-specs}). Selecting the minimum of the energy-losses in either of the two reduces the natural distribution of energy-losses caused by the statistical nature of the involved physical processes, i.e., results in narrower distributions and hence better identification of the particle species and primary energy.
 
 
 \begin{figure}[h]
@@ -135,13 +134,13 @@ The proposed sensor design of the \acs{AHEPaM} is sketched in Fig. \ref{fig:tele
 
 Key properties such as mass, power, volume, etc.\,of the AHEPaM developed under this contract are given in Tab.~\ref{tab:key-properties}. One can easily see that \acs{AHEPaM} is indeed very compact and is close to fulfilling the original measurement requirements. It is also clear that it is probably not possible to satisfy all the measurement requirements within the resource allocations foreseen for \acs{AHEPaM}. This is one of the lessons learned from the work performed under this contract. The measurement capabilities of \acs{AHEPaM} are summarized in Tab.~\ref{tab:AHEPaM-data-products} and discussed in more detail in Sec.~\ref{sec:performance}. 
 
-The mechanical, thermal, and electrical interfaces of \acs{AHEPaM} with the \acs{ATHENA} spacecraft were designed to be as straightforward as possible. Due to its allocated mass \acs{AHEPaM}'s mechanical interface consists of 8 separately attached titanium feet. Titanium has been choosen for its high mechanical strength, while providing comparatively low heat conductivity, which helps to thermally decouple the unit from the (usually warmer) mounting panel. This is an important factor in order to reach the detector head's design temperature of 0$^\circ$C. The thermal design furthermore foresees a dedicated external radiator for the \acs{AHEPaM} electronics box, as well as potentially necessary separate detector radiators. The latter consist of, e.g., \acs{OSR} tiles, and are directly attached to the outer instrument cover surfaces shown in purple in Fig.~\ref{fig:ahepam-with-cover}.
+The mechanical, thermal, and electrical interfaces of \acs{AHEPaM} with the \acs{ATHENA} spacecraft were designed to be as straightforward as possible. Due to its allocated mass \acs{AHEPaM}'s mechanical interface consists of 8 separately attached titanium feet. Titanium has been choosen for its high mechanical strength, while providing comparatively low heat conductivity, which helps thermally decoupling the unit from the (usually warmer) mounting panel. An important factor in order to reach the detector head's design temperature of 0$^\circ$C. The thermal design furthermore foresees a dedicated external ebox radiator, as well as potentially necessary separate detector radiators. The latter comprising of e.g. \acs{OSR} tiles, being directly attached to the appropriate instrument cover's outer surfaces.
 
 Structural and thermal modeling was performed to ensure that \acs{AHEPaM} would survive environmental testing as well as the launch and space environment. 
 
 Mechanical ...
 
-Thermal modeling results show that it is possible to approach the above mentioned design temperature in the hot case by using an external {\bf heater ???} with a footprint of ~0.03m$^2$. Consequently during cold phases, where the instrument is not illuminated by the sun, operational heat in the range of ~5W needs to be considered. 
+Thermal results show that it's possible to approach the above mentioned design temperature in the hot case by using an external heater with a footprint of ~0.03m$^2$. Consequently during cold phases, where the instrument is not illuminated by the sun, operational heat in the range of ~5W needs to be considered. 
 
 Due to resource constraints the instrument cover was not part of the \acs{DM}. While a concept has been presented, adequate engineering resources should be budgeted to finalize the design of the cover.
 
@@ -221,26 +220,11 @@ Furthermore, it has been shown that as a simplified design concept, discarding t
 
 Summary
 
-
+Provide assessment of TRL {\bf BEXUS/CHAOS}
-{\bf Paddy: Bitte überprüfe, ob wir woanders auch ein TRL assessment geben und ob die Zahlen konsistent sind.}
-We have assessed the \acs{TRL} of the critical subsystems of \acs{AHEPaM} in Tab.~\ref{tab:TRL}. The overall, wrapped-up \acs{TRL} is driven by the large \acs{SSD}s needed for the current design of \acs{AHEPaM}. A dedicated qualification process for these large detectors would improve that assessment but could not be performed in the course of the development of the \acs{AHEPaM} conceptual study. All other critical subsystems have heritage from previous space missions or from the \acs{CHAOS}/\acs{BEXUS} project which is currently undergoing environmental tests and will be launched in October 2024. This experiment can be considered as a simplified \acs{AHEPaM} which comprises all measurement principles relevant for \acs{AHEPaM} but uses smaller detectors (\acs{SSD}s). The \acs{CHAOS} \acs{BGO} scintillator is identical to the one foreseen for \acs{AHEPaM}, as is its Cherenkov detector. Thus all critical subsystems of \acs{AHEPaM} have been tested with \acs{CHAOS} except for the large (and expensive) \acs{SSD}s. The \acs{DORN} instrument for Chang'E 6 was developed by \acs{IRAP} in Toulouse but uses our front-end electronics (\acs{FEE}) for the detector read out, as it is foreseen for \acs{AHEPaM}.
-\begin{table}[h]
-    \begin{tabular}{|lcp{10cm}|}\hline
-    {\bf Subsystem} & {\bf \acs{TRL}} & {\bf Rationale for \acs{TRL}} \\\hline
-    Electronics & 7 & heritage from \acs{DORN} on Chang'E 6 \\
-    Mechanical design & 5 & heritage from multiple missions \\ \hline
-    Measurement Principle: & & \\
-    Cherenkov detector & 5 & Demonstration with \acs{CHAOS}/\acs{BEXUS}\\
-    BGO scintillator & 6 & Heritage from \acs{MSL}/\acs{RAD}, Solar Orbiter \acs{HET}, and MSL_RAD_plot-2024-02-15--17.png\\
-    Large \acs{SSD}s & 4 & Such \acs{SSD}s are in use at the KArlsruhe TRItium Neutrino (KATRIN) Experiment, but could not be tested in a relevant environment in the \acs{AHEPaM} project.\\ \hline
-    Wraped up  \acs{TRL} & 4 & Lowest \acs{TRL} of all subsystems. \\\hline
-    \end{tabular}
-    \label{tab:TRL}
-    \caption{Summary of subsystem-level \acs{TRL}s and overall \acs{TRL}.}
-\end{table}
 
 Next steps
 
+{\bf nach Baugruppen ordnen}
 
 
 

shared/ahepam-acronyms.tex

@@ -66,7 +66,6 @@
   \acro{DMPL}{Declared Mechanical Parts List}
   \acro{DMS}{Data Management System}
   \acro{Doc.}{Document}
-  \acro{DORN}{Detection of Outgassing RadoN}
   \acro{DPL}{Declared Processes List}
   \acro{DTA}{Damage Thread Assessment}
   \acro{DTCP}{Daily Telemetry Communications Period}
@@ -144,7 +143,6 @@
   \acro{ICRP}{International Commission on Radiological Protection}
   \acro{IDR}{Instituto Universitario de Microgravedad "Ignacio Da Riva"}
   \acro{IEAP}{Institute of Experimental and Applied Physics (CAU)}
-  \acro{IRAP}{Institut de Recherche en Astrophysique et Planétologie}
   \acro{IFKKI}{Institut Für reine und angewandte Kernphysik KIel}
   \acro{IFAR}{Instrument Flight Acceptance Review}
   \acro{IFKKI}{Institut Für reine und angewandte Kernphysik KIel}