diff --git a/cau-ath-er_i1-0/report.tex b/cau-ath-er_i1-0/report.tex index db7a6329..a264fb4 100644 --- a/cau-ath-er_i1-0/report.tex +++ b/cau-ath-er_i1-0/report.tex @@ -175,8 +175,9 @@ The design of \acs{AHEPaM} that resulted from this study is shown in Fig.~\ref{f Detailed simulations were performed with \acs{GEANT4} \cite{agostinelli-etal-2003} to determine the geometry factors of different combinations of detectors in \acs{AHEPaM} which are key to understanding the expected performance of \acs{AHEPaM}. The required discrimination between electrons and protons was achieved by selecting a refractive index $n$ of the Cherenkov detector which is close to that of vacuum, i.e., 1. Thus this detector only triggers to protons with kinetic energies above $\sim 3$ GeV, which lies well beyond the maximum of the \acs{GCR} flux. That means that most protons are correctly separated from electrons by this technique alone. Additional measurements in \acs{AHEPaM} further improve this discrimination. The main challenge for \acs{AHEPaM}, however, is to meet the required statistical accuracy, i.e., to acquire sufficient counting statistics to meet the requirements given in Tab.~\ref{tab:orig-meas-req}. To increase counting statistics only particles from one hemisphere were simulated, exploiting the symmetry of \acs{AHEPaM} (see Fig.~\ref{fig:AHEPaM-concept}). Therefore, only results from one hemisphere (i.e., $2\pi$ sr) are reported here. During solar quiet times, i.e., in the absence of a solar particle event, the \acs{GCR} particle radiation background is essentially isotropic. This, however, is also the situation when the count rates are small, in other words, it is the limiting case for determining \acs{AHEPaM}s measuring capabilities. This also means that the $2\pi$-sr results reported here can effectively be doubled, i.e., their uncertainties divided by the appropriate factor, $\sqrt{2}$. We do not correct for this geometric factor in this report because solar particle events can be very an-isotropic during their onset times, i.e., in the first hours of the event. -The concept for \acs{AHEPaM} which was developed in this contract continuously provides two classes of data products, high resolution and high statistics. The high-resolution data product is much better at discriminating between protons and electrons than the high-statistics data product. It requires particles to traverse the entire \acs{AHEPaM} particle telescope, i.e., to hit the front-most and rear-most detectors in fig.~\ref{fig:AHEPaM-concept}. The field of view for this data product is narrow and consequently its geometric factor ("gathering power") is limited, and hence only a small fraction of all particles is measured. The high-statistics data product, on the other hand, provides data at high counting statistics, but at the cost of reduced discrimination between electrons and protons. This is achieved by relaxing the requirement that all detectors of the \acs{AHEPaM} telescope are triggered which results in a larger geometric factor. The measurement capabilities of both data products are summarized in Tab.~\ref{tab:AHEPaM-data-products}. Note that the instruments hard- and software can be designed such that both, the high species-resolution and high statistic mode are performed in parallel. Comparison with the requirements listed in Tab.~\ref{tab:orig-meas-req} shows that \acs{AHEPaM} is close to meeting the measurement requirements for protons. In fact, accounting for the $2\pi$-sr simulation, the high-statistics data products meet the original requirement. It has been also shown that the Helium requirements can be full-filled as long as the proton requirements are met. However, those for electrons can not be met, primarily because their flux is much lower than the proton flux (see Fig.~\ref{fig:GCR-spec}). The flux of electrons in the energy range below about 50 MeV is dominated by solar and Jovian electrons \cite{vogt-etal-2018,eraker-and-simpson-1981}. However, Solar energetic electron events at energies above 1 MeV are measured in the 1970's and 1980's by the MEH experiment at ISEE 3 and show only a few events exceeding energies of 50 MeV (for details see \cite{moses-etal-1989}). Thus, the flux of electrons above 50 MeV is dominated by the slowly varying galactic contribution. Therefore, we propose to relax the requirement on the temporal resolution of the electron flux. Possible time-scales for such re-defined requirements could be linked to physical processes such as Forbush decreases (1 day time resolution) or Carrington rotations (28 days). +The concept for \acs{AHEPaM} which was developed in this contract continuously provides two classes of data products, high resolution and high statistics. The high-resolution data product is much better at discriminating between protons and electrons than the high-statistics data product. It requires particles to traverse the entire \acs{AHEPaM} particle telescope, i.e., to hit the front-most and rear-most detectors in Fig.~\ref{fig:AHEPaM-concept}. The field of view for this data product is narrow and consequently its geometric factor ("gathering power") is limited, and hence only a fraction of all particles is measured. The high-statistics data product, on the other hand, provides data at high counting statistics, but at the cost of reduced discrimination between electrons and protons. This is achieved by relaxing the requirement that all detectors of the \acs{AHEPaM} telescope are triggered which results in a larger geometric factor. The measurement capabilities of both data products are summarized in Tab.~\ref{tab:AHEPaM-data-products}. Note that the instruments hard- and software can be designed such that both, the high species-resolution and high statistic mode are performed in parallel. Comparison with the requirements listed in Tab.~\ref{tab:orig-meas-req} shows that \acs{AHEPaM} is close to meeting the measurement requirements for protons. In fact, accounting for the $2\pi$-sr simulation, the high-statistics data products meet the original requirement. It has been also shown that the Helium requirements can be fulfilled as long as the proton requirements are met. However, those for electrons can not be met, primarily because their flux is much lower than the proton flux (see Fig.~\ref{fig:GCR-spec}). The flux of electrons in the energy range below about 50 MeV is dominated by solar and Jovian electrons \cite{vogt-etal-2018, eraker-and-simpson-1981}. Solar energetic electron events at energies above 1 MeV were measured already in the 1970's and 1980's by the MEH experiment on ISEE 3 and showed only a few events exceeding energies of 50 MeV (for details see \cite{moses-etal-1989}). Thus, the flux of electrons above 50 MeV is dominated by the slowly varying galactic contribution. Therefore, we propose to relax the requirement on the temporal resolution of the electron flux. Possible time-scales for such re-defined requirements should be linked to physical processes such as Forbush decreases (1 day time resolution) or Carrington rotations (28 days). +{\bf Zitate auf vogt-etal-2018, eraker-and-simpson-1981 und moses-etal-1989 ercheinen nur als "0"????} \begin{table}[] @@ -190,7 +191,7 @@ The concept for \acs{AHEPaM} which was developed in this contract continuously p high statistics& 5 bands \@ 10 ks: 1.2\% & 5 bands \@ 50 ks: 5.5\% & 6.8 cm$^2$ sr (uni-directional) \\ & 2 bands \@ 3 ks: 1.4\% & 2 bands \@ 50 ks: 3.5\% & \\\hline \end{tabular} - \caption{Measurement capabilities of the current \acs{AHEPaM} design. Note that geometry factors are given as uni-directional. Because \acs{AHEPaM} measures in both the "forward" and "backward" directions, the geometry factors are effectively doubled.} + \caption{Measurement capabilities of the current \acs{AHEPaM} design. Percent values given are the statistical uncertainties {\bf one-sigma?}. Note that geometry factors are given as uni-directional. Because \acs{AHEPaM} measures in both the "forward" and "backward" directions, the geometry factors are effectively doubled.} \label{tab:AHEPaM-data-products} \end{table} @@ -210,19 +211,22 @@ How could AHEPaM be simplified {\bf Lars: 2-3 Sätze "more space"} -The simulation detailed in section 1 of the \cite{ahepam-djf} has been performed individually with and without a Cherenkov detector in order to investigate whether or not the \ac{AHEPaM} requirements can be full-filled with both setups. The requirement regarding the electron uncertainties has proven to be the most difficult one to achieve due to the contribution of protons to the electron channels. This contamination is significant due to the higher proton flux compared to the electrons expected for the \ac{GCR} (see fig. \ref{fig:GCR-spec}).\newline -While the methods introduced in \cite{ahepam-djf} utilizing thresholds in the different detectors of the instrument have reduced the contamination already significantly even without a Cherenkov detector, this improvement has proven to be insufficient in order to full-fill the given requirements. Introducing the Cherenkov to the setup allowed for a further suppression of the proton contamination and hence significant lower electron uncertainties. Additionally, the Cherenkov allows to separate protons above and below 2~GeV allowing for better energy resolutions up to 2~GeV as well as providing an integral channel for protons above 2~GeV. Hence, from a measurement technique perspective the Cherenkov detector is highly preferred.\newline -From a technical point of view, the Cherenkov detector increases the complexity of the instrument. Especially the high voltage that is necessary in order operate the \ac{PMT} of the Cherenkov detector has to be considered. Furthermore, the Cherenkov detector has to be connected to its \acs{PMT} and the rest of the instrument mechanically and thermally. The technical detailed are further described in section 5 in \cite{ahepam-djf}. It is important to note that Cherenkov detectors have been already used successfully for space mission in the past (including instruments build in Kiel \cite{ahepam-heritage}). \newline -Based on the analysis we have decided that a Cherenkov is recommended in order to full-fill the measurement requirements and that the additional technical efforts are both manageable and appropriate for the benefits. However, a de-scoped version of \ac{AHEPaM} without the Cherenkov detectors has been proven to provide the capabilities of separating electrons from protons utilizing the methods described in \cite{ahepam-djf} based on sufficient statistics which could be achieved by integrating over longer time periods. Given the small temporal variations of electrons in the energy range above 50~MeV this de-scoped version is expected to provide electron fluxes within the required systematical and statistical uncertainty range if the requirements on the integration period for electrons would be relaxed. +Since \acs{AHEPaM} is a scientific instrument, the development of the telescope has been granted the highest priority for long time during the concept design phase. While the detector design matured, the structural design has not been pushed with the same priority. This led to a situation where the mechanical design needed to cope with a finalized telescope design, which led to the documented design in this report. In retrospective it would have been better to better synchronize + +The simulations detailed in section 1 of \cite{ahepam-djf} have been performed individually with and without a Cherenkov detector in order to investigate whether or not the \ac{AHEPaM} requirements can be fulfilled with both setups. The requirement regarding the electron uncertainties has proven to be the most difficult one to achieve due to the contribution of protons to the electron channels. This contamination is significant due to the higher proton flux compared to the electrons expected for the \ac{GCR} (see fig. \ref{fig:GCR-spec}).\newline +While the methods introduced in \cite{ahepam-djf} utilizing thresholds in the different detectors of the instrument have reduced the contamination already significantly even without a Cherenkov detector, this improvement has proven to be insufficient in order to fulfill the given requirements. Introducing the Cherenkov to the setup allowed for a further suppression of the proton contamination and hence significant lower electron uncertainties. Additionally, the Cherenkov allows to separate protons above and below 2~GeV {\bf woanders ist von 3 Gev die Rede} allowing for better energy resolutions up to 2~GeV as well as providing an integral channel for protons above 2~GeV. Hence, from a measurement technique perspective the Cherenkov detector is highly preferred.\newline +From a technical point of view, the Cherenkov detector increases the complexity of the instrument. Especially the high voltage that is necessary in order operate the \ac{PMT} of the Cherenkov detector has to be considered. Furthermore, the Cherenkov detector has to be connected to its \acs{PMT} and the rest of the instrument mechanically and thermally. The technical details are further described in section 5 in \cite{ahepam-djf}. It is important to note that Cherenkov detectors have been already used successfully for space mission in the past (including instruments built in Kiel \cite{ahepam-heritage}). \newline +Based on the analysis we have decided that a Cherenkov is recommended in order to fulfill the measurement requirements and that the additional technical efforts are both manageable and appropriate for the benefits. However, a de-scoped version of \ac{AHEPaM} without the Cherenkov detectors has been proven to provide the capabilities of separating electrons from protons utilizing the methods described in \cite{ahepam-djf} based on sufficient statistics which could be achieved by integrating over longer time periods. Given the small temporal variations of electrons in the energy range above 50~MeV this de-scoped version is expected to provide electron fluxes within the required systematical and statistical uncertainty range if the requirements on the integration period for electrons would be relaxed. \section{Summary, Conclusions, and Outlook} +\label{sec:summary} In the framework of the \ac{AHEPaM} project it has been shown that the presented design is capable of meeting the stated engineering requirements while fulfilling most of the ambitious measurement requirements with the exception of the electron uncertainty in the required temporal resolution. We propose a relaxation of the above-stated temporal resolution since no variation of the observed flux is known to occur on such small time-scales at these high energies. \newline Furthermore, it has been shown that as a simplified design concept, discarding the Cherenkov detector in the instrument set-up provides the opportunity to meet most of the measurement requirements with only marginally increased uncertainties compared to a "full" \ac{AHEPaM} instrument as described above while significantly decreasing the complexity and engineering challenges. Summary -{\bf Paddy: Bitte überprüfe, ob wir woanders auch ein TRL assessment geben und ob die Zahlen konsistent sind.} +{\bf Paddy: Wir haben nirgendwo anders TRL zahlen gegeben. Evtl. lohn es sich hier irgendwo unser heritage document zu zitieren?:\cite{ahepam-heritage}} \newline 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 @@ -231,12 +235,12 @@ We have assessed the \acs{TRL} of the critical subsystems of \acs{AHEPaM} in Tab 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\\ + 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}.} + \label{tab:TRL} \end{table} Next steps diff --git a/shared/sample.bib b/shared/sample.bib index be24f39..18f6090 100644 --- a/shared/sample.bib +++ b/shared/sample.bib @@ -667,7 +667,7 @@ archivePrefix = {arXiv}, @ARTICLE{lotti-etal-2021, author = {{Lotti}, Simone and {D'Andrea}, Matteo and {Molendi}, Silvano and {Macculi}, Claudio and {Minervini}, Gabriele and {Fioretti}, Valentina and {Laurenza}, Monica and {Jacquey}, Christian and {Piro}, Luigi}, title = "{Review of the Particle Background of the Athena X-IFU Instrument}", - journal = {\apj}, + journal = {Astrophys. J.}, keywords = {Astronomical instrumentation, X-ray telescopes, X-ray astronomy, Computational methods, Galaxy clusters, Intracluster medium, 799, 1825, 1810, 1965, 584, 858, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - High Energy Astrophysical Phenomena}, year = 2021, month = mar, @@ -687,7 +687,7 @@ archivePrefix = {arXiv}, @ARTICLE{gastaldello-etal-2022, author = {{Gastaldello}, Fabio and {Marelli}, Martino and {Molendi}, Silvano and {Bartalucci}, Iacopo and {K{\"u}hl}, Patrick and {Grant}, Catherine E. and {Ghizzardi}, Simona and {Rossetti}, Mariachiara and {De Luca}, Andrea and {Tiengo}, Andrea}, title = "{The Origin of the Unfocused XMM-Newton Background, Its Variability, and Lessons Learned for ATHENA}", - journal = {\apj}, + journal = {Astrophys. J.}, keywords = {Particle astrophysics, X-ray detectors, Diffuse x-ray background, X-ray astronomy, 96, 1815, 384, 1810, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena}, year = 2022, month = apr, @@ -723,7 +723,7 @@ archivePrefix = {arXiv}, @ARTICLE{vogt-etal-2018, author = {{Vogt}, A. and {Heber}, B. and {Kopp}, A. and {Potgieter}, M.~S. and {Strauss}, R.~D.}, title = "{Jovian electrons in the inner heliosphere. Proposing a new source spectrum based on 30 years of measurements}", - journal = {\aap}, + journal = {Astron.\& Astrophys.}, keywords = {convection, astroparticle physics, Sun: heliosphere, interplanetary medium, methods: numerical, diffusion}, year = 2018, month = may, @@ -732,13 +732,14 @@ archivePrefix = {arXiv}, pages = {A28}, doi = {10.1051/0004-6361/201731736}, adsurl = {https://ui.adsabs.harvard.edu/abs/2018A&A...613A..28V}, + keywords = {reference}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} } @ARTICLE{eraker-1982, author = {{Eraker}, J.~H.}, title = "{Origins of the low-energy relativistic interplanetary electrons}", - journal = {\apj}, + journal = {Astrophys. J.}, keywords = {Electrons, Interplanetary Medium, Jupiter (Planet), Planetary Radiation, Relativistic Particles, Astronomical Models, Background Radiation, Electron Energy, Electron Flux Density, Particle Telescopes, Pioneer 10 Space Probe, Astrophysics}, year = 1982, month = jun, @@ -746,6 +747,7 @@ archivePrefix = {arXiv}, pages = {862-880}, doi = {10.1086/160036}, adsurl = {https://ui.adsabs.harvard.edu/abs/1982ApJ...257..862E}, + keywords = {reference}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} } @@ -760,12 +762,13 @@ archivePrefix = {arXiv}, month = jan, pages = {279}, adsurl = {https://ui.adsabs.harvard.edu/abs/1981ICRC....3..279E}, - adsnote = {Provided by the SAO/NASA Astrophysics Data System} + adsnote = {Provided by the SAO/NASA Astrophysics Data System}, + keywords = {reference} } @ARTICLE{moses-etal-1989, author = {{Moses}, Dan and {Droege}, Wolfgang and {Meyer}, Peter and {Evenson}, Paul}, title = "{Characteristics of Energetic Solar Flare Electron Spectra}", - journal = {\apj}, + journal = {Astrophys. J.}, keywords = {Electronic Spectra, Energy Spectra, Solar Flares, International Sun Earth Explorer 3, Interplanetary Medium, Satellite-Borne Instruments, Solar Cosmic Rays, Solar X-Rays, Solar Physics, COSMIC RAYS: GENERAL, SUN: FLARES, SUN: PARTICLE EMISSION, SUN: X-RAYS}, year = 1989, month = nov, @@ -773,5 +776,6 @@ archivePrefix = {arXiv}, pages = {523}, doi = {10.1086/168034}, adsurl = {https://ui.adsabs.harvard.edu/abs/1989ApJ...346..523M}, - adsnote = {Provided by the SAO/NASA Astrophysics Data System} + adsnote = {Provided by the SAO/NASA Astrophysics Data System}, + keywords = {reference} }