Estimation of the detected background by the future gamma ray transient mission CAMELOT

This study presents a background estimation for the CubeSats Applied for MEasuring and LOcalising Transients (CAMELOT), which is a proposed fleet of nanosatellites for the all-sky monitoring and timing-based localization of gamma ray transients with precise localization capability at low Earth orbits. CAMELOT will allow us to observe and precisely localize short gamma ray bursts (GRBs) associated with kilonovae, long GRBs associated with core-collapse massive stars, magnetar outbursts, terrestrial gamma ray flashes, and gamma ray counterparts to gravitational wave sources. A fleet of at least nine 3U CubeSats is proposed to be equipped with large and thin CsI(Tl) scintillators read out by multipixel photon counters (MPPC). A careful study of the radiation environment in space is necessary to optimize the detector casing, estimate the duty cycle due to the crossing of the South Atlantic Anomaly and polar regions, and minimize the effect of the radiation damage of MPPCs

Athena Charged Particle Diverter (CPD) scientific assessment: preliminary results on the WFI residual background

Soft protons deflected by the CPD can potentially be scattered at lower energy and still reach the detection plane. Proton scattering measurements with samples of the Athena CPD surface, WFI baffle, and other compositions with different levels of roughness are currently being finalized, together with the validation of proton scattering simulations, to study the impact of secondary proton scattering. Preliminary results indicate that protons are indeed scattered with the CPD surface, with a level of mean roughness > tens of nm, with an efficiency almost uniform in scattering angle and large energy losses (>90% at 100 keV). The presence of heavier elements increases the scattering efficiency, while the impact of the roughness is still under investigation. SRIM and Geant4 simulations modelling the surface roughness are currently ongoing, and preliminary SRIM simulations are in general consistent with the measured distributions, but discrepancies in the energy losses are still under study. Preliminary results on the WFI CPD simulation aimed to confirm its compliance with the residual background requirement and to estimate the impact of secondary proton scattering were obtained with a combined simulation of the Athena SPO and the proton interaction with the WFI optical filters and detection plane, assuming no roughness on the exposed surfaces. The statistical uncertainty of the present results, with few protons reaching the WFI, is not yet enough to perform a final CPD scientific assessment and characterization of the secondary proton scattering. We can however conclude with current SRIM simulations that the WFI residual background level), if the CPD is present, is well within the requirement of 5 ✕ 10-4 counts cm-2 s-1 keV-1 in the 2 - 7 keV energy range, with a maximum level of (3.4±2.0) ✕ 10-5 counts cm-2 s-1 keV-1 obtained with only the OBF filter. Most of the protons generating background counts scatter with the filter wheel structure as the last scattering interaction. Current results indicate that no corrective measures are required to minimise the secondary proton scattering or increase the CPD efficiency, but the adoption of vanes or coatings in the filter wheel structure could help reduce the secondary proton flux at the WFI

The peak-flux of GRB 221009A measured with GRBAlpha

The brightest gamma-ray burst ever observed, long-duration GRB 221009A, was detected by GRBAlpha nano-satellite without saturation. We present light curves of the prompt emission in 13 energy bands, from 80 keV to 950 keV, and perform a spectral analysis to calculate the peak flux and peak isotropic-equivalent luminosity. Since the satellite's attitude information is not available for the time of this GRB, more than 200 incident directions were probed in order to find the median luminosity and its systematic uncertainty. We found that the peak flux in the $80-800$ keV range (observer frame) was $F_{\rm{ph}}^{\rm{p}}=1300_{-200}^{+1200}$ ph cm$^{-2}$s$^{-1}$ or $F_{\rm{erg}}^{\rm{p}}=5.7_{-0.7}^{+3.7}\times10^{-4}$ erg cm$^{-2}$s$^{-1}$ and the fluence in the same energy range of the first GRB episode lasting 300 s, which was observable by GRBAlpha, was $S=2.2_{-0.3}^{+1.4}\times10^{-2}$ erg cm$^{-2}$ or $S^{\rm{bol}}=4.9_{-0.5}^{+0.8}\times10^{-2}$ erg cm$^{-2}$ for the extrapolated range of $0.9-8,690$ keV. We infer the isotropic-equivalent released energy of the first GRB episode to be $E_{\rm{iso}}^{\rm{bol}}=2.8_{-0.5}^{+0.8}\times10^{54}$ erg in the $1-10,000$ keV band (rest frame at $z=0.15$). The peak isotropic-equivalent luminosity in the $92-920$ keV range (rest frame) was $L_{\rm{iso}}^{\rm{p}}=3.7_{-0.5}^{+2.5}\times10^{52}$ erg s$^{-1}$ and the bolometric peak isotropic-equivalent luminosity was $L_{\rm{iso}}^{\rm{p,bol}}=8.4_{-1.5}^{+2.5}\times10^{52}$ erg s$^{-1}$ (4 s scale) in the $1-10,000$ keV range (rest frame). The peak emitted energy is $E_p^\ast=E_p(1+z)=1120\pm470$ keV. Our measurement of $L_{\rm{iso}}^{\rm{p,bol}}$ is consistent with the Yonetoku relation. It is possible that, due to the spectral evolution of this GRB and orientation of GRBAlpha at the peak time, the true values of peak flux, fluence, $L_{\rm{iso}}$, and $E_{\rm{iso}}$ are even higher. [abridged]Comment: 7 pages, 7 figures, 1 table, accepted for publication in Astronomy & Astrophysic

Optically read out GEM-based TPC operation and preliminary scintillation studies

The main goal of this project was to realise the reconstruction of tracks in an optically read out GEM (Gas Electron Multiplier) based Time Projection Chamber (TPC). Secondary goal was to initialise a series of systematic studies on the scintillation of particles in Ar/CF4 (80-20%) mixture. Track reconstruction is needed for primary scintillation studies as only tracks fully contained can be considered. A vetoing and trigerring logic was built for the TPC from NIM modules

The HERMES-technologic and scientific pathfinder

HERMES-TP/SP (High Energy Rapid Modular Ensemble of Satellites Technologic and Scientific Pathfinder) is a constellation of six 3U nano-satellites hosting simple but innovative X-ray detectors, characterized by a large energy band and excellent temporal resolution, and thus optimized for the monitoring of Cosmic High Energy transients such as Gamma Ray Bursts and the electromagnetic counterparts of Gravitational Wave Events, and for the determination of their positions. The projects are funded by the Italian Ministry of University and Research and by the Italian Space Agency, and by the European Union's Horizon 2020 Research and Innovation Program under Grant Agreement No. 821896. HERMES-TP/SP is an in-orbit demonstration, that should be tested starting from 2022. It is intrinsically a modular experiment that can be naturally expanded to provide a global, sensitive all sky monitor for high-energy transients

Timing techniques applied to distributed modular high-energy astronomy: the H.E.R.M.E.S. project

The association of GW170817 with GRB170817A proved that electromagnetic counterparts of gravitational wave events are the key to deeply understand the physics of NS-NS merges. Upgrades of the existing GW antennas and the construction of new ones will allow to increase sensitivity down to several hundred Mpc vastly increasing the number of possible electromagnetic counterparts. Monitoring of the hard X-ray/soft gamma-ray sky with good localisation capabilities will help to effectively tackle this problem allowing to fully exploit multi-messenger astronomy. However, building a high energy all-sky monitor with large collective area might be particularly challenging due to the need to place the detectors onboard satellites of limited size. Distributed astronomy is a simple and cheap solution to overcome this difficulty. Here we discuss in detail dedicated timing techniques that allow to precisely locate an astronomical event in the sky taking advantage of the spatial distribution of a swarm of detectors orbiting Earth

GrailQuest and HERMES: hunting for gravitational wave electromagnetic counterparts and probing space-time quantum foam

106nonenoneBurderi, Luciano; Di Salvo, Tiziana; Riggio, Alessandro; Gambino, Angelo Francesco; Sanna, Andrea; Fiore, Fabrizio; Amarilli, Fabrizio; Amati, Lorenzo; Ambrosino, Filippo; Amelino-Camelia, Giovanni; Anitra, Alessio; Barbera, Marco; Bechini, Michele; Bellutti, Paolo; Bertaccin, Roberto; Bertuccio, Giuseppe; Campana, Riccardo; Cao, Jiewei; Capozziello, Salvatore; Ceraudo, Francesco; Chen, Tianxiang; Cinelli, Marco; Citossi, Marco; Clerici, Aurora; Colagrossi, Andrea; Costa, Enrico; Curzel, Serena; De Laurentis, Mariafelicia; Della Casa, Giovanni; Della Valle, Massimo; Demenev, Evgeny; Del Santo, Melania; Dilillo, Giuseppe; Efremov, Pavel; Evangelista, Yuri; Feroci, Marco; Ferruglio, Chiara; Ferrandi, Fabrizio; Fiorini, Mauro; Fiorito, Michele; Frontera, Filippo; Fuschino, Fabio; Gacnik, Dejan; Galgoczi, Gabor; Gao, Na; Gandola, Massimo; Ghirlanda, Giancarlo; Gamboc, Andreja; Grassi, Marco; Guidorzi, Cristiano; Guzman, Alejandro; Iaria, Rosario; Karlica, Mile; Kostic, Uros; Labanti, Claudio; La Rosa, Giovanni; Lo Cicero, Ugo; Lopez Fernandez, Borja; Lunghi, Paolo; Malcovati, Piero; Maselli, Alessandro; Manca, Arianna; Mele, Filippo; Milankovich, Dorottya; Monge, Angel; Morgante, Gianluca; Nava, Lara; Negri, Barbara; Nogara, Paolo; Ohno, Masanori; Ottolina, Daniele; Pasquale, Andrea; Pal, Andras; Perri, Matteo; Piccinin, Margherita; Piazzolla, Raffaele; Pirrotta, Simone; Pliego-Caballero, Samuel; Prinetto, Jacopo; Pucacco, Giuseppe; Puccetti, Simonetta; Rapisarda, Massimo; Rashevskaya, Irina; Rashevsky, Alexander; Ripa, Jakub; Russo, Francesco; Papitto, Alessandro; Piranomonte, Silvia; Santangelo, Andrea; Scala, Francesca; Sciarrone, Giulia; Selcan, David; Silvestrini, Stefano; Sottile, Giuseppe; Rotovnik, Tomaz; Tenzer, Christoph; Troisi, Ivan; Vacchi, Andrea; Virgilli, Enrico; Werner, Norbert; Wang, Lingjun; Xu, Yupeng; Zampa, Gianluigi; Zampa, Nicola; Zane, Silvia; Zanotti, GiovanniBurderi, Luciano; Di Salvo, Tiziana; Riggio, Alessandro; Gambino, Angelo Francesco; Sanna, Andrea; Fiore, Fabrizio; Amarilli, Fabrizio; Amati, Lorenzo; Ambrosino, Filippo; Amelino-Camelia, Giovanni; Anitra, Alessio; Barbera, Marco; Bechini, Michele; Bellutti, Paolo; Bertaccin, Roberto; Bertuccio, Giuseppe; Campana, Riccardo; Cao, Jiewei; Capozziello, Salvatore; Ceraudo, Francesco; Chen, Tianxiang; Cinelli, Marco; Citossi, Marco; Clerici, Aurora; Colagrossi, Andrea; Costa, Enrico; Curzel, Serena; De Laurentis, Mariafelicia; Della Casa, Giovanni; Della Valle, Massimo; Demenev, Evgeny; Del Santo, Melania; Dilillo, Giuseppe; Efremov, Pavel; Evangelista, Yuri; Feroci, Marco; Ferruglio, Chiara; Ferrandi, Fabrizio; Fiorini, Mauro; Fiorito, Michele; Frontera, Filippo; Fuschino, Fabio; Gacnik, Dejan; Galgoczi, Gabor; Gao, Na; Gandola, Massimo; Ghirlanda, Giancarlo; Gamboc, Andreja; Grassi, Marco; Guidorzi, Cristiano; Guzman, Alejandro; Iaria, Rosario; Karlica, Mile; Kostic, Uros; Labanti, Claudio; La Rosa, Giovanni; Lo Cicero, Ugo; Lopez Fernandez, Borja; Lunghi, Paolo; Malcovati, Piero; Maselli, Alessandro; Manca, Arianna; Mele, Filippo; Milankovich, Dorottya; Monge, Angel; Morgante, Gianluca; Nava, Lara; Negri, Barbara; Nogara, Paolo; Ohno, Masanori; Ottolina, Daniele; Pasquale, Andrea; Pal, Andras; Perri, Matteo; Piccinin, Margherita; Piazzolla, Raffaele; Pirrotta, Simone; Pliego-Caballero, Samuel; Prinetto, Jacopo; Pucacco, Giuseppe; Puccetti, Simonetta; Rapisarda, Massimo; Rashevskaya, Irina; Rashevsky, Alexander; Ripa, Jakub; Russo, Francesco; Papitto, Alessandro; Piranomonte, Silvia; Santangelo, Andrea; Scala, Francesca; Sciarrone, Giulia; Selcan, David; Silvestrini, Stefano; Sottile, Giuseppe; Rotovnik, Tomaz; Tenzer, Christoph; Troisi, Ivan; Vacchi, Andrea; Virgilli, Enrico; Werner, Norbert; Wang, Lingjun; Xu, Yupeng; Zampa, Gianluigi; Zampa, Nicola; Zane, Silvia; Zanotti, Giovann