In orbit background for hard X-ray CubeSat polarimeters: case study of the CUSP mission in low-earth orbit

Abhay Kumar; Giovanni Lombardi; Riccardo Campana; Giovanni De Cesare; Sergio Fabiani; Ettore Del Monte; Andrea Alimenti; Enrico Costa; Mauro Centrone; Nicolas De Angelis; Sergio Di Cosimo; Giuseppe Di Persio; Pasqualino Loffredo; Gabriele Minervini; Fabio Muleri; Paolo Romano; Alda Rubini; Emanuele Scalise; Enrico Silva; Paolo Soffitta; Giovanni Cucinella; Vito Di Bari; Simone Di Filippo; Andrea Negri; Massimo Perelli; Dario Modenini; Andrea Curatolo; Nicolas Gagliardi; Daniele Pecorella; Alice Ponti; Paolo Tortora; Andrea Del Re; Davide Albanesi; Valerio Campamaggiore; Giulia de Iulis; Adam Ebrahim; Paolo Leonetti; Marco Schepis; Alessandro Zambardi; Ilaria Baffo; Pierluigi Fanelli; Costantino Zazza; Valerio Vagelli; Daniele Brienza; Immacolata Donnarumma; Matteo Merge; Emanuele Zaccagnino; Alessandro Turchi

arXiv · 2608.01524

In orbit background for hard X-ray CubeSat polarimeters: case study of the CUSP mission in low-earth orbit

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Abstract

The CUbesat Solar Polarimeter (CUSP) project aims to measure the linear polarization of solar flares in the 25 - 100 keV hard X-ray band using a Compton scattering polarimeter. CUSP is a project in the framework of the Alcor Program of the Italian Space Agency aimed to develop innovative CubeSat technologies and missions. As part of CUSPs Phase B study, initiated in December 2024 and closed on July 2nd, 2026, estimating the in orbit background to optimize the signal-to-background ratio was one of the key objectives. In low-Earth orbit, the instrument is exposed to cosmic and albedo X-ray backgrounds, charged particles, and secondary radiation from the spacecraft and atmosphere. Simulating these contributions enables optimization of detector geometry and shielding to maximize signal-to-noise performance. We present initial in orbit background estimates for CUSP using a Geant4-based simulator. A detailed mass model of the CUSP has been implemented to simulate background components and estimate the background count rate in the CUSP orbit.

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Abhay Kumar, Giovanni Lombardi, Riccardo Campana, Giovanni De Cesare, Sergio Fabiani, Ettore Del Monte, Andrea Alimenti, Enrico Costa, Mauro Centrone, Nicolas De Angelis, Sergio Di Cosimo, Giuseppe Di Persio, Pasqualino Loffredo, Gabriele Minervini, Fabio Muleri, Paolo Romano, Alda Rubini, Emanuele Scalise, Enrico Silva, Paolo Soffitta, Giovanni Cucinella, Vito Di Bari, Simone Di Filippo, Andrea Negri, Massimo Perelli, Dario Modenini, Andrea Curatolo, Nicolas Gagliardi, Daniele Pecorella, Alice Ponti, Paolo Tortora, Andrea Del Re, Davide Albanesi, Valerio Campamaggiore, Giulia de Iulis, Adam Ebrahim, Paolo Leonetti, Marco Schepis, Alessandro Zambardi, Ilaria Baffo, Pierluigi Fanelli, Costantino Zazza, Valerio Vagelli, Daniele Brienza, Immacolata Donnarumma, Matteo Merge, Emanuele Zaccagnino, Alessandro Turchi. 2026-08-02. In orbit background for hard X-ray CubeSat polarimeters: case study of the CUSP mission in low-earth orbit. https://arxiv.org/abs/2608.01524

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