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arXiv · 2508.00642

Prototype Development and Calibration of the CUbesat Solar Polarimeter (CUSP)

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

The space-based CUbesat Solar Polarimeter (CUSP) mission aims to measure the linear polarization of solar flares in the hard X-ray band by means of a Compton scattering polarimeter. CUSP will allow to study the magnetic reconnection and particle acceleration in the flaring magnetic structures of our star with its unprecedented sensitivity to solar flare polarization. CUSP is a project in the framework of the Alcor Program of the Italian Space Agency aimed to develop new CubeSat missions. It has been proposed as a constellation of a two Cubesat mission to monitor the Sun for Space Weather, and will proceed with a single-satellite asset in its baseline implementation. In the frame of CUSP's Phase B study, that started in December 2024 for a 1-year period, we present the development status of this dual-phase polarimeter. Preliminary laboratory results using two chains of acquisition will be discussed. The first chain of acquisition, based on the Hamamatsu R7600 multi-anode photomultiplier tubes coupled to plastic scintillator bars and read out by the MAROC-3A ASIC, is used to detect the Compton scattering of incoming photons. On the other hand, GAGG crystals coupled to avalanche photo-diodes with a readout based on the SKIROC-2A ASIC are used to absorb the scattered photons. By reconstructing the azimuthal scattering direction for many incoming photons, one can infer the linear polarization degree and angle of the source. We will discuss the calibration results obtained with our prototype detector by using well-known radioactive isotopes, allowing us to assess the performances of our detector over the full 25-100 keV energy range.

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Nicolas De Angelis, Abhay Kumar, Sergio Fabiani, Ettore Del Monte, Enrico Costa, Giovanni Lombardi, Paolo Soffitta, Andrea Alimenti, Riccardo Campana, Mauro Centrone, Giovanni De Cesare, Sergio Di Cosimo, Giuseppe Di Persio, Alessandro Lacerenza, Pasqualino Loffredo, Gabriele Minervini, Fabio Muleri, Paolo Romano, Alda Rubini, Emanuele Scalise, Enrico Silva, Davide Albanesi, Ilaria Baffo, Daniele Brienza, Valerio Campamaggiore, Giovanni Cucinella, Andrea Curatolo, Giulia de Iulis, Andrea Del Re, Vito Di Bari, Simone Di Filippo, Immacolata Donnarumma, Pierluigi Fanelli, Nicolas Gagliardi, Paolo Leonetti, Matteo Merge, Dario Modenini, Andrea Negri, Daniele Pecorella, Massimo Perelli, Alice Ponti, Francesca Sbop, Paolo Tortora, Alessandro Turchi, Valerio Vagelli, Emanuele Zaccagnino, Alessandro Zambardi, Costantino Zazza. 2025-08-01. Prototype Development and Calibration of the CUbesat Solar Polarimeter (CUSP). https://doi.org/10.1117/12.3064407

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