Calorimeter calibration of the ComPol CubeSat gamma-ray polarimeter

ComPol is a proposed CubeSat mission dedicated to long-term study of gamma-ray polarisation of astrophysical objects. Besides spectral and timing measurements, polarisation analysis can be a powerful tool in constraining current models of the geometry, magnetic field structure and acceleration mechanisms of different astrophysical sources. The ComPol payload is a Compton telescope optimised for polarimetry and consists of a 2 layer stacked detector configuration. The top layer, the scatterer, is a Silicon Drift Detector matrix developed by the Max Planck Institute for Physics and Politecnico di Milano. The second layer is a calorimeter consisting of a CeBr3 scintillator read-out by silicon photo-multipliers developed at CEA Saclay. This paper presents the results of the prototype calorimeter calibration campaign, executed in March 2022 at IJCLab Orsay and simulations of the expected performance of the polarimeter using updated performance figures of the detectors.