SDD Analog Readout System for the ComPol CubeSat Compton Polarimeter

Astronomical X-ray polarimetry is a powerful tool to extract information from hard X-rays spectrum of celestial bodies. In this context, the ComPol project aims to fly a Compton polarimeter in a CubeSat to investigate the emissions of the binary black hole (BBH) system Cygnus X-1. Based on Compton events detection, the CubeSat is featured by two detection systems: 1) a Silicon Drift Detector (SDD) matrix employed as scatterer and 2) a scintillator read by Silicon Photon Multiplier (SiPM) array to absorb the scattered photons. This paper focuses on the development of the first detection system for the reconstruction of Compton events. The readout electronic chain is composed of two 7-pixel SDD matrices, CUBE preamplifiers and SFERA ASIC Analog Pulse Processor (APP) handled by FPGA technology for its control and data flow management. This paper presents this readout system, composed by two boards: one housing SFERA ASIC, which includes an on-chip ADC, the other which includes the SDD matrix and the preamplifiers. In this manuscript, the test results performed with the pre-prototype system devised in the first phase of the project to characterize the SDD module and to evaluate the SFERA internal ADC performances are reported together with the ones performed with the prototype system.