Simulation and photoelectron track reconstruction of soft X-ray polarimeter

The soft X-ray polarimeter (SXP) is a detector with a wide energy range, large area, and large field of view. A SXP will be mounted on the Chinese Space Station and will mainly focus on detecting the polarization of transient soft X-ray (2–10 keV) sources, especially gamma-ray bursts (GRBs). In this work, a polarimeter detector unit is taken as an example, and Geant4 and Garfield++ software are used to simulate the detection efficiency and track production. An improved track reconstruction algorithm is proposed and used to reconstruct two-dimensional images of the tracks. In this method, the initial emission angle of photoelectrons is reconstructed from the initial part of the track by shortening or extending the initial part of the track until the remaining track is straight, and the number of pixels is within an adjustable threshold. The modulation factor of the photoelectronic tracks after reconstruction reaches approximately 57% in the photon energy range of 7–10 keV.