Calibration of the DAMPE Plastic Scintillator Detector and its on-orbit performance

DArk Matter Particle Explorer (DAMPE) is a space-borne apparatus for detecting the high-energy cosmic-rays like electrons, $\gamma$-rays, protons and heavy-ions. Plastic Scintillator Detector (PSD) is the top-most sub-detector of the DAMPE. The PSD is designed to measure the charge of incident high-energy particles and it also serves as a veto detector for discriminating $\gamma$-rays from charged particles. In this paper, PSD on-orbit calibration procedure is described, which includes five steps of pedestal, dynode correlation, response to minimum-ionizing particles (MIPs), light attenuation function and energy reconstruction. A method for reconstructing the charge of incident high energy cosmic-ray particles is introduced. The detection efficiency of each PSD strip is verified to be above 99.5%, the total efficiency of the PSD for charged particles is above 99.99%.