A Method of Alignment of the Plastic Scintillator Detector of DAMPE

TL;DR

This paper presents a novel alignment method for the DAMPE's Plastic Scintillator Detector, improving charge resolution and gamma-ray identification by correcting for shifts and rotations of detector bars.

Contribution

The paper introduces a new alignment technique for the PSD of DAMPE that accurately determines and corrects for shifts and rotations of detector bars using energy spectra analysis.

Findings

Alignment shifts are about 1mm on average.

Rotation corrections are approximately 0.0015 radians.

Charge resolution improves from 4% to 8%.

Abstract

The Plastic Scintillator Detector (PSD) of the DArk Matter Particle Explorer (DAMPE) is designed to measure cosmic ray charge (Z) and to act as a veto detector for gamma-ray identification. In order to fully exploit the charge identification potential of the PSD and to enhance its capability to identify the gamma ray events, we develop a PSD detector alignment method. The path length of a given track in the volume of a PSD bar is derived taking into account the shift and rotation alignment corrections. By examining energy spectra of corner-passing events and fully contained events, position shifts and rotations of all PSD bars are obtained, and found to be on average about 1mm and 0.0015 radian respectively. To validate the alignment method, we introduce the artificial shifts and rotations of PSD bars in the detector simulation. These shift and rotation parameters can be recovered successfully by the alignment procedure. As a result of the PSD alignment procedure, the charge resolution of the PSD is improved from $4\%$ to $8\%$ depending on the nuclei.