Scintillator tile batch test of CEPC AHCAL

Abstract

Hadron calorimeter (HCAL) is an essential sub-detector of the baseline detector system for Circular Electron Positron Collider (CEPC). We plan to build an Analog Hadron CALorimeter (AHCAL) prototype based on the Particle Flow Algorithm (PFA). The AHCAL of CEPC uses steel as the absorber and scintillator tiles read out by Silicon Photo-Multipliers (SiPMs) as the sensitive medium. The energy linearity and resolution of the calorimeter depend on the light yield uniformity of the sensitive medium. It is essential to qualify the entire detector production in order to select scintillator tiles with the uniformity of light yield within 10%. An automated batch test platform has been designed with 144 channels and an automated 3D servo motor. The paper summarizes the tests performed on more than 15000 scintillator tiles, and the SiPMs work at 59 V (overvoltage: 5 V). The measured light yield, corrected for the set-up response non-uniformity, is around 12.9 p.e. About 91.6% of scintillators (14219 pieces) are qualified within 10% of the light yield window.