Performance of the front-end trigger detector for the High-energy Proton Beam Experimental Station (HPES) at CSNS-II

Abstract

This study presents a front-end trigger detector for the High-energy Proton Beam Experimental Station (HPES) at the second phase of the China Spallation Neutron Source (CSNS-II). The detector adopts a compact architecture based on plastic scintillator fiber arrays coupled to photomultiplier tubes. Its timing performance was thoroughly evaluated through a series of rigorous tests using picosecond lasers, radioactive sources, cosmic ray muons, muon beams, and pion beams. Experimental results show that the system achieves an intrinsic time resolution of 210 ± 2 ps and maintains a resolution below 900 ps under realistic particle environments and high-flux beam conditions. This work provides substantial experimental support for the detector's performance, and the detector meets the HPES requirement of < 1 ns time resolution.