Design and performance testing of a T0 detector for the CSR External-target Experiment

The Cooling Storage Ring External-target Experiment at the Heavy Ion Research Facility in Lanzhou, China, is a multi-purpose nuclear physics experimental device to operate in the Giga electron-volt (GeV) energy range. The time-of-flight (TOF) system is critical for identifying charged particles in the GeV energy range. In the Experiment spectrometer, the TOF system consists of three parts: T0, internal TOF, and external TOF. The T0 detector provides a high-precision start time for the TOF system by measuring the crossing time of the heavy ion beam. This study details the design, performance simulation, and performance testing of the T0 detector. The simulation results and heavy-ion beam test show that the T0 detector prototype has an excellent time resolution, which is better than 30 ps, and fulfills the requirements of the CEE.