Jiawen Zhang

A method for calibrating PMTs in T0 system for beam test

In order to study the performance of MRPC, which will be used for the upgrade of the Endcap TOF in BES III, a T0 system is composed of high speed response PMTs H6533 coupling with BC420 plastic scintillators. Because the T0 system should offer a toughly strict timing start, the high precision electronics based on VME system were used to test the SPS (single-photoelectron spectrum) of H6533 PMT. A suitable operation voltage for optimal performance is confirmed by researching the dependence relationship between the PMT gain and energy resolution of SPS (single-photoelectron spectrum). At the end, the timing resolution of this type of T0 system was 41.6 ps in the cosmic ray test and 39.1 ps in the proto beam test.

An improved underground cosmic-ray detector made of RPCs

In order to suppress muon-induced background, veto detector is very important, even if the particle physics experiments are deployed underground. Owing to its high efficiency, low cost and low sensitivity to environmental gamma-rays, resistive plate chamber (RPC) is a good candidate for large-area underground cosmic-ray detectors. Based on the experiences and lessons from the RPC veto detector in Daya Bay neutrino experiment, an improved design has been proposed considering the extremely low muon flux, which results in underestimation of RPC layer detection efficiency in self-calibration. Additionally, allowing for the studies of 9Li/8He and fast neutrons, the tracking ability has been considered in design. Finally, an improved design of an RPC underground cosmic-ray detector has been achieved.