The cosmic ray test of MRPCs for the BESIII ETOF upgrade

In order to improve the particle identification capability of endcap time-of-flight (ETOF) at Beijing Spectrometer III, it is proposed to upgrade current ETOF detector with multi-gap resistive plate chamber (MRPC) technology aiming at extending ETOF overall time resolution to be 80–100 ps for \(\pi \)’s. The new ETOF system including MRPC detectors, front end electronics, CLOCK module, fast control boards and time-to-digital conversion modules, was built up and underwent 3-month cosmic ray test. The main purposes of the cosmic ray test are examining the construction quality of the system, testing the joint operation of all instruments and guaranteeing the system performance. The results show that MRPC time resolution is better than 80 ps, average efficiency is about 98.5 % and the noise rate of strip is 0.2 Hz/\(\mathrm{cm}^{2}\) at the threshold range for normal operation. These results indicate that the entire ETOF system would work well and satisfy the requirements of upgrade.