Study of MRPC technology for BESIII endcap-TOF upgrade

Abstract

In order to improve the charged particle identification capability, end-cap time-of-flight (ETOF) detector of the Beijing Spectrometer (BESIII) has been upgraded with multi-gap resistive plate chamber (MRPC) technology, aiming at an overall time resolution of 80 ps for minimum-ionization particles to extend the K/ $$\pi $$ separation (2 $$\sigma $$ ) momentum range to 1.4 GeV/c. The previous version of ETOF in BESIII consisted of plastic scintillators. The multi-hit events distort both shape and amplitude of the output signals. MRPC technique was chosen for the BESIII ETOF upgrade as it provides high time resolution and high detection efficiency, is of relatively low cost and is insensitive to neutral particles. Most importantly, the fine segmentation of the MRPC readout stripes can suppress multi-hit events effectively. The final design of MRPC module for ETOF is characterized by double-stack (2 $$\times $$ 6) structure, dual-end readout mode and precision electronics. To batch-produce and test these MRPC modules, a series of tools and production procedures as well as related performance simulation and test methods were developed. Results showed that each MRPC module’s intrinsic time resolution (including the electronics contribution) is around 50 ps and the efficiency is better than 97%. The overall performance of the upgraded ETOF is better than the designed index. The new ETOF has been successfully installed at BESIII and run in 2016.