  The cooling storage ring (CSR) external-target experiment (CEE) is a
spectrometer running at the Heavy Ion Research Facility (HIRFL) at Lanzhou. The
CEE is the first large-scale nuclear physics experimental device by China to
operate in the fixed-target mode with an energy of 1 GeV. The purpose of the
CEE is to study the properties of dense nuclear matter. CEE uses a multi-gap
resistive plate chamber (MRPC) as its internal time-of-flight (iTOF) detector
for the identification of final-state particles. An iTOF-MRPC prototype with 24
gaps was designed to meet the requirements of CEE, and the readout electronics
of the prototype use the FPGA-based time digitization technology. Using cosmic
ray tests, the time resolution of the iTOF prototype was found to be
approximately 30 ps. In order to further understand how to improve the time
resolution of MRPC, ANSYS HFSS was used to simulate the signal transmission
process in MRPC. The main factors affecting the timing performance of the MRPC
and, accordingly, the optimization scheme are presented.
