  The CSR External-target Experiment (CEE) will be the first large-scale
nuclear physics experiment device at the Cooling Storage Ring (CSR) of the
Heavy-Ion Research Facility in Lanzhou (HIRFL) in China. A new T0 detector has
been proposed to measure the multiplicity, angular distribution and timing
information of charged particles produced in heavy-ion collisions at the target
region. Multi-gap resistive plate chamber (MRPC) technology was chosen as part
of the construction of the T0 detector, which provides precision event
collision times (T0) and collision geometry information. The prototype was
tested with hadron and heavy-ion beams to study its performance. By comparing
the experimental results with a Monte Carlo simulation, the time resolution of
the MRPCs are found to be $\sim$ 50 ps or better. The timing performance of the
T0 detector, including both detector and readout electronics, we found to
fulfil the requirements of the CEE.
