Plastic scintillation detectors for precision Time-of-Flight measurements of relativistic heavy ions

Plastic scintillation detectors for Time-of-Flight (TOF) measurements are almost essential for event-by event identification of relativistic rare isotopes. In this work, a pair of plastic scintillation detectors of dimensions 50 x 50 x 3(t) mm(3) and 80 x 100 x 3(t) mm(3) have been set up at the External Target Facility (ETF), Institute of Modern Physics (IMP). Their time, energy and position responses are measured with the O-18 primary beam at 400 MeV/nucleon. After off-line corrections for walk effect and position, the time resolutions of the two detectors are determined to be 27 ps (sigma) and 36 ps (sigma), respectively. Both detectors have nearly the same energy resolution of 3.1% (sigma) and position resolution of about 3.4 mm (sigma). The detectors have been used successfully in nuclear reaction cross section measurements, and will be be employed for upgrading the RIBLL2 beam line at IMP as well as for the high energy branch at HIAF.