Development of a Time-of-Flight detector for the Rare-RI Ring project at RIKEN

We have tested the timing properties of several thin plastic scintillators (10-500 μm) designed for the Rare-RI Ring project at the RI Beam factory. The experiments were performed at the heavy-ion synchrotron facility, HIMAC (Heavy Ion Medical Accelerator in Chiba), using a Xe beam with an energy of 200 MeV/nucleon. The scintillation light was read out by fast-timing photomultipliers through standard fishtail-shaped light guides. The resultant timing resolutions reached a few tens of picoseconds, which satisfied our requirement for the project. We also measured charge-state distributions for Xe and Fe ions penetrating carbon foils of 10-500 μg/cm thickness. The results were compared with a theoretical model calculation for charge-state evolution.