The use of the thin plastic scintillator focused by using concave ellipsoidal mirror in heavy ion TOF

The performances of a simple timing detector consisting of a thin plastic scintillator foil and an ellipsoidal mirror made of aluminium are investigated in intermediate energy heavy ion time-of-flight research. An intrinsic time resolution of about 140 ps has been measured for 25 MeV/u 40Ar ions passing through 2.06 mg/cm2 NE102A foil. Detection efficiency and light collection have been investigated. The dependence of the time resolution on the fluctuation of light yield has been caculated by a Monte Carlo method.