Position sensitive disc for charged particle detection

A plastic scintillating disc (NE102, 3 cm thick, 1 m diameter) has been designed for detecting charged pions in nuclear reactions at intermediate energy. A hole of 20 cm diameter was made in the middle of the disc in order to allow for the beam passage through the detector. The originality of the detector consists of the simultaneous use of four very compact central Photo Multiplier Tubes (PMT) and eight peripheral PMTs in order to retrieve the hitting point of a charged particle onto the disc surface with a space resolution of ±3 cm. The original method has been developed by using polar coordinates and only the Time-Of-Flight information (TOF) from three or four nearest PMTs, including at least one central PMT.