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, 20 cm diameter, was made in the middle of the disc in order to allow the beam passage through the detector when it is positioned at very forward or backward angles. The originality of the detector consists of the simultaneous use of four very compact central Photo Multiplier Tubes (PMT) and eight peripheral PMT’s in order to retrieve the hitting point of the charged particle onto the disc surface with a space resolution of ± 3 cm. The original method has been developed by using polar coordinates, in order to retrieve the hitting point via the time-of-flight information (TOF) from 3 or 4 nearest PMT’s only, including at least one cental PMT.
V. Bellini, F. Palazzolo, A. Scirè, M. L. Sperduto, S. Albergo, G. Poli, R. Potenza, C. Randieri, V. Russo, M. C. Sutera, M. Capogni, C. Schaerf, A. D’Angelo, D. Moricciani, A. V. Kuznetsov, B. Girolami, F. Ghio
INFN – LNS Università degli Studi di Catania