LOW-PRESSURE MWPC SYSTEM FOR THE DETECTION OF ALPHA-PARTICLESAND FISSION FRAGMENTS

A low-pressure, position-sensitive, multi-wire proportional chamber (LPMWPC) system with an active area 12×12 cm2 for the detection of heavy nuclear fragments, has been developed for use in tagged photon beam experiments. The LPMWPC system can be operated in single as well as double step operational modes. In the case of double step operational mode with a high gas amplification factor, signals from α-particles reside well above the electronic noise. Typical energy loss spectra of alpha particles and fission fragments (FF) obtained from a 252Cf source are shown and discussed. The pulse height distributions of α-particles have a Landau distribution shape, while the pulse height distribution of FFs differs from Gaussian shape. It has long tails at both low- and high- energy sides. The average pulse height ratio of alpha particles and FF's is close to the theoretical value and amounts to about 1/80.