A low cost 2/3 of 4π detector for the study of Ps decay

A large area low-cost detector for detailed studies of ortho-Positronium formation and decay is being designed. The detector will be made of four modules each consisting of a thin slab of YAP(Ce) scintillator read out by a multi-anode flat panel photomultiplier tube. The proposed configuration will provide a position sensitive detector capable of recording, on an event-by-event basis, both the 2 gamma and the 3 gamma decay channels, for immediate information on the 2 gamma/3 gamma ratio. It will as well provide a 3D density distribution of the decay vertexes, thus enabling angular and velocity distribution measurements. In this paper we present the results of measurements performed on one module of the detector using conventional electronics, as well as Monte Carlo simulations on the performances of the system. Using a series of laboratory gamma sources we deduced values of energy and spatial resolution.