A new 64-channel area detector for neutrons and gamma rays

The multi-channel photomultiplier (Philips XP1702) can be utilized as a hig h resolution area detector for thermal neutrons and high energy gamma rays. This detector type is needed e.g. for special neutron scattering experimen ts and for the PET method applied to small animals. In various test measure ments this will be demonstrated by coupling suitable scintillators (NaI, EG O, and (LiI)-Li-6 single crystals and Li-6-glass) and dispersers to the pho tocathode and by feeding the 64 output signals of the PM into a resistor ne twork via voltage-to-current converters. The final interpolated position pe r event is determined by pulse height division of the four amplified signal s taken from the corners of the network. Experimental results concerning th e achievable spatial resolution, the homogeneity and the linearity of the d etector response and of the quantum efficiencies will be presented. Light e xperiments with well collimated pulsed rays and with beams of different spo t sizes at the photocathode are helpful to explain the measured properties of this new neutron and gamma ray detector.