A detector system for angular correlation measurements by using parallel plate avalanche counters

A detector system for measurement of angular correlations in binary fission reactions, which are induced by 1 GeV protons, is described. A new type of parallel plate avalanche counsisting of two grids delivers the start signal for the time-of-flight measurement for the correlated fragments. With this detector we obtained an energy loss of 7.8 MeV and an intrinsic time resolution of τ=320 ps for spontaneous fission fragments from a 252Cf source. A large area position-sensitive parallel plate avalanche counter (3.5×18 cm2) with delay-line read-out measures the coordinate of the complementary fragment within an accuracy of 4.3 mm (corresponding to 1.3°). The spatial resolution has been measured for α-particles and fission fragments under different conditions. The reliability of the developed detector system was checked experimentally with U and Bi targets, which were bombarded with 1 GeV protons.