A study of a large plastic scintillation fast neutron detector

For the purpose of studying some nuclear reactions in few-nucleon systems in the hundred MeV region, a large plastic scintillation detector (50 cm X 10 cm X 10 cm) equipped with two photomultipliers and a system of hodoscopes was constructed. Its principal characteristics and the neutron detection efficiency at about 20 MeV have been studied with neutrons produced by the 2H(d,n)3He reaction for which the energy Rsub(n) and the scattering angle thetasub(n) have been precisely defined by those of 3He in coincidence. The efficiency is about 25% +- 2% with the threshold energy of 1 MeV (UEQ). The discrimination n-γ was made by the difference of their times of flight. The reduced time of flight resolution is in the order of 0.8 ns in which the fluctuation of the correlated 3He time of flight is included. (Auth.)