DETECTION EFFICIENCY OF A PLASTIC SCINTILLATOR FOR 10-70 MEV NEUTRONS

The neutron detection efficiency of a plastic scintillator 30.5 cm long and 12.7 cm in dia. has been measured for neutron energies from about 10-70 MeV. These were obtained by scattering a 193 MeV neutron beam from a liquid hydrogen target. A telescope selected protons from the n-p scattering which then determined the energy and flux of neutrons in the conjugate solid angle. A known fraction of this flux was intercepted by the neutron detector and the efficiency was thus determined. For an electron threshold near 1 MeV the efficiency is nearly constant from 20-50 MeV, then it decreases slowly with increasing neutron energy. As expected thresholds two and four times larger decrease the efficiency, particularly at low energy. © 1968.