Response of BC-418 plastic scintillator to low-energy protons

The response of fast plastic scintillators to protons is unknown for energies below approximately 300 keV. The response of BC-418 plastic scintillator to protons from 100 keV to 1 MeV was measured using elastic scattering of neutrons at the University of Kentucky. Protons of precise energies from a Van de Graaff accelerator impinged on a thin LiF target to produce neutrons in narrow energy bands. A coincidence was detected between the recoiling proton in the plastic scintillator and the elastically scattered neutron in a liquid scintillator. The energy of the recoil proton was determined by the elastic scattering kinematics, with the scattered neutron energy precisely determined by time of flight. The results are compared with previous measurements of the response of similar plastic scintillators in the energy region where they overlap.