Measurement of response functions of organic liquid scintillator for neutron energy range up to 390 MeV

The neutron response functions of 12.7 cm diameter by 12.7 cm long NE213 organic liquid scintillator have been measured in the energy range up to 390 MeV at the Research Center for Nuclear Physics (RCNP) of Osaka University. The continuous energy neutrons were produced by the 392 MeV proton bombardment on a 20-cm thick aluminum target and the response functions of the time-of-flight (TOF)-gated monoenergetic neutrons in a wide energy range up to 390 MeV were simultaneously measured. The quasi-monoenergetic neutrons were also produced via 7Li(p,n)7Be reaction by the 392-MeV proton beam bombardment on a 1.0-cm thick 7Li target, and the TOF-gated 388-MeV peak neutrons were used to obtain the response function at this energy. The measured results show that the response functions for monoenergetic neutrons below 100 MeV have a recoil proton plateau and an edge around the maximum light output which increases with increasing neutron energy, while on the other hand, for energies above 100 MeV, the plateau and the edge become unclear because the proton range starts to exceed the detector size allowing protons to escape.