Development of a quasi-monoenergetic neutron field and measurements of the response function of an organic liquid scintillator for the neutron energy range from 66 to 206 MeV

A quasi-monoenergetic neutron field was developed using a thin 7Li target bombarded by protons in the energy range from 70 to 210 MeV at the RIKEN ring cyclotron facility. The neutron energy spectra were measured with an NE213 organic liquid scintillator using the TOF method. The absolute peak neutron yields were obtained by measurements of 478 keV γ-rays from 7Be nuclei produced in a 7Li target through the 7Li( p,n)7Be (g.s.+0.429 MeV) reaction. the neutron field, the absolute values of the neutron response functions of a 12.7 cm diameter by 12.7 cm long NE213 organic liquid scintillator were measured, and were compared with calculations using a Monte Carlo code developed by Cecil et al. The measured response functions without any wall-effect events were also obtained, and compared with calcualtions using a modified Monte Carlo code. Comparisons between a measurement and a calculation both with and without any wall-effect events gave a good agreement.