Title: Design study of quasi-monoenergetic neutron source based on $^9$Be(p,n) reaction using GEANT4
The design study of quasi-monoenergetic neutron source based on 9Be(p,n) reaction was conducted with GEANT4. The main purpose is to optimize the thickness of Be-target and proton absorber and the position of the sample from the Be-target. In particular, the minimum thickness for stopping all protons after proton absorber (graphite or tungsten) was calculated and the effect of proton absorber in the neutron yield was simulated. In order to find out the optimum thickness of the Be-target, we simulated the neutron energy spectra for the thickness of the Be-target changing from 0.5 mm to 3.0 mm with various proton energies (25, 30, 35, 40, and 45 MeV). We fitted neutron energy spectra using the Gaussian fit in the quasi-monoenergetic neutron energy region to find out the FWHM value. We defined a new factor F_tar to determine the optimal Be-target thickness for various energies of proton. Also, we determined the optimal distance between the Be-target and the sample by using the FWHM for the neutron energy spectra. The results of this study can be used for experiments using quasi-monoenergetic neutron source in Korean Institute of Radiological and Medical Sciences (KIRAMS).
Thesis Advisor: Prof. Guinyun Kim