Thick and Thin Target ⁷Li(p,n)⁷Be Neutron Spectra Below the Three-Body Breakup Reaction Threshold

Recently, we measured the ⁷⁰Zn(n,γ)⁷¹Zn^m activation cross sections using the ⁷Li(p,n)⁷Be neutron source for 2.0 MeV < E_p < 3.7 MeV. Since the time-of-flight and multiple foil activation techniques cannot be applied due to the continuous beam structure and weak neutron flux at the facility, we have to rely on calculated neutron energy spectra for data reduction procedure. There are existing Monte Carlo–based codes such as Protons In Neutrons Out (PINO) and SimLiT for calculation of ⁷Li(p,n)⁷Be neutron source spectra at these energies. However, these two codes predicted different neutron spectra at these energy regions. We therefore decided to study the thick and thin target ⁷Li(p,n)⁷Be neutron spectra from the reaction threshold to the three-body breakup threshold by deterministic calculation. The predicted neutron spectra near threshold were validated by experimental neutron spectra. Our neutron spectra were compared with those predicted by PINO and SimLiT. Our neutron spectra at E_p = 2.8 and 3.5 MeV agree perfectly with those predicted by SimLiT but not with those predicted by PINO.