Neutron spectra produced by 30, 35 and 40 MeV proton beams at KIRAMS MC-50 cyclotron with a thick beryllium target

Abstract Neutrons over a wide range of energies are produced by bombarding a 1.05 cm thick beryllium target with protons of different energies delivered by the MC-50 Cyclotron of the Korea Institute of Radiological Medical Sciences (KIRAMS). The neutron flux Φ ( E n ) versus neutron energy E n , produced by protons of 30, 35, and 40 MeV energies, was obtained by using the GEANT4 code with a data-based hadronic model. For the experimental validation of the simulated neutron spectra, a number of pure aluminum and iron oxide samples were irradiated with the neutrons produced by 30, 35, and 40 MeV protons at 20 μ A beam current. The gamma-ray activities of 24 Na and 56 Mn produced, respectively, through 27 Al(n, α ) 24 Na and 56 Fe(n,p) 56 Mn reactions were measured by a HPGe detector. The neutron flux Φ ( E n ) at each neutron energy from the simulation was multiplied with the evaluated cross-sections σ ( E n ) of the respective nuclear reaction, and the summation ∑ Φ ( E n ) σ ( E n ) was calculated over the neutron spectrum for each proton energy of 30, 35, and 40 MeV. The measured gamma-ray activities of 24 Na and 56 Mn were found in good agreement with the activities estimated by using the summed values of ∑ Φ ( E n ) σ ( E n ) along with other parameters in a neutron activation method.