particle accelerator Hiroshima University Radiobiological Research Accelerator A neutron generator at the Research Institute for Radiation Biology and Medicine, Hiroshima University (RIRBM). Monoenergetic neutrons of which energy is less than 1.3 MeV are generated by the 7Li(p,n)7 Be reaction at proton energies up to 3 MeV. HIRRAC HIRRAC The samples were irradiated with fast neutrons at the HIRRAC.