Fast neutrons from thick deuterium target irradiated by 15.8 MeV protons and 14.1 MeV deuterons

The energy spectra of neutrons emitted by a thick deuterium target at 0° angle, irradiated by a beam of 15.8 MeV protons and 14.1 MeV deuterons were measured in an open geometry with a stilbene scintillator and with a two-dimensional n-gamma discrimination technique. The evaluated spectral yields were compared with those of p+Be and d+Be reactions at relevant energies. This comparison shows that the D-target spectra are substantially harder having small relative contribution of low-energy neutrons, which makes these reactions useful as intense neutron sources for biomedical and analytical purposes. The total neutron yield from the d+D reaction is in good agreement with values calculated from published differential cross-section data. The p+D reaction seems to be the most effective fast neutron source, based on low-energy (E<40 MeV) cyclotrons.