Abstract
The energy spectra of secondary neutrons produced when bremsstrahlung of end-point energy in the range 10-30 MeV is incident on oxygen, carbon and nitrogen have been calculated. Photonuclear reactions of the type ( gamma ,n) and ( gamma ,pn) have been included. The respective contributions of various nuclear reactions have been adjusted using the published values of experimentally determined cross-sections, or branching-ratios, where these are available. Where no such information exists in the literature, the values have been empirically estimated. Agreement has been obtained between the calculated photoneutron spectra from C, N and O at various nuclear reactions have been adjusted using the published values of experimentally determined cross-sections, or branching-ratios, where these are available. Where no such information exists in the literature, the values have been empirically estimated. Agreement has been obtained between the calculated photoneutron spectra from C, N and O at various energies and the available experimentally-measured spectra. The photoneutron spectra from C, N and O have been combined in the right proportion (C5H40O18N) to compute the spectra of secondary neutrons from tissue irradiated with bremsstrahlung of end-point energy from 10-30 MeV. Mean neutron energies and kerma factors for these spectra have been calculated.