Neutron induced charged particle spectra and kerma from 25 to 60 MeV

Neutron beams in the tens of MeV range are widely used in biomedical applications. At these energies the reaction channels open to charged particles increase compared to the situation prevailing below about 15 MeV. An extensive program to measure charged particle products on tissue-resident elements (H, O, C, and N) has been carried out at Crocker Nuclear Laboratory. The particles detected include protons, deuterons, tritons, helium-3 and alphas, measured over a wide angular range for neutron energies of 27.4, 39.7, and 60.7 MeV. Good agreement is found in comparison with charge symmetric proton-induced energy spectra (such as in (p,d) vs. (n,d)). Kerma have been obtained at the three energies for each nucleus including elastic recoil contributions. The use of sum rules to obtain the missing (non-elastic) contribution from heavier fragments is examined. These experimental kerma values are found to be considerably different than predictions by several authors. Recent calculations by Brenner and by Dimbylow are in better agreement with the experimental kerma. (author)