Stripping-theory analysis of thick-target neutron production for D+Be (and tissue dose calculation)

Publisher Website
Google Scholar
Abstract
The Serber theory for deuteron (D+) stripping is employed to predict the shape of the neutron energy spectrum produced by 35 MeV D+ on a thick Be target. The observation that the maximum of the neutron energy spectrum (at 0.degree. C relative to the D+ beam direction) occurs at .apprx. 0.4 Ed, where Ed is the incident deuteron energy, is explained reasonably well by the calculations. The explanation stems from the fact that the stripping theory for thin targets predicts a narrow maximum at 0.5 Ed, and thick target effects shift the maximum downward in energy to .apprx. 0.4 Ed. A number of recent spectral measurements are in agreement with these predictions for a wide range of target materials and incident Ed. The application of this theory also accounts for the previously observed Ed2.99 dependence of the absorbed dose in tumor tissue, per unit charge of D+ ions on target, in the direction of the incident beam. This approximate Ed3 dependence is a characteristic property of deuteron stripping in a thick target and follows directly from the calculations that predict the neutron energy spectrum.