Thick target neutron yields for the Li(p,n)Be reaction near threshold

Transportable accelerator sources of epithermal neutrons are crucial for the development of hospital-based boron neutron capture therapy (BNCT) as a treatment modality for brain cancers. One method for producing such epithermal neutrons is near-threshold (p,n) reactions as studied by our group, as well as several other investigators. As part of this e€ort, we have developed accurate methods for computing the angular distributions and energy spectra of neutrons from thick targets using the Li(p,n)Be reaction near threshold. Neutron yields are calculated for lithium metal as well as several lithium compounds of low molecular weight. The calculational method is discussed, with emphasis on the improvements over previously published methods. Neutron energy spectra, angular distributions, and total yields for proton beam energies up to 120 keV above threshold are presented. A method is also demonstrated for calculating neutron yields for targets that are not suciently thick to slow protons past the reaction threshold. Ó 1999 Elsevier Science B.V. All rights reserved. PACS: 29.25.Dz; 25.40.Qa; 27.20.+n