Comparison of thick-target (alpha,n) yield calculation codes

Neutron production yields and energy distributions from (α,n) reactions in light elements were calculated using 3 different codes (SOURCES, NEDIS and USD) and compared with the existing experimental data in the 3.5-10 MeV alpha energy range. SOURCES and NEDIS display an agreement between calculated and measured yields in the decay series of ²³⁵U, ²³⁸U and ²³²Th within 10% for most materials. The discrepancy increases with alpha energy but still an agreement of 20% applies to all materials with reliable elemental production yields (a few exceptions are identified). The calculated neutron energy distributions describe the experimental data, with NEDIS retrieving very well the detailed features. USD generally underestimates the measured yields, in particular for compounds with heavy elements and/or at high alpha energies. The energy distributions exhibit sharp peaks that do not match the observations. These findings may be caused by a poor accounting of the alpha particle energy loss by the code. A big variability was found among the calculated neutron production yields for alphas from Sm decay; the lack of yield measurements for low (∼2 MeV) alphas does not allow us to conclude on the codes' accuracy in this energy region. (authors)