Nuclear Science and Engineering / Volume 140 / Number 1 / January 2002 / Pages 86-95
Double-differential cross sections (spectra) for light charged particle (proton, deuteron, triton, and alpha) emission in fast neutron-induced reactions on aluminum are reported for eight incident neutron energies between 25 and 55 MeV, augmenting previous results at 63 MeV. Angular distributions were measured at 15 laboratory angles between 20 and 160 deg. Procedures for data taking and data reduction are presented. Deduced energy-differential and total production cross sections are also reported. Experimental cross sections are compared to existing experimental proton-induced data and to nuclear model calculations that include preequilibrium and compound nucleus decay mechanisms. These calculations formed the basis of a recent set of higher-energy ENDF/B-VI data evaluations (the LA150 Library), and therefore, the present measurements facilitate a testing of the accuracy of these evaluated cross sections. This is important for accelerator-driven-systems design, where radiation transport simulation codes require accurate nuclear data to guide engineering design. Comparisons between the experimental data and the calculated values indicate that while proton, triton, and alpha-particle emission are modeled fairly accurately, deuteron emission is only poorly described, and further improvements to the nuclear reaction models for preequilibrium cluster emission are needed.