Analysis of spallation product yields for proton-induced reactions

The present research has been made with the aim of applying the proton spallation reaction to the transmutation of transuranic (TRU) nuclides and evaluating what kinds of and amounts of nuclides are produced as spallation products by using a Monte Carlo simulation method. A simulation code NUCLEUS has been developed at JAERI to calculate the nuclear spallation reaction and to compare these results directly with measured nuclear data obtained by thin foil experiments. Mass, isotope and halflife distributions of reaction products are mainly reported for the spallation reactions of some TRU nuclides such as Np and Am with a proton of the energy from 0.5 to 3 GeV. After spallation reactions, a variety of nuclei, especially many neutron-deficient nuclides with mass numbers more than 180, are produced. Discussions are also made on how the mass yield distribution of products varies dependent on the level density parameter a characterizing the particle evaporation in the proton energy of 500 MeV for a 237Np nucleus. (author)