Shusuke Hirayama

Validation of nuclear reaction models relevant to cosmic-ray neutron induced single-event effects in microelectronics

The accuracy of nuclear reaction models used in the PHITS (Particle and Heavy Ion Transport code System) code, i.e., the INC model, the QMD model and the event generator mode (e-mode) with the evaluated nuclear data library JENDL-3.3 are validated to apply it to the simulations on single-event effects in advanced microelectronic devices. The model calculations are compared with available experimental data of light-ion production (i.e., proton and alpha particle) from neutron-induced reactions on natSi and 16O, which are the major constituent elements of silicon semiconductor devices over the wide energy range. Comparisons of calculated and measured data for light-ion production indicate that the e-mode calculation with JENDL-3.3 provides better agreement with the experimental data below 20 MeV, and the QMD model reproduces them reasonably well at energies larger than 20 MeV.

Study of pre-equilibrium emission of light complex particles from Fe and Bi induced by intermediate energy neutrons

We have measured double differential cross sections (DDX) for emission of hydrogen- and helium-isotopes in the interaction of 175 MeV quasi-monoenergetic neutrons with Fe and Bi using the Medley setup at the The Svedberg Laboratory (Uppsala, Sweden). We compared experimental DDX with calculations with the TALYS code, which includes exciton model and Kalbach systematics; the code fails to reproduce the emission of complex light ions, generally overestimating it. We propose an correction for the application of the Kalbach phenomenological model in the TALYS code by introducing a new energy dependence for the nucleon transfer mechanism in the pre-equilibrium emission region. Our results suggest also evidence for multiple pre-equilibrium emission of composite particles at 175 MeV.