Implementation of muon interaction models in PHITS

Abe, Shinichiro   ; Sato, Tatsuhiko   

There are several researches for application of muons, e.g. the visualization of inner-structure of nuclear reactors by using high-energy cosmic-ray muons, nuclear transmutation of long-lived fission products (LLFPs) and nondestructive elemental analysis by using low-energy negative muon. In this study, we construct models for muon interactions (i.e., bremsstrahlung, electron-positron pair production, muon photonuclear interaction, and negative muon capture reaction) and implement them into PHITS in order to make PHITS available for investigations of muon application. The improved PHITS agrees well with experimental data not only for the vertical intensities of cosmic-ray muons in water and standard rock, but also for neutron production by muon photonuclear interaction and negative muon capture reaction. The improved PHITS can also reproduce the cross-section of radionuclide production by muons passing through a concrete wall very well. These results indicate the applicability of the improved PHITS to the shielding design of muon facilities in which estimations of attenuation length and induced radioactivity are important.