Implantation profiles of muon and secondary positron simulated by Geant4

Abstract

The distribution of muon beams and secondary positrons can be vital reference data for the application of the accelerator muon transmission imaging technique. In this study, the distribution of muon beams and secondary positrons in biological tissue, semiconductors, and metals was simulated using Geant4. The muon beam showed an extremely concentrated decay area, which presented quite high depth resolution (FWHM ranging from 1.68 cm to 11.83 cm) and great penetrability (mean depth ranging from 18.03 cm to 198.97 cm) in media. Based on the simulation data, an empirical equation was designed for the quick calculation of muon beams with different energies in various materials. Additionally, the secondary positrons distribution of a 200 MeV muon beam centered on its decay position and covered an 8.50 cm radius area in Fe. The number of positrons was much higher than that of primary muons, especially in high-density materials. As a consequence of these two aspects, the combined signal processing of muons and secondary positrons provides the potential to improve muon imaging.