Benchmarking Geant4 for Simulating Galactic Cosmic Ray Interactions Within Planetary Bodies

• Published in: Earth and space science (Hoboken, N.J.) Vol. 5; no. 7; pp. 324 - 338
• Main Authors: Mesick, K. E., Feldman, W. C., Coupland, D. D. S., Stonehill, L. C.
• Format: Journal Article
• Language: English
• Published: Hoboken John Wiley & Sons, Inc 01.07.2018; American Geophysical Union (AGU)
• Subjects: Albedo; ASTRONOMY AND ASTROPHYSICS; Cosmic rays; Energy; Gamma rays; Geometry; Laboratories; Meteors & meteorites; Moon; Neutrons; Physics; Planetary Sciences; R&D; Radiation; Research & development; Simulation; Spectrum analysis
• ISSN: 2333-5084; 2333-5084
• DOI: 10.1029/2018EA000400

Galactic cosmic rays undergo complex nuclear interactions with nuclei within planetary bodies that have little to no atmosphere. Radiation transport simulations are a key tool used in understanding the neutron and gamma ray albedo coming from these interactions and tracing these signals back to geochemical composition of the target. We study the validity of the code Geant4 for simulating such interactions by comparing simulation results to data from the Apollo 17 Lunar Neutron Probe Experiment. Different assumptions regarding the physics are explored to demonstrate how these impact the Geant4 simulation results. In general, all of the Geant4 results overpredict the data; however, certain physics lists perform better than others. In addition, we show that results from the radiation transport code MCNP6 are similar to those obtained using Geant4. Key Points Neutron and gamma ray spectroscopy of planetary bodies provides information about hydrogen abundance and geochemical composition Radiation transport simulations of GCR interactions with these bodies are a key tool to predict and interpret data from such measurements In this paper we benchmark Geant4 simulations with the Apollo 17 Lunar Neutron Probe Experiment data