Neutron production in the lunar subsurface from alpha particles in galactic cosmic rays
Journal article, 2011

The neutron production from alpha particles in galactic cosmic rays (GCR) in the lunar subsurface has not been estimated with reliable precision despite its importance for lunar nuclear spectroscopy and space dosimetry. Here, we report our estimation of neutron production from GCR nuclei (protons and alpha particles) with the Particle and Heavy Ion Transport code System (PHITS), which includes several heavy ion interaction models. PHITS simulations of the equilibrium neutron density profiles in the lunar subsurface are compared with experimental data obtained in the Apollo 17 Lunar Neutron Probe Experiment. Our calculations successfully reproduced the data within an experimental error of 15%. Our estimation of neutron production from GCR nuclei, estimated by scaling that from protons by a factor of 1.27, is in good agreement within an error of 1% with the calculations using two different alpha particle interaction models in PHITS during a period of average activity of the solar cycle. However, we show that the factor depends on the incident GCR spectrum model used in the simulation. Therefore, we conclude that the use of heavy ion interaction models is important for estimating neutron production in the lunar subsurface.

lunar and planetary spectroscopy

Neutron

PHITS

Moon

alpha particle

SELENE

heavy ion transportation

ray spectrometer

gamma

Author

S. Ota

National Institute of Radiological Sciences

Chalmers, Applied Physics, Nuclear Engineering

Waseda University

Shinji Kobayashi

Japan Aerospace Exploration Agency (JAXA)

Lembit Sihver

Texas A&M University

Chalmers, Applied Physics, Nuclear Engineering

N. Yamashita

Waseda University

N. Hasebe

Waseda University

Earth, Planets and Space

1343-8832 (ISSN) 1880-5981 (eISSN)

Vol. 63 1 25-35

Subject Categories

Subatomic Physics

DOI

10.5047/eps.2010.01.006

More information

Latest update

5/17/2019