Neutron Emission of the Lunar Surface at the Poles

The lunar surface in the vicinity of the poles has special properties compared to the surface at the equator and at moderate latitudes. First, the polar regolith contains quite a large amount of water ice, which significantly affects the neutron radiation generated under the influence of galactic cosmic rays. Second, the temperature of the polar regolith can have extremely low values of about 25 K, as a result of which the thermal component of the neutron flux is partially held in the gravitational field. Based on numerical modeling of neutron radiation from the lunar surface, its main features were shown for the polar regions compared to the equatorial ones: a significant decrease in the ratio of epithermal and thermal neutron fluxes due to an increase in the concentration of hydrogen in the regolith, as well as a significant increase in the density of thermal neutrons near the surface due to gravitational capture.