Lunar antineutrinos and heat: fluxes from primordial radioactivity

Abstract: We estimate the fluxes of heat and antineutrinos due to primordial radioactivity within the moon. We use a radial density profile, specifying an inner core and a model-averaged crust. Thickness, density, and elevation of the lunar crust are from remote measurements of the gravitational field. Lateral and vertical variations of thorium, uranium, and potassium abundances in the crust follow from a prediction of the lunar bulk chemical composition. We constrain the total contents of thorium, uranium, and potassium using estimates for the earth's primitive mantle. These contents produce $311\pm37$ GW of radiogenic heating and a surface-averaged heat flux of $8.19\pm0.97$ mW/m$^2$. Our lunar model estimates an antineutrino flux of $(1.83\pm0.32)\times10^6$ cm$^{-2}$s$^{-1}$ and an antineutrino inverse beta decay rate of $5.8\pm1.0$ per $10^{32}$ free proton targets per year, both averaged over the surface.