Global Antineutrino Modeling for a Web Application

Abstract

Antineutrinos stream freely from rapidly decaying fission products within the cores of nuclear reactors and from long-lived natural radioactivity within the rocky layers of the Earth. These global antineutrinos produce detectable signals in large ultra-clear volumes of water- or hydrocarbon-based target liquids, which are viewed by inward-facing photomultiplier tubes. Detected antineutrinos provide information about their shrouded sources and about the fundamental properties of neutrinos themselves. This paper presents the input data, formulae, and plots resulting from the calculations, which, in addition to the time-dependent reaction rates and energy spectra, model the directions of the antineutrinos from IAEA-registered nuclear power reactors and of the neutrinos from $^8$B decay in the Sun. The model includes estimates of the steady state reaction rates and energy spectra of the antineutrinos from the crust and mantle of the Earth. Results are available for any location near the surface of the Earth and comprise both quasi-elastic scattering on free protons and elastic scattering on atomic electrons. This paper compares model results for two underground locations, the Boulby Mine in the United Kingdom and the Morton Salt Mine in the United States. Operational nuclear power reactors are within about $20$ kilometers of these mines, making them candidate sites for antineutrino detectors capable of identifying, monitoring, and locating remote nuclear activity. The model, which is implemented in a web application at https://geoneutrinos.org/reactors/, provides references for the input data and the formulae, as well as an interactive calculator of the significance of the rate of any of the neutrino sources relative to other sources taken as background.