Geoneutrinos from the rock overburden at SNO+

TL;DR

This study assesses how the deep underground location of SNO+ affects the detection of Earth's geoneutrinos, showing a ~5% reduction in crustal signal due to the 2 km overburden and modeling the surrounding crust in detail.

Contribution

It provides a refined 3D model of the crust around SNO+ and quantifies the impact of overburden on geoneutrino signal predictions.

Findings

Overburden causes approximately 5% reduction in crustal geoneutrino signal.

Refined 3D crust model improves signal prediction accuracy.

Estimated additional crust contribution from sea level to 300 m.

Abstract

SNOLAB is one of the deepest underground laboratories in the world with an overburden of 2092 m. The SNO+ detector is designed to achieve several fundamental physics goals as a low-background experiment, particularly measuring the Earth's geoneutrino flux. Here we evaluate the effect of the 2 km overburden on the predicted crustal geoneutrino signal at SNO+. A refined 3D model of the 50 x 50 km upper crust surrounding the detector and a full calculation of survival probability are used to model the U and Th geoneutrino signal. Comparing this signal with that obtained by placing SNO+ at sea level, we highlight a $1.4^{+1.8}_{-0.9}$ TNU signal difference, corresponding to the ~5% of the total crustal contribution. Finally, the impact of the additional crust extending from sea level up to ~300 m was estimated.