LIQUIDating the Gallium Anomaly

TL;DR

This paper proposes using indium as a target in a new experimental setup to definitively test the gallium anomaly, which suggests potential new physics beyond the Standard Model, by leveraging neutrino capture and coincidence detection.

Contribution

It introduces a novel indium-based detection method with a calibrated cross section and triple coincidence capability to fully explore the gallium anomaly parameter space.

Findings

A 100-ton indium detector with source runs can test the entire gallium anomaly parameter space.

The method can distinguish between sterile neutrino and other BSM scenarios.

Calibration using solar ${}^{7}\text{Be}$ neutrinos enhances measurement accuracy.

Abstract

The gallium anomaly has a global significance of greater than $5\sigma$. Most viable BSM solutions quickly run into strong tensions with reactor and solar neutrino data. We propose to use indium (${}^{115}\text{In}$) as a target as it offers a low threshold and reasonably high cross section. The neutrino-indium charged current cross section can be calibrated using the well-constrained solar ${}^{7}\text{Be}$ neutrino flux that lies very close in energy to the ${}^{51}\text{Cr}$ neutrino lines. The triple coincidence provided by ${}^{115}\text{In}$ neutrino capture can be fully exploited by an opaque scintillation detector that also provides energy and position information. We show that a $100$ ton indium target combined with 2 source runs of a $3.4$ MCi ${}^{51}\text{Cr}$ source can probe the complete parameter space of the gallium anomaly, both in the context of a vanilla sterile neutrino as well as more involved BSM scenarios.