Method to Reduce Noise for Measurement of $^7$Be and $^8$B Solar Neutrinos on Gallium-71

TL;DR

This paper proposes a direct electron and gamma detection method in gallium-based solar neutrino experiments, significantly reducing background noise and focusing on higher energy neutrinos from {}$^8$B and {}$^7$Be fluxes.

Contribution

It introduces a novel detection technique that measures excited nuclear states to lower background noise, enhancing solar neutrino measurement accuracy.

Findings

Potential background reduction by up to 10 orders of magnitude.

Higher energy neutrinos are less suppressed, improving detection of {}$^8$B and {}$^7$Be neutrinos.

Approximate 90% loss of total neutrino signal with the new method.

Abstract

Gallium solar neutrino experiments have historically used radiochemical counting to determine the event rate. A detector which directly measures the ejected electron and de-excitation gamma could reduce background counting rates by way of a double-pulse technique. We find this reduction could be as large as 10 orders of magnitude in a 100 ton detector. In this process, the detector measures the excited nuclear final state of the germanium after an electron neutrino interacts with gallium nucleus through the charged-current interaction. This results in a loss of approximately 90\% of the total neutrino signal, but higher energy processes are less suppressed. The neutrinos resulting from this higher energy selection are predominantly from the {}$^8$B and {}$^7$Be solar neutrino fluxes.