Navigating the pitfalls of relic neutrino detection

TL;DR

This paper discusses the quantum limitations of using beta-decaying isotopes in solid-state detectors for Cosmic Neutrino Background detection, highlighting that the commonly used tritium isotope is unsuitable and proposing alternatives needing further research.

Contribution

It introduces a fundamental quantum usability criterion for beta-decayers in C$ u$B detection and demonstrates that tritium fails this criterion, suggesting the need for alternative isotopes.

Findings

$^3$H fails the usability criterion for C$ u$B detection.

A list of potentially suitable isotopes is provided.

Further research is needed to confirm their effectiveness.

Abstract

Beta-spectrum of radioactive atoms was long ago predicted to bear an imprint of the Cosmic Neutrino Background (C$\nu$B). Over the years, it has been recognised that the best chance of achieving the signal-to-noise ratio required for the observation of this effect lies with solid-state designs. Here we bring to the fore a fundamental quantum limitation on the type of beta-decayer that can be used in such a design. We derive a simple usability criterion and show that $^3\rm H$, which is the most popular choice, fails to meet it. We provide a list of potentially suitable isotopes and discuss why their use in C$\nu$B detection requires further research.