Can we use heavy nuclei to detect relic neutrinos?

Abstract

Recent analysis of the viability of solid state-based relic neutrino detectors has revealed the fundamental necessity for the use of heavy, A>100, beta -decayers as neutrino targets. Of all heavy isotopes, and stand out for their sufficiently low decay energies, reasonable half-life times and stable daughter nuclei. However, the crucial bit of information, that is the soft neutrino capture cross-section is missing for both isotopes. The main reason for that is a particular type of beta -decay, which precludes a simple link between the isotope’s half-life time and the neutrino capture rate. In light of the necessity for a reliable estimate of the capture rate – unimpeded by potentially devastating theoretical uncertainties – prior to using the isotope in a full-scale experiment, we propose an experimental method to bypass this difficulty and obtain the capture cross-section of a soft neutrino by a given isotope from the isotope’s beta -spectrum.