Nuclear physics for geo-neutrino studies

TL;DR

This paper introduces a direct measurement method for geo-neutrino energy spectra from radioactive decays, providing preliminary results for Bi-214 decay and discussing implications for geo-neutrino detection accuracy.

Contribution

It presents a novel experimental approach for directly measuring geo-neutrino spectra, improving upon theoretical estimates and enabling spectrum distortion tests.

Findings

Feeding probability p_0 = 0.177 ± 0.004 (stat) ^{+0.003}_{-0.001} (sys) for Bi-214

Results are consistent with the Table of Isotopes estimates

Larger data sets could test spectrum distortions from UNSS hypothesis

Abstract

Geo-neutrino studies are based on theoretical estimates of geo-neutrino spectra. We propose a method for a direct measurement of the energy distribution of antineutrinos from decays of long-lived radioactive isotopes. We present preliminary results for the geo-neutrinos from Bi-214 decay, a process which accounts for about one half of the total geo-neutrino signal. The feeding probability of the lowest state of Bi-214 - the most important for geo-neutrino signal - is found to be p_0 = 0.177 \pm 0.004 (stat) ^{+0.003}_{-0.001} (sys), under the hypothesis of Universal Neutrino Spectrum Shape (UNSS). This value is consistent with the (indirect) estimate of the Table of Isotopes (ToI). We show that achievable larger statistics and reduction of systematics should allow to test possible distortions of the neutrino spectrum from that predicted using the UNSS hypothesis. Implications on the geo-neutrino signal are discussed.