Search for double beta decay of $^{116}$Cd with enriched $^{116}$CdWO$_4$ crystal scintillators (Aurora experiment)

TL;DR

The Aurora experiment investigates double beta decay of $^{116}$Cd using enriched crystal scintillators, measuring the half-life for two-neutrino decay and setting new limits on neutrinoless decay modes, contributing to neutrino physics research.

Contribution

This study provides the most accurate measurement of $^{116}$Cd's two-neutrino double beta decay half-life and establishes new experimental limits on neutrinoless decay modes.

Findings

Measured $^{116}$Cd two-neutrino decay half-life as (2.62±0.14)×10^{19} yr.

Set lower limit on neutrinoless decay half-life at 1.9×10^{23} yr.

Derived limits on double beta decay to excited states and Majoron emission.

Abstract

The Aurora experiment to investigate double beta decay of $^{116}$Cd with the help of 1.162 kg cadmium tungstate crystal scintillators enriched in $^{116}$Cd to 82\% is in progress at the Gran Sasso Underground Laboratory. The half-life of $^{116}$Cd relatively to the two neutrino double beta decay is measured with the highest up-to-date accuracy $T_{1/2}=(2.62\pm0.14)\times10^{19}$ yr. The sensitivity of the experiment to the neutrinoless double beta decay of $^{116}$Cd to the ground state of $^{116}$Sn is estimated as $T_{1/2} \geq 1.9\times10^{23}$ yr at 90\% CL, which corresponds to the effective Majorana neutrino mass limit $\langle m_{\nu}\rangle \leq (1.2-1.8)$ eV. New limits are obtained for the double beta decay of $^{116}$Cd to the excited levels of $^{116}$Sn, and for the neutrinoless double beta decay with emission of majorons.