Measurement of the ${}^{136}$Xe two-neutrino double beta decay half-life via direct background subtraction in NEXT

TL;DR

This paper reports a novel measurement of the ${}^{136}$Xe two-neutrino double beta decay half-life using direct background subtraction with a small detector, demonstrating a new background-model-independent approach for neutrinoless double beta decay searches.

Contribution

Introduces a new background subtraction technique applied to double beta decay measurement with a small detector, enabling background-model-independent searches.

Findings

Measured half-life: $2.34^{+0.80}_{-0.46} imes 10^{21}$ years.

Demonstrated feasibility of background-model-independent neutrinoless double beta decay searches.

Used topology of double-electron tracks for analysis.

Abstract

We report a measurement of the half-life of the ${}^{136}$Xe two-neutrino double beta decay performed with a novel direct background subtraction technique. The analysis relies on the data collected with the NEXT-White detector operated with ${}^{136}$Xe-enriched and ${}^{136}$Xe-depleted xenon, as well as on the topology of double-electron tracks. With a fiducial mass of only 3.5 kg of Xe, a half-life of $2.34^{+0.80}_{-0.46}\textrm{(stat)}^{+0.30}_{-0.17}\textrm{(sys)}\times10^{21}~\textrm{yr}$ is derived from the background-subtracted energy spectrum. The presented technique demonstrates the feasibility of unique background-model-independent neutrinoless double beta decay searches.