An improved measurement of the 2\nu \beta \beta\ half-life of Xe-136 with EXO-200

TL;DR

This paper presents a highly precise measurement of the two-neutrino double-beta decay half-life of Xe-136 using the EXO-200 detector, improving accuracy and reducing uncertainties compared to previous measurements.

Contribution

The study provides the most precise measurement of the Xe-136 2 u eta eta" half-life to date, utilizing a large, homogeneous time projection chamber for better systematic control.

Findings

Half-life of Xe-136 2 u eta eta": 2.165 ± 0.016 (stat) ± 0.059 (sys) x 10^21 years

Improved measurement precision over previous results

Detailed analysis methods for double-beta decay searches

Abstract

We report on an improved measurement of the 2\nu \beta \beta\ half-life of Xe-136 performed by EXO-200. The use of a large and homogeneous time projection chamber allows for the precise estimate of the fiducial mass used for the measurement, resulting in a small systematic uncertainty. We also discuss in detail the data analysis methods used for double-beta decay searches with EXO-200, while emphasizing those directly related to the present measurement. The Xe-136 2\nu \beta \beta\ half-life is found to be 2.165 +- 0.016 (stat) +- 0.059 (sys) x 10^21 years. This is the most precisely measured half-life of any 2\nu \beta \beta\ decay to date.