Search for 2K(2\nu)-capture of Xe-124

TL;DR

This paper reports a search for two-neutrino double K-capture in Xe-124 using a low-background detector, setting a new lower limit on its half-life at 2.0×10^{21} years with 3220 hours of data.

Contribution

It provides the first experimental limit on the half-life of Xe-124 for 2K-capture using a large copper proportional counter.

Findings

Established a new lower limit on Xe-124 2K-capture half-life: ≥ 2.0×10^{21} years.

Used 3220 hours of data with 58.6 g of Xe-124 in a low-background setup.

Demonstrated the feasibility of long-term low-background measurements for rare decay searches.

Abstract

The results of a search for two neutrino mode of double K-capture of Xe-124 using a large copper low-background proportional counter are presented. Data collected during 3220 hours of measurements with 58.6 g of $^{124}$Xe provides us to a new limit on the half-life of Xe-124 regarding 2K-capture at the level: T_{1/2} >= 2.0*10^{21} years at a 90\% confidence level.