Results of a search for 2\beta-decay of Xe-136 with high pressure copper proportional counters in Baksan Neutrino Observatory INR RAS

TL;DR

This study searches for double beta decay of Xe-136 using high-pressure copper proportional counters at Baksan Neutrino Observatory, measuring half-lives and setting limits on neutrinoless decay modes.

Contribution

It provides experimental measurements of Xe-136 double beta decay half-life and establishes new lower limits on neutrinoless decay half-life using a novel detection method.

Findings

Measured two-neutrino double beta decay half-life as approximately 5.5 x 10^{21} years.

No evidence found for neutrinoless double beta decay.

Set a lower limit of 4.9 x 10^{23} years on neutrinoless decay half-life.

Abstract

Search for \beta \beta -decay of Xe-136 with two high pressure proportional counters is carried out in Baksan Neutrino Observatory. The experiment is based on comparision of spectra measured with natural and enriched xenon. The measured halfe life is equal to T_{1/2}=5.5^{+4.6}_{-1.7} \cdot 10^{21} yr (67% C.L.) for \beta \beta 2\nu -decay mode. No evidence has been found for neutrinoless \beta \beta -decay. The decay half life limit based on data measured during 17280 h is T_{1/2}(\beta\beta 0\nu)\geq 4.9 \cdot 10^{23} yr (90% C.L.).