Searches for Double Beta Decay of ${}^{134}$Xe with EXO-200

Abstract

Searches for double beta decay of ${}^{134}$Xe were performed with EXO-200, a single-phase liquid xenon detector designed to search for neutrinoless double beta decay of ${}^{136}$Xe. Using an exposure of $29.6\text{ kg}\cdot \text{yr}$, the lower limits of ${\text{T}}_{1/2}^{2\hat{I}½{\hat{I}}^2{\hat{I}}^2}>8.7\cdot 10^{20}\text{ yr}$ and ${\text{T}}_{1/2}^{0\hat{I}½{\hat{I}}^2{\hat{I}}^2}>1.1\cdot 10^{23}\text{ yr}$ at 90% confidence level were derived, with corresponding half-life sensitivities of $1.2\cdot 10^{21}\text{ yr}$ and $1.9\cdot 10^{23}\text{ yr}$. These limits exceed those in the literature for ${}^{134}$Xe, improving by factors of nearly $10^5$ and 2 for the two antineutrino and neutrinoless modes, respectively.

8 pages, 4 figures