Search for $2\nu \beta \beta$ decay of ${}^{136}$Xe to the 0${}_1^{+}$ excited state of ${}^{136}$Ba with EXO-200

Abstract

EXO-200 is a single phase liquid xenon detector designed to search for neutrinoless double-beta decay of ${}^{136}$Xe to the ground state of ${}^{136}$Ba. We report here on a search for the two-neutrino double-beta decay of ${}^{136}$Xe to the first $0^{+}$ excited state, $0_1^{+}$, of ${}^{136}$Ba based on a 100 kg$\cdot$yr exposure of ${}^{136}$Xe. Using a specialized analysis employing a machine learning algorithm, we obtain a 90% CL half-life sensitivity of $1.7\times 10^{24}$ yr. We find no statistically significant evidence for the $2\nu \beta \beta$ decay to the excited state resulting in a lower limit of $T_{1/2}^{2\nu }$ ($0^{+}\to 0_1^{+}$) $>6.9\times 10^{23}$ yr at 90% CL. This observed limit is consistent with the estimated half-life of $2.5\times 10^{25}$ yr.

arXiv comment10 pages, 7 figures, 2 tables

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Cited by in corpus (8)

• Double-Weak Decays of ${}^{124}$Xe and ${}^{136}$Xe in the XENON1T and XENONnT Experiments
• A Rn-220 source for the calibration of low-background experiments
• Cosmogenic activation in double beta decay experiments
• An Optimal Energy Estimator to Reduce Correlated Noise for the EXO-200 Light Readout
• Two-neutrino $\beta \beta$ decay of ${}^{136}$Xe to the first excited $0^{+}$ state in ${}^{136}$Ba
• Search for Two-neutrino Double-Beta Decay of ${}^{136}\mathrm{Xe}$ to the $0_1^{+}$ excited state of ${}^{136}\mathrm{Ba}$ with the Complete EXO-200 Dataset
• Double Beta Decay Experiments at Canfranc Underground Laboratory
• Effective field theories for collective excitations of atomic nuclei