A search for neutrinoless double-β decay (0νββ) in Xe136 is performed with the full EXO-200 dataset using a deep neural network to discriminate between 0νββ and background events. Relative to previous analyses, the signal detection efficiency has been raised from 80.8% to 96.4±3.0%, and the energy resolution of the detector at the Q value of Xe136 0νββ has been improved from σ/E=1.23% to 1.15±0.02% with the upgraded detector. Accounting for the new data, the median 90% confidence level 0νββ half-life sensitivity for this analysis is 5.0×1025 yr with a total Xe136 exposure of 234.1 kg yr. No statistically significant evidence for 0νββ is observed, leading to a lower limit on the 0νββ half-life of 3.5×1025 yr at the 90% confidence level.

Physical Review Letters
Department of Physics

Anton, G. (G.), Badhrees, I. (I.), Barbeau, P.S. (P. S.), Beck, D. (D.), Belov, V. (V.), Bhatta, T. (T.), … Ziegler, T. (T.). (2019). Search for Neutrinoless Double- β Decay with the Complete EXO-200 Dataset. Physical Review Letters, 123(16). doi:10.1103/PhysRevLett.123.161802