Search for neutrinoless double-β decay in ^{76}Ge with 26 kg yr of exposure from the Majorana Demonstrator
Author(s)
Alvis, S. I.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Barton, C. J.; Basu, V.; Bertrand, F. E.; Bos, B.; Busch, M.; Buuck, M.; Caldwell, T. S.; Chan, Y-D.; Christofferson, C. D.; Chu, P.-H.; Clark, M.; Cuesta, C.; Detwiler, J. A.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Gilliss, T.; Giovanetti, G. K.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Haufe, C. R.; Hegedus, R. J.; Hehn, L.; Henning, R.; Hervas Aguilar, D.; Hoppe, E. W.; Howe, M. A.; Kidd, M. F.; Konovalov, S. I.; Kouzes, R. T.; Lopez, A. M.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Myslik, J.; Othman, G.; Pettus, W.; Piliounis, A.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Reine, A. L.; Rielage, K.; Ruof, N. W.; Shanks, B.; Shirchenko, M.; Tedeschi, D.; Varner, R. L.; Vasilyev, S.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C.-H.; Yumatov, V.; Zhitnikov, I.; Zhu, B. X.; ... Show more Show less
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The Majorana Collaboration is operating an array of high-purity Ge detectors to search for the neutrinoless double-β decay of ^{76}Ge. The Majorana Demonstrator consists of 44.1 kg of Ge detectors (29.7 kg enriched to 88% in ^{76}Ge) split between two modules constructed from ultraclean materials. Both modules are contained in a low-background shield at the Sanford Underground Research Facility in Lead, South Dakota. We present updated results on the search for neutrinoless double-β decay in ^{76}Ge with 26.0±0.5 kg yr of enriched exposure. With the Demonstrator's energy resolution of 2.53 keV FWHM at Q_{ββ}, which is the best among all neutrinoless double-β decay experiments, we observe one event in the region of interest with 0.65 events expected from the estimated background, resulting in a lower limit on the ^{76}Ge neutrinoless double-β decay half-life of 2.7×10^{25} yr [90% confidence level (CL)] with a median sensitivity of 4.8×10^{25} yr (90% CL). Depending on the matrix elements used, a 90% CL upper limit on the effective Majorana neutrino mass in the range of 200–433 meV is obtained. The measured background in the configurations with full shielding and optimized grounding is 11.9±2.0 counts/(FWHM t yr).
Date issued
2019-08-23Department
Massachusetts Institute of Technology. Department of PhysicsPublisher
American Physical Society
Citation
Phys. Rev. C 100, 025501 (2019)
Version: Final published version