Abstract
The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double- decay in . The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in ) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at and a very low background with no observed candidate events in 9.95 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of (90% C.L.). This result constrains the effective Majorana neutrino mass to below 240–520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is .
- Received 8 November 2017
- Revised 9 January 2018
- Corrected 28 March 2018
DOI:https://doi.org/10.1103/PhysRevLett.120.132502
© 2018 American Physical Society
Physics Subject Headings (PhySH)
Corrections
28 March 2018
Correction: The arXiv number in Ref. [40] was corrected.
Viewpoint
The Hunt for No Neutrinos
Published 26 March 2018
Four experiments have demonstrated new levels of sensitivity to neutrinoless double-beta decay, a process whose existence would prove that neutrinos are their own antiparticles.
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