Abstract
The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in Ge76. The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in Ge76) 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 Qββ 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 1.9×1025 yr (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 4.0-2.5+3.1 counts/(FWHM t yr).
Original language | English |
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Article number | 132502 |
Journal | Physical Review Letters |
Volume | 120 |
Issue number | 13 |
DOIs | |
State | Published - Mar 26 2018 |
Funding
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Awards No.DE-AC02-05CH11231, No.DE-AC52-06NA25396, No.DE-FG02-97ER41041, No.DE-FG02-97ER41033, No.DE-FG02-97ER41042, No.DE-SC0012612, No.DE-FG02-10ER41715, No.DE-SC0010254, and No.DE-FG02-97ER41020. This material is based upon work supported by the National Science Foundation under Grants No.MRI-0923142, No.PHY-0855314, No.PHY-0919270, No.PHY-1003399, No.PHY-1003940, No.PHY-1102292, No.PHY-1202950, No.PHY-1206314, No.PHY-1619611, and No.PHY-7194299. We acknowledge support from the Russian Foundation for Basic Research, Grant No.15-02-02919. We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD, LBNL/LDRD and PNNL/LDRD Programs. This research used resources of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract No.DE-AC05-00OR22725. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported under Contract No.DE-AC02-05CH11231. We thank our hosts and colleagues at the Sanford Underground Research Facility for their support. The authors appreciate the technical assistance of J. F. Amsbaugh, J. Bell, B. A. Bos, T. H. Burritt, G. Capps, K. Carney, R. Daniels, L. DeBraeckeleer, C. Dunagan, G. C. Harper, C. Havener, G. Holman, R. Hughes, K. Jeskie, K. Lagergren, D. Lee, M. Middlebook, A. Montoya, A. W. Myers, D. Peterson, D. Reid, L. Rodriguez, H. Salazar, A. R. Smith, G. Swift, M. Turqueti, J. Thompson, P. Thompson, C. Tysor, T. D. Van Wechel, and R. Witharm. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Awards No. DE-AC02-05CH11231, No. DE-AC52-06NA25396, No. DE-FG02-97ER41041, No. DE-FG02-97ER41033, No. DE-FG02-97ER41042, No. DE-SC0012612, No. DE-FG02-10ER41715, No. DE-SC0010254, and No. DE-FG02-97ER41020. This material is based upon work supported by the National Science Foundation under Grants No. MRI-0923142, No. PHY-0855314, No. PHY-0919270, No. PHY-1003399, No. PHY-1003940, No. PHY-1102292, No. PHY-1202950, No. PHY-1206314, No. PHY-1619611, and No. PHY-7194299. We acknowledge support from the Russian Foundation for Basic Research, Grant No. 15-02-02919. We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD, LBNL/LDRD and PNNL/LDRD Programs. This research used resources of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract No. DE-AC05-00OR22725. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported under Contract No. DE-AC02-05CH11231. We thank our hosts and colleagues at the Sanford Underground Research Facility for their support.
Funders | Funder number |
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DOE Office of Science | |
LANL/LDRD | |
LBNL/LDRD | |
Office of Nuclear Physics | DE-SC0010254 |
PNNL/LDRD | |
National Science Foundation | PHY-1619611 |
U.S. Department of Energy | |
Directorate for Mathematical and Physical Sciences | 0855314, 0923142, 1102292, 1003940, 0919270, 1003399, 1202950, 1206314 |
Office of Science | DE-AC05-00OR22725, DE-AC02-05CH11231 |
Russian Foundation for Basic Research | 15-02-02919 |
National Science Foundation | PHY-1003399, PHY-1003940, PHY-1206314, PHY-1102292, PHY-0919270, PHY-1202950, MRI-0923142, PHY-0855314, PHY-7194299 |