Abstract
The majorana demonstrator is a neutrinoless double-β decay search consisting of a low-background modular array of high-purity germanium detectors, ∼2/3 of which are enriched to 88% in Ge76. The experiment is also searching for double-beta decay of Ge76 to excited states (e.s.) in Se76. Ge76 can decay into three daughter states of Se76, with clear event signatures consisting of a ββ-decay followed by the prompt emission of one or two γ rays. This results with high probability in multi-detector coincidences. The granularity of the demonstrator detector array enables powerful discrimination of this event signature from backgrounds. Using 41.9 kg yr of isotopic exposure, the demonstrator has set world leading limits for each e.s. decay of Ge76, with 90% CL lower half-life limits in the range of (0.75-4.0)×1024 yr. In particular, for the 2ν transition to the first 0+ e.s. of Se76, a lower half-life limit of 7.5×1023 yr at 90% CL was achieved.
| Original language | English |
|---|---|
| Article number | 015501 |
| Journal | Physical Review C |
| Volume | 103 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 6 2021 |
Funding
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract/Awards No. DE-AC02-05CH11231, No. DE-AC05-00OR22725, No. DE-AC05-76RL0130, No. DE-FG02-97ER41020, No. DE-FG02-97ER41033, No. DE-FG02-97ER41041, No. DE-SC0012612, No. DE-SC0014445, No. DE-SC0018060, and No. LANLEM77. We acknowledge support from the Particle Astrophysics Program and Nuclear Physics Program of the National Science Foundation through Grants No. MRI-0923142, No. PHY-1003399, No. PHY-1102292, No. PHY-1206314, No. PHY-1614611, No. PHY-1812409, and No. PHY-1812356. We gratefully acknowledge the support of the Laboratory Directed Research & Development (LDRD) program at Lawrence Berkeley National Laboratory for this work. We gratefully acknowledge the support of the U.S. Department of Energy through the Los Alamos National Laboratory LDRD Program and through the Pacific Northwest National Laboratory LDRD Program for this work. We acknowledge support from the Russian Foundation for Basic Research, Grant No. 15-02-02919. We acknowledge the support of the Natural Sciences and Engineering Research Council of Canada, funding reference no. SAPIN-2017-00023, and from the Canada Foundation for Innovation John R. Evans Leaders Fund. This research used resources provided by the Oak Ridge Leadership Computing Facility at Oak Ridge National Laboratory and by the National Energy Research Scientific Computing Center, a U.S. Department of Energy Office of Science User Facility. We thank our hosts and colleagues at the Sanford Underground Research Facility for their support.
| Funders | Funder number |
|---|---|
| Canada Foundation for Innovation John R. Evans Leaders Fund | |
| Office of Nuclear Physics | |
| U.S. Department of Energy Office of Science | |
| National Science Foundation | PHY-1812409, 0923142, 1102292, PHY-1206314, PHY-1614611, 1812356, 1003399, PHY-1812356, MRI-0923142, 1206314, PHY-1003399, PHY-1102292, 1812409 |
| U.S. Department of Energy | |
| Office of Science | |
| Nuclear Physics | DE-AC05-00OR22725, DE-AC05-76RL0130, DE-AC02-05CH11231, DE-SC0012612, DE-FG02-97ER41020, DE-FG02-97ER41033, DE-FG02-97ER41041, DE-SC0018060, DE-SC0014445, LANLEM77 |
| Oak Ridge National Laboratory | |
| Laboratory Directed Research and Development | |
| Los Alamos National Laboratory | |
| National Energy Research Scientific Computing Center | |
| Natural Sciences and Engineering Research Council of Canada | SAPIN-2017-00023 |
| Russian Foundation for Basic Research | 15-02-02919 |