Abstract
The background index (BI) is an important quantity to project and calculate the half-life sensitivity of neutrinoless double-β decay (0νββ) experiments. An analysis framework is presented to calculate the BI using the specific activities, masses, and simulated efficiencies of an experiments components as distributions. This Bayesian framework includes a unified approach to combine specific activities from assay. Monte Carlo uncertainty propagation is used to build a BI distribution from the specific activity, mass, and efficiency distributions. This method is applied to the Majorana Demonstrator, which deployed arrays of high-purity Ge detectors enriched in Ge76 to search for 0νββ. The original assay-based projection is requantified in the new framework, using the as-built geometry of the Demonstrator and additional assay information. While 47% higher than the original projection, the resulting BI of [8.95±0.36]×10-4cts/(keVkgyr) from the Th232 and U238 decay chains does not account for the higher-Than-expected BI observed by the Demonstrator. This method enables us to demonstrate the statistical incompatibility between the Demonstrator's observed background and the assay results.
| Original language | English |
|---|---|
| Article number | 055804 |
| Journal | Physical Review C |
| Volume | 110 |
| Issue number | 5 |
| DOIs | |
| State | Published - Nov 2024 |
Funding
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contracts/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-SC0017594, No. DE-SC0018060, No. DE-SC0022339, and No. LANLEM77/LANLEM78. 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, No. PHY-1812356, No. PHY-2111140, and No. PHY-2209530. 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, the Oak Ridge National Laboratory LDRD Program, and the Pacific Northwest National Laboratory LDRD Program for this work. We gratefully acknowledge the support of the South Dakota Board of Regents Competitive Research Grant. 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. We acknowledge support from the 2020/2021 L'Or\u00E9al-UNESCO for Women in Science Programme. 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 |
|---|---|
| Oak Ridge National Laboratory LDRD Program | |
| Pacific Northwest National Laboratory | |
| Canada Foundation for Innovation John R. Evans Leaders Fund | |
| Oak Ridge National Laboratory | |
| National Energy Research Scientific Computing Center | |
| Los Alamos National Laboratory | |
| U.S. Department of Energy | |
| South Dakota Board of Regents | |
| Laboratory Directed Research and Development | |
| Office of Science | |
| National Science Foundation | PHY-1003399, PHY-1812409, PHY-1614611, PHY-1206314, PHY-1102292, PHY-2209530, PHY-1812356, MRI-0923142, PHY-2111140 |
| National Science Foundation | |
| Natural Sciences and Engineering Research Council of Canada | SAPIN-2017-00023 |
| Natural Sciences and Engineering Research Council of Canada | |
| Nuclear Physics | DE-AC05-00OR22725, DE-AC05-76RL0130, DE-AC02-05CH11231, DE-SC0012612, DE-FG02-97ER41020, DE-SC0017594, DE-FG02-97ER41033, LANLEM77/LANLEM78, DE-SC0022339, DE-SC0018060, DE-FG02-97ER41041, DE-SC0014445 |
| Nuclear Physics |