Search for neutrinoless double-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math> decay in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Ge</mml:mi><mml:mprescripts/><mml:none/><mml:mn>76</mml:mn></mml:mmultiscripts></mml:math> with 26 kg yr of exposure from the Majorana Demonstrator
Bibliographic record
Abstract
The Majorana Collaboration is operating an array of high-purity Ge detectors to search for the neutrinoless double-$\ensuremath{\beta}$ decay of $^{76}\mathrm{Ge}$. The Majorana Demonstrator consists of 44.1 kg of Ge detectors (29.7 kg enriched to 88% in $^{76}\mathrm{Ge}$) 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-$\ensuremath{\beta}$ decay in $^{76}\mathrm{Ge}$ with $26.0\ifmmode\pm\else\textpm\fi{}0.5$ kg yr of enriched exposure. With the Demonstrator's energy resolution of 2.53 keV FWHM at ${Q}_{\ensuremath{\beta}\ensuremath{\beta}}$, which is the best among all neutrinoless double-$\ensuremath{\beta}$ 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 $^{76}\mathrm{Ge}$ neutrinoless double-$\ensuremath{\beta}$ decay half-life of $2.7\ifmmode\times\else\texttimes\fi{}{10}^{25}$ yr [90% confidence level (CL)] with a median sensitivity of $4.8\ifmmode\times\else\texttimes\fi{}{10}^{25}$ 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 $11.9\ifmmode\pm\else\textpm\fi{}2.0$ counts/(FWHM t yr).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.018 | 0.006 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".