High-precision half-life determination for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="bold">Na</mml:mi><mml:mprescripts/><mml:none/><mml:mn>21</mml:mn></mml:mmultiscripts></mml:math> using a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>4</mml:mn><mml:mi>π</mml:mi></mml:mrow></mml:math> gas-proportional counter
Bibliographic record
Abstract
A high-precision half-life measurement for the superallowed ${\ensuremath{\beta}}^{+}$ transition between the isospin $T=1/2$ mirror nuclei $^{21}\mathrm{Na}$ and $^{21}\mathrm{Ne}$ has been performed at the TRIUMF-ISAC radioactive ion beam facility yielding ${T}_{1/2}=22.4506(33)$ s, a result that is a factor of 4 more precise than the previous world-average half-life for $^{21}\mathrm{Na}$ and represents the single most precisely determined half-life for a transition between mirror nuclei to date. The contribution to the uncertainty in the $^{21}\mathrm{Na} \mathcal{F}{t}^{\mathrm{mirror}}$ value due to the half-life is now reduced to the level of the nuclear-structure-dependent theoretical corrections, leaving the branching ratio as the dominant experimental uncertainty.
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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 | 0.004 | 0.007 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.039 | 0.022 |
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".