<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math>-delayed neutron emissions from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>></mml:mo><mml:mn>50</mml:mn></mml:mrow></mml:math> gallium isotopes
Bibliographic record
Abstract
$\ensuremath{\beta}$-delayed $\ensuremath{\gamma}$-neutron spectroscopy has been performed on the decay of $A=84$ to 87 gallium isotopes at the RI-beam Factory at the RIKEN Nishina Center using a high-efficiency array of $^{3}\mathrm{He}$ neutron counters (BRIKEN). $\ensuremath{\beta}\text{\ensuremath{-}}2n\text{\ensuremath{-}}\ensuremath{\gamma}$ events were measured in the decays of all of the four isotopes for the first time, which is direct evidence for populating the excited states of two-neutron daughter nuclei. Detailed decay schemes with the $\ensuremath{\gamma}$ branching ratios were obtained for these isotopes, and the neutron emission probabilities (${P}_{xn}$) were updated from the previous study. Hauser-Feshbach statistical model calculations were performed to understand the experimental branching ratios. We found that the ${P}_{1n}$ and ${P}_{2n}$ values are sensitive to the nuclear level densities of $1n$ daughter nuclei and showed that the statistical model reproduced the ${P}_{2n}/{P}_{1n}$ ratio better when experimental levels plus shell-model level densities fit by the Gilbert-Cameron formula were used as the level-density input. We also showed the neutron and $\ensuremath{\gamma}$ branching ratios are sensitive to the ground-state spin of the parent nucleus. Our statistical model analysis suggested $J\ensuremath{\le}3$ for the unknown ground-state spin of the odd-odd nucleus $^{86}\mathrm{Ga}$, from the ${I}_{\ensuremath{\gamma}}({4}^{+}\ensuremath{\rightarrow}{2}^{+})/{I}_{\ensuremath{\gamma}}({2}^{+}\ensuremath{\rightarrow}{0}^{+})$ ratio of $^{84}\mathrm{Ga}$ and the ${P}_{2n}/{P}_{1n}$ ratio. These results show the necessity of detailed understanding of the decay scheme, including data from neutron spectroscopy, in addition to $\ensuremath{\gamma}$ measurements of the multineutron emitters.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.003 |
| Meta-epidemiology (broad) | 0.001 | 0.004 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.003 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.004 | 0.005 |
| Research integrity | 0.002 | 0.004 |
| Insufficient payload (model declined to judge) | 0.011 | 0.020 |
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; both teacher heads agree on what is shown here.
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".