High-precision Penning trap mass measurements of neutron-rich chlorine isotopes at the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>N</mml:mi> <mml:mo>=</mml:mo> <mml:mn>28</mml:mn> </mml:mrow> </mml:math> shell closure
Bibliographic record
Abstract
Although it is known that the $N=28$ spherical shell closure erodes, the strength of the closure with decreasing proton number $Z<20$ is an open question in nuclear structure. In this region of interest, high-precision mass measurements of neutron-rich $^{43\ensuremath{-}45}\mathrm{Cl}$ isotopes were performed at the Low Energy Beam and Ion Trap when coupled to the National Superconducting Cyclotron Lab. The resulting mass excesses (MEs) are $\mathrm{ME}(^{43}\mathrm{Cl})=\ensuremath{-}24\phantom{\rule{0.16em}{0ex}}114.4(1.7)\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\mathrm{keV}, \mathrm{ME}(^{44}\mathrm{Cl})$ = \ensuremath{-}20 450.8(10.6) keV, and $\mathrm{ME}(^{45}\mathrm{Cl})=\ensuremath{-}18\phantom{\rule{0.16em}{0ex}}240.1(3.7)\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\mathrm{keV}$, and the uncertainty of these masses is improved by up to a factor of $\ensuremath{\sim}40$ compared to the previous values reported in the 2020 Atomic Mass Evaluation. Comparison to ab initio calculations using the Valence-Space In-Medium Similarity Renormalization Group shows good agreement up to and including the closure.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".