Masses of neutron-rich <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Sc</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>52</mml:mn><mml:mtext>–</mml:mtext><mml:mn>54</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Ti</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>54</mml:mn><mml:mo>,</mml:mo><mml:mn>56</mml:mn></mml:mrow></mml:mmultiscripts></mml:math> nuclides: 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>32</mml:mn></mml:mrow></mml:math> subshell closure in scandium
Bibliographic record
Abstract
Isochronous mass spectrometry has been applied in the storage ring CSRe to measure the masses of the neutron-rich $^{52--54}\mathrm{Sc}$ and $^{54,56}\mathrm{Ti}$ nuclei. The new mass excess values $ME(^{52}\mathrm{Sc})=\ensuremath{-}40525(65)$ keV, $ME(^{53}\mathrm{Sc})=\ensuremath{-}38910(80)$ keV, and $ME(^{54}\mathrm{Sc})=\ensuremath{-}34485(360)$ keV, deviate from the Atomic Mass Evaluation 2012 by $2.3\ensuremath{\sigma}, 2.8\ensuremath{\sigma}$, and $1.7\ensuremath{\sigma}$, respectively. These large deviations significantly change the systematics of the two-neutron separation energies of scandium isotopes. The empirical shell gap extracted from our new experimental results shows a significant subshell closure at $N=32$ in scandium, with a similar magnitude as in calcium. Moreover, we present ab initio calculations using the valence-space in-medium similarity renormalization group based on two- and three-nucleon interactions from chiral effective field theory. The theoretical results confirm the existence of a substantial $N=32$ shell gap in Sc and Ca with a decreasing trend towards lighter isotones, thus providing a consistent picture of the evolution of the $N=32$ magic number from the $pf$ into the $sd$ shell.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.004 | 0.003 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.186 | 0.116 |
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".