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 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 | 0.009 | 0.007 |
| Meta-epidemiology (narrow) | 0.006 | 0.010 |
| Meta-epidemiology (broad) | 0.003 | 0.011 |
| Bibliometrics | 0.003 | 0.006 |
| Science and technology studies | 0.008 | 0.010 |
| Scholarly communication | 0.008 | 0.008 |
| Open science | 0.013 | 0.013 |
| Research integrity | 0.009 | 0.011 |
| Insufficient payload (model declined to judge) | 0.187 | 0.014 |
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".