Ground-state electromagnetic moments of calcium isotopes
Bibliographic record
Abstract
Background: The neutron-rich calcium isotopes have gained particular interest as evidence of closed-shell structures has recently been found in two exotic nuclei, at $N=32$ and $N=34$. Additionally, the study of such neutron-rich systems has revealed new aspects of nuclear forces, in particular regarding the role of three-nucleon forces.Purpose: We study the electromagnetic properties of Ca isotopes around the neutron number $N=32$.Methods: High-resolution bunched-beam collinear laser spectroscopy was used to measure the optical hyperfine spectra of the $^{43\ensuremath{-}51}\mathrm{Ca}$ isotopes.Results: The ground-state magnetic moments of $^{49,51}\mathrm{Ca}$ and quadrupole moments of $^{47,49,51}\mathrm{Ca}$ were measured for the first time, and the $^{51}\mathrm{Ca}$ ground-state spin $I=3$/2 was determined in a model-independent way. Our experimental results are compared with state-of-the-art shell-model calculations using both phenomenological interactions and microscopic interactions derived from chiral effective field theory.Conclusions: The results for the ground-state moments of neutron-rich isotopes are in excellent agreement with predictions of interactions derived from chiral effective field theory including three-nucleon forces. Lighter isotopes illustrate the presence of particle-hole excitations of the $^{40}\mathrm{Ca}$ core in their ground state. Our results provide a critical test of modern nuclear theories, and give direct answer to the evolution of ground-state electromagnetic properties in the Ca isotopic chain across three doubly closed-shell configurations at $N=20$, 28, 32 of this unique system.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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".