Isotope shifts in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>7</mml:mn><mml:mi>s</mml:mi><mml:mo>→</mml:mo><mml:mn>8</mml:mn><mml:mi>s</mml:mi></mml:mrow></mml:math> transition of francium: Measurements and comparison to <i>ab initio</i> theory
Bibliographic record
Abstract
We observe the electric-dipole forbidden $7s\ensuremath{\rightarrow}8s$ transition in the francium isotopes $^{208\ensuremath{-}211}\mathrm{Fr}$ and $^{213}\mathrm{Fr}$ using a two-photon excitation scheme. We collect the atoms online from an accelerator and confine them in a magneto-optical trap for the measurements. In combination with previous measurements of the $7s\ensuremath{\rightarrow}7{p}_{1/2}$ transition we perform a King plot analysis. We compare the thus-determined ratio of the field shift constants (1.228 $\ifmmode\pm\else\textpm\fi{}$ 0.019) to results obtained from new ab initio calculations (1.234 $\ifmmode\pm\else\textpm\fi{}$ 0.010).
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.011 | 0.002 |
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".