Single-particle structure of neutron-rich Sr isotopes via <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">H</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mmultiscripts><mml:mi>Sr</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>94</mml:mn><mml:mo>,</mml:mo><mml:mn>95</mml:mn><mml:mo>,</mml:mo><mml:mn>96</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo>,</mml:mo><mml:mo> </mml:mo><mml:mi>p</mml:mi><mml:mo>)</mml:mo></mml:math> reactions
Bibliographic record
Abstract
Background: The region around neutron number $N=60$ in the neutron-rich Sr and Zr nuclei is one of the most dramatic examples of a ground-state shape transition from (near) spherical below $N=60$ to strongly deformed shapes in the heavier isotopes.Purpose: The single-particle structure of $^{95--97}\mathrm{Sr}$ approaching the ground-state shape transition at $^{98}\mathrm{Sr}$ has been investigated via single-neutron transfer reactions using the $(d,p)$ reaction in inverse kinematics. These reactions selectively populate states with a large overlap of the projectile ground state coupled to a neutron in a single-particle orbital.Method: Radioactive $^{94,95,96}\mathrm{Sr}$ nuclei with energies of 5.5 $A\phantom{\rule{0.28em}{0ex}}\mathrm{MeV}$ were used to bombard a ${\mathrm{CD}}_{2}$, where D denotes $^{2}\mathrm{H}$, target. Recoiling light charged particles and $\ensuremath{\gamma}$ rays were detected using a quasi-$4\ensuremath{\pi}$ silicon strip detector array and a 12-element Ge array. The excitation energy of states populated was reconstructed employing the missing mass method combined with $\ensuremath{\gamma}$-ray tagging and differential cross sections for final states were extracted.Results: A reaction model analysis of the angular distributions allowed for firm spin assignments to be made for the low-lying 352, 556, and 681 keV excited states in $^{95}\mathrm{Sr}$ and a constraint has been placed on the spin of the higher-lying 1666 keV state. Angular distributions have been extracted for ten states populated in the $^{2}\mathrm{H}(^{95}\mathrm{Sr},p)^{96}\mathrm{Sr}$ reaction, and constraints have been provided for the spins and parities of several final states. Additionally, the 0, 167, and 522 keV states in $^{97}\mathrm{Sr}$ were populated through the $^{2}\mathrm{H}(^{96}\mathrm{Sr},p)$ reaction. Spectroscopic factors for all three reactions were extracted.Conclusions: Results are compared to shell-model calculations in several model spaces and the structure of low-lying states in $^{94}\mathrm{Sr}$ and $^{95}\mathrm{Sr}$ is well described. The spectroscopic strength of the ${0}^{+}$ and ${2}^{+}$ states in $^{96}\mathrm{Sr}$ is significantly more fragmented than predicted. The spectroscopic factors for the $^{2}\mathrm{H}(^{96}\mathrm{Sr},p)^{97}\mathrm{Sr}$ reaction suggest that the two lowest-lying excited states have significant overlap with the weakly deformed ground state of $^{96}\mathrm{Sr}$, but the ground state of $^{97}\mathrm{Sr}$ has a different structure.
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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 | 0.008 | 0.007 |
| Meta-epidemiology (narrow) | 0.006 | 0.011 |
| Meta-epidemiology (broad) | 0.003 | 0.011 |
| Bibliometrics | 0.003 | 0.007 |
| Science and technology studies | 0.009 | 0.009 |
| Scholarly communication | 0.008 | 0.009 |
| Open science | 0.013 | 0.013 |
| Research integrity | 0.009 | 0.012 |
| Insufficient payload (model declined to judge) | 0.265 | 0.012 |
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".