Shell-model studies of the astrophysical <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>r</mml:mi><mml:mi>p</mml:mi></mml:mrow></mml:math>-process reactions <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi mathvariant="normal">S</mml:mi><mml:mprescripts/><mml:none/><mml:mn>34</mml:mn></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mo>)</mml:mo><mml:mmultiscripts><mml:mi>Cl</mml:mi><mml:mprescripts/><mml:none/><mml:mn>35</mml:mn></mml:mmultiscripts></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>Cl</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>34</mml:mn><mml:mi>g</mml:mi><mml:mo>,</mml:mo><mml:mi>m</mml:mi></mml:mrow></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mo>)</mml:mo><mml:mmultiscripts><mml:mi>Ar</mml:mi><mml:mprescripts/><mml:none/><mml:mn>35</mml:mn></mml:mmultiscripts></mml:mrow></mml:math>
Bibliographic record
Abstract
Background: Dust grains condensed in the outflows of presolar classical novae should have been present in the protosolar nebula. Candidates for such presolar nova grains have been found in primitive meteorites and can in principle be identified by their isotopic ratios, but the ratios predicted by state-of-the-art one-dimensional hydrodynamic models are uncertain due to nuclear-physics uncertainties.Purpose: To theoretically calculate the thermonuclear rates and uncertainties of the $^{34}\mathrm{S}(p,\ensuremath{\gamma})^{35}\mathrm{Cl}$ and $^{34g,m}\mathrm{Cl}(p,\ensuremath{\gamma})^{35}\mathrm{Ar}$ reactions and investigate their impacts on the predicted $^{34}\mathrm{S}/^{32}\mathrm{S}$ isotopic ratio for presolar nova grains.Method: A shell-model approach in a ($0+1$) $\ensuremath{\hbar}\ensuremath{\omega}$ model space was used to calculate the properties of resonances in the $^{34}\mathrm{S}(p,\ensuremath{\gamma})^{35}\mathrm{Cl}$ and $^{34g,m}\mathrm{Cl}(p,\ensuremath{\gamma})^{35}\mathrm{Ar}$ reactions and their thermonuclear rates. Uncertainties were estimated using a Monte Carlo method. The implications of these rates and their uncertainties on sulfur isotopic nova yields were investigated using a postprocessing nucleosynthesis code. The rates for transitions from the ground state of $^{34}\mathrm{Cl}$ as well as from the isomeric first excited state of $^{34}\mathrm{Cl}$ were explicitly calculated.Results: At energies in the resonance region near the proton-emission threshold, many negative-parity states appear. Energies, spectroscopic factors, and proton-decay widths are reported. The resulting thermonuclear rates are compared with previous determinations.Conclusions: The shell-model calculations alone are sufficient to constrain the variation of the $^{34}\mathrm{S}/^{32}\mathrm{S}$ ratios to within about 30%. Uncertainties associated with other reactions must also be considered, but in general we find that the $^{34}\mathrm{S}/^{32}\mathrm{S}$ ratios are not a robust diagnostic to clearly identify presolar grains made from nova ejecta.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.037 | 0.005 |
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".