First direct measurement of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>Cu</mml:mi><mml:mprescripts/><mml:none/><mml:mn>59</mml:mn></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>α</mml:mi><mml:mo>)</mml:mo><mml:mmultiscripts><mml:mi>Ni</mml:mi><mml:mprescripts/><mml:none/><mml:mn>56</mml:mn></mml:mmultiscripts></mml:mrow></mml:math>: A step towards constraining the Ni-Cu cycle in the cosmos
Bibliographic record
Abstract
Reactions on proton-rich nuclides drive the nucleosynthesis in core collapse supernovae (CCSNe) and in x-ray bursts (XRBs). CCSNe eject the nucleosynthesis products to the interstellar medium and hence are a potential inventory of $p$ nuclei, whereas in XRBs nucleosynthesis powers the light curves. In both astrophysical sites the Ni-Cu cycle, which features a competition between $^{59}\mathrm{Cu}(p,\ensuremath{\alpha})^{56}\mathrm{Ni}$ and $^{59}\mathrm{Cu}(p,\ensuremath{\gamma})^{60}\mathrm{Zn}$, could potentially halt the production of heavier elements. Here, we report the first direct measurement of $^{59}\mathrm{Cu}(p,\ensuremath{\alpha})^{56}\mathrm{Ni}$ using a reaccelerated $^{59}\mathrm{Cu}$ beam and a cryogenic solid hydrogen target. Our results show that the reaction proceeds predominantly to the ground state of $^{56}\mathrm{Ni}$, and the experimental rate has been found to be lower than Hauser-Feshbach based statistical model predictions. New results hints that the $\ensuremath{\nu}p$ process could operate at higher temperatures than previously inferred and therefore remains a viable site for synthesizing the heavier elements.
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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) | 0.004 | 0.007 |
| Meta-epidemiology (broad) | 0.002 | 0.008 |
| Bibliometrics | 0.002 | 0.005 |
| Science and technology studies | 0.007 | 0.008 |
| Scholarly communication | 0.005 | 0.005 |
| Open science | 0.009 | 0.009 |
| Research integrity | 0.005 | 0.008 |
| Insufficient payload (model declined to judge) | 0.125 | 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; 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".