Quasifree (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>p</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math>) scattering of light neutron-rich nuclei near <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mn>14</mml:mn></mml:mrow></mml:math>
Bibliographic record
Abstract
Background: For many years, quasifree scattering reactions in direct kinematics have been extensively used to study the structure of stable nuclei, demonstrating the potential of this approach. The $\mathrm{R}^{3}\mathrm{B}$ collaboration has performed a pilot experiment to study quasifree scattering reactions in inverse kinematics for a stable $^{12}\mathrm{C}$ beam. The results from that experiment constitute the first quasifree scattering results in inverse and complete kinematics. This technique has lately been extended to exotic beams to investigate the evolution of shell structure, which has attracted much interest due to changes in shell structure if the number of protons or neutrons is varied.Purpose: In this work we investigate for the first time the quasifree scattering reactions ($p,pn$) and ($p,2p$) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from $N=14$ to $N=15$.Method: The structure of the projectiles $^{23}\mathrm{O}, ^{22}\mathrm{O}$, and $^{21}\mathrm{N}$ has been studied simultaneously via ($p,pn$) and ($p,2p$) quasifree knockout reactions in complete inverse kinematics, allowing the investigation of proton and neutron structure at the same time. The experimental data were collected at the ${\mathrm{R}}^{3}\mathrm{B}$-LAND setup at GSI at beam energies of around 400 MeV/u. Two key observables have been studied to shed light on the structure of those nuclei: the inclusive cross sections and the corresponding momentum distributions.Conclusions: The knockout reactions ($p,pn$) and ($p,2p$) with radioactive beams in inverse kinematics have provided important and complementary information for the study of shell evolution and structure. For the ($p,pn$) channels, indications of a change in the structure of these nuclei moving from $N=14$ to $N=15$ have been observed, i.e., from the $0{d}_{5/2}$ shell to the $1{s}_{1/2}$. This supports previous observations of a subshell closure at $N=14$ for neutron-rich oxygen isotopes and its weakening for the nitrogen isotopes.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.003 | 0.004 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.056 | 0.019 |
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".