Structure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">Be</mml:mi><mml:mprescripts/><mml:none/><mml:mn>13</mml:mn></mml:mmultiscripts></mml:math> studied in proton knockout from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">B</mml:mi><mml:mprescripts/><mml:none/><mml:mn>14</mml:mn></mml:mmultiscripts></mml:math>
Bibliographic record
Abstract
The neutron-unbound isotope $^{13}\mathrm{Be}$ has been studied in several experiments using different reactions, different projectile energies, and different experimental setups. There is, however, no real consensus in the interpretation of the data, in particular concerning the structure of the low-lying excited states. Gathering new experimental information, which may reveal the $^{13}\mathrm{Be}$ structure, is a challenge, particularly in light of its bridging role between $^{12}\mathrm{Be}$, where the $N=8$ neutron shell breaks down, and the Borromean halo nucleus $^{14}\mathrm{Be}$. The purpose of the present study is to investigate the role of bound excited states in the reaction product $^{12}\mathrm{Be}$ after proton knockout from $^{14}\mathrm{B}$, by measuring coincidences between $^{12}\mathrm{Be}$, neutrons, and $\ensuremath{\gamma}$ rays originating from de-excitation of states fed by neutron decay of $^{13}\mathrm{Be}$. The $^{13}\mathrm{Be}$ isotopes were produced in proton knockout from a 400 MeV/nucleon $^{14}\mathrm{B}$ beam impinging on a ${\mathrm{CH}}_{2}$ target. The $^{12}\mathrm{Be}\text{\ensuremath{-}}n$ relative-energy spectrum $d\ensuremath{\sigma}/d{E}_{fn}$ was obtained from coincidences between $^{12}\mathrm{Be}$(g.s.) and a neutron, and also as threefold coincidences by adding $\ensuremath{\gamma}$ rays, from the de-excitation of excited states in $^{12}\mathrm{Be}$. Neutron decay from the first $5/{2}^{+}$ state in $^{13}\mathrm{Be}$ to the ${2}^{+}$ state in $^{12}\mathrm{Be}$ at 2.11 MeV is confirmed. An energy independence of the proton-knockout mechanism is found from a comparison with data taken with a 35 MeV/nucleon $^{14}\mathrm{B}$ beam. A low-lying $p$-wave resonance in $^{13}\mathrm{Be}(1/{2}^{\ensuremath{-}})$ is confirmed by comparing proton- and neutron-knockout data from $^{14}\mathrm{B}$ and $^{14}\mathrm{Be}$.
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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 | 0.008 |
| Meta-epidemiology (narrow) | 0.004 | 0.003 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.003 | 0.005 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.006 | 0.005 |
| Open science | 0.005 | 0.003 |
| Research integrity | 0.004 | 0.005 |
| Insufficient payload (model declined to judge) | 0.621 | 0.629 |
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".