Observation of Doppler broadening in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>β</mml:mi></mml:math>-delayed proton-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi></mml:math>decay
Bibliographic record
Abstract
Background: The Doppler broadening of $\ensuremath{\gamma}$-ray peaks due to nuclear recoil from $\ensuremath{\beta}$-delayed nucleon emission can be used to measure the energies of the nucleons. This method has never been tested using $\ensuremath{\beta}$-delayed proton emission or applied to a recoil heavier than $A=10$.Purpose: To test and apply this Doppler broadening method using $\ensuremath{\gamma}$-ray peaks from the $^{26}\mathrm{P}(\ensuremath{\beta}p\ensuremath{\gamma})^{25}\mathrm{Al}$ decay sequence.Methods: A fast beam of $^{26}\mathrm{P}$ was implanted into a planar Ge detector, which was used as a $^{26}\mathrm{P} \ensuremath{\beta}$-decay trigger. The SeGA array of high-purity Ge detectors was used to detect $\ensuremath{\gamma}$ rays from the $^{26}\mathrm{P}(\ensuremath{\beta}p\ensuremath{\gamma})^{25}\mathrm{Al}$ decay sequence.Results: Radiative Doppler broadening in $\ensuremath{\beta}$-delayed proton-$\ensuremath{\gamma}$ decay was observed for the first time. The Doppler broadening analysis method was verified using the 1613-keV $\ensuremath{\gamma}$-ray line for which the proton energies were previously known. The 1776-keV $\ensuremath{\gamma}$ ray de-exciting the 2720 keV $^{25}\mathrm{Al}$ level was observed in $^{26}\mathrm{P}(\ensuremath{\beta}p\ensuremath{\gamma})^{25}\mathrm{Al}$ decay for the first time and used to determine that the center-of-mass energy of the proton emission feeding the 2720-keV level is $5.1\phantom{\rule{0.28em}{0ex}}\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0.28em}{0ex}}1.0$ (stat.) $\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0.28em}{0ex}}0.6$ (syst.) MeV, corresponding to a $^{26}\mathrm{Si}$ excitation energy of $13.3\phantom{\rule{0.28em}{0ex}}\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0.28em}{0ex}}1.0$ (stat.) $\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0.28em}{0ex}}0.6$ (syst.) MeV for the proton-emitting level.Conclusions: The Doppler broadening method has been demonstrated to provide practical measurements of the energies for $\ensuremath{\beta}$-delayed nucleon emissions populating excited states of nuclear recoils at least as heavy as $A=25$.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".