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 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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.003 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 0.006 |
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".