Doppler-shift attenuation lifetime measurement of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="bold">Ar</mml:mi><mml:mprescripts/><mml:none/><mml:mn>36</mml:mn></mml:mmultiscripts><mml:mspace width="4.pt"/><mml:msubsup><mml:mn>2</mml:mn><mml:mn>1</mml:mn><mml:mo>+</mml:mo></mml:msubsup></mml:math> level
Bibliographic record
Abstract
At TRIUMF, the TIGRESS Integrated Plunger device and its suite of ancillary detector systems have been implemented for charged-particle tagging and light-ion identification in coincidence with $\ensuremath{\gamma}$-ray spectroscopy for Doppler-shift lifetime studies and low-energy Coulomb excitation measurements. As a test of the device, the lifetime of the first ${2}^{+}$ excited state in $^{36}\mathrm{Ar}$ was measured from the $\ensuremath{\gamma}$-ray line shape of the ${2}_{1}^{+}\ensuremath{\rightarrow}{0}_{\mathrm{g}.\mathrm{s}.}^{+}$ transition using the Doppler-shift attenuation technique following Coulomb excitation. The line-shape signatures, vital for precision lifetime measurements, were significantly improved by enhanced reaction-channel selectivity using a complementary approach of kinematic gating and digital rise-time discrimination of recoiling charged particles in a silicon PIN diode array. The lifetime was determined by comparisons between the data and simulated line shapes generated using our TIGRESS Coulomb excitation code as an input to the Lindhard method, which was then extended and included as a class in geant4. The model-independent lifetime result of $490\ifmmode\pm\else\textpm\fi{}50$ fs corresponds to a reduced quadrupole transition strength of $B(E2;{2}_{1}^{+}\ensuremath{\rightarrow}{0}_{\mathrm{g}.\mathrm{s}.}^{+})=56\ifmmode\pm\else\textpm\fi{}6\phantom{\rule{0.28em}{0ex}}{\mathrm{e}}^{2}{\mathrm{fm}}^{4}$ and agrees well with previous intermediate energy Coulomb excitation measurements, thereby resolving reported discrepancies in the ${2}_{1}^{+}$ level lifetime in this self-conjugate nucleus.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.014 | 0.003 |
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".