Decay spectroscopy of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Eu</mml:mi><mml:mprescripts/><mml:none/><mml:mn>160</mml:mn></mml:mmultiscripts></mml:math>: Quasiparticle configurations of excited states and structure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mi>K</mml:mi><mml:mi>π</mml:mi></mml:msup><mml:mo>=</mml:mo><mml:msup><mml:mn>4</mml:mn><mml:mo>+</mml:mo></mml:msup></mml:mrow></mml:math> bandheads in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Gd</mml:mi><mml:mprescripts/><mml:none/><mml:mn>160</mml:mn></mml:mmultiscripts></mml:math>
Bibliographic record
Abstract
Background: Detailed spectroscopy of neutron-rich, heavy, deformed nuclei is of broad interest for nuclear astrophysics and nuclear structure. Nuclei in the $r$-process path and following freeze-out region impact the resulting $r$-process abundance distribution, and the structure of nuclei midshell in both proton and neutron number helps to understand the evolution of subshell gaps and large deformation in these nuclei.Purpose: We aim to improve the understanding of the nuclear structure of $^{160}\mathrm{Gd}$, specifically the ${K}^{\ensuremath{\pi}}={4}^{+}$ bands, as well as study the $\ensuremath{\beta}$ decay of $^{160}\mathrm{Eu}$ into $^{160}\mathrm{Gd}$.Methods: High-statistics decay spectroscopy of $^{160}\mathrm{Gd}$ resulting from the $\ensuremath{\beta}$-decay of $^{160}\mathrm{Eu}$ was collected using the GRIFFIN spectrometer at the TRIUMF-ISAC facility.Results: Two new excited states and ten new transitions were observed in $^{160}\mathrm{Gd}$. The $\ensuremath{\beta}$-decaying half-lives of the low- and high-spin isomers in $^{160}\mathrm{Eu}$ were determined, and the low-spin state's half-life was measured to be ${t}_{1/2}=26.0(8)$ s, $\ensuremath{\approx}16%$ shorter than previous measurements. Lifetimes of the two ${K}^{\ensuremath{\pi}}={4}^{+}$ bandheads in $^{160}\mathrm{Gd}$ were measured for the first time, as well as $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ angular correlations and mixing ratios of intense transitions out of those bandheads.Conclusions: Lifetimes and mixing ratios suggest that the hexadecapole phonon model of the ${K}^{\ensuremath{\pi}}={4}^{+}$ bandheads in $^{160}\mathrm{Gd}$ is preferred over a simple two-state strong mixing scenario, although further theoretical calculations are needed to fully understand these states. Additionally, the 1999.0-keV state in $^{160}\mathrm{Gd}$ heavily populated in $\ensuremath{\beta}$ decay is shown to have positive parity, which raises questions regarding the structure of the high-spin $\ensuremath{\beta}$-decaying state in $^{160}\mathrm{Eu}$.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.083 | 0.028 |
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".