Fission of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Fr</mml:mi><mml:mprescripts/><mml:none/><mml:mn>215</mml:mn></mml:mmultiscripts></mml:math> studied with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi></mml:math> spectroscopic methods
Bibliographic record
Abstract
Background: Asymmetric fission is known to occur in two regions, the actinides and sublead, and is dependent on the fissioning system excitation energy. Experimental evidence in the sublead region show that this mode is surprisingly persistent with increasing energy and its origin is not fully understood.Purpose: To experimentally study the fusion-fission reaction of $^{215}\mathrm{Fr}$ at moderate excitation energy and determine previously unknown independent fission yields and other properties.Method: The compound nucleus was formed in the reaction $^{18}\mathrm{O}+^{197}\mathrm{Au}$. The prompt $\ensuremath{\gamma}$ rays emitted during the reaction were measured with the high efficiency and high granularity $\ensuremath{\nu}$-ball-2 spectrometer. Independent fission yields of even-even nuclei were determined by detecting triple-gamma cascades in the fission fragments.Results: The observed yields, although dominated by a symmetric peak, show maxima for heavy fragment of $Z\ensuremath{\approx}54--56$, which is consistent with the known results in the actinide region but unexpected for the nuclide of interest, and at the studied excitation energy.Conclusions: The mode of asymmetric fission is present even at relatively high excitation energies in the system studied. This observation matches experimental findings in the sublead region, contrary to the actinides, and so far there is no well-developed explanation of this phenomenon.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 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".