Measurement of the Antineutrino Spectrum from <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">U</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>235</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> Fission at HFIR with PROSPECT
Bibliographic record
Abstract
This Letter reports the first measurement of the $^{235}\mathrm{U}$ ${\overline{\ensuremath{\nu}}}_{e}$ energy spectrum by PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, operating 7.9 m from the $85\text{ }\text{ }{\mathrm{MW}}_{\mathrm{th}}$ highly enriched uranium (HEU) High Flux Isotope Reactor. With a surface-based, segmented detector, PROSPECT has observed $31678\ifmmode\pm\else\textpm\fi{}304(\mathrm{stat})$ ${\overline{\ensuremath{\nu}}}_{e}$-induced inverse beta decays, the largest sample from HEU fission to date, 99% of which are attributed to $^{235}\mathrm{U}$. Despite broad agreement, comparison of the Huber $^{235}\mathrm{U}$ model to the measured spectrum produces a ${\ensuremath{\chi}}^{2}/\mathrm{ndf}=51.4/31$, driven primarily by deviations in two localized energy regions. The measured $^{235}\mathrm{U}$ spectrum shape is consistent with a deviation relative to prediction equal in size to that observed at low-enriched uranium power reactors in the ${\overline{\ensuremath{\nu}}}_{e}$ energy region of 5--7 MeV.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.003 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.004 | 0.004 |
| Research integrity | 0.001 | 0.003 |
| Insufficient payload (model declined to judge) | 0.263 | 0.004 |
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".