First Evidence of Solar Neutrino Interactions on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mmultiscripts> <mml:mrow> <mml:mi mathvariant="normal">C</mml:mi> </mml:mrow> <mml:mprescripts/> <mml:none/> <mml:mrow> <mml:mn>13</mml:mn> </mml:mrow> </mml:mmultiscripts> </mml:mrow> </mml:math>
Bibliographic record
Abstract
The SNO+ Collaboration reports the first evidence of ^{8}B solar neutrinos interacting on ^{13}C nuclei. The charged current interaction proceeds through ^{13}C+ν_{e}→^{13}N+e^{-} which is followed, with a 10 minute half life, by ^{13}N→^{13}C+e^{+}+ν_{e}. The detection strategy is based on the delayed coincidence between the electron and the positron. Evidence for the charged current signal is presented with a significance of 4.2σ. Using the natural abundance of ^{13}C present in the scintillator, 5.7 metric tons of ^{13}C over 231 days of data were used in this analysis. The 5.6_{-2.3}^{+3.0} observed events in the data set are consistent with the expectation of 4.7_{-1.3}^{+0.6} events. This result is the second real-time measurement of CC interactions of ^{8}B neutrinos with nuclei and constitutes the lowest energy observation of neutrino interactions on ^{13}C generally. This enables the first direct measurement of the CC ν_{e} reaction to the ground state of ^{13}N, yielding an average cross section of (16.1_{-6.7}^{+8.5}(stat.)_{-2.7}^{+1.6}(syst.))×10^{-43} cm^{2} over the relevant ^{8}B solar neutrino energies.
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.012 | 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".