Cosmogenic backgrounds to 0νββ in EXO-200
Bibliographic record
Abstract
As neutrinoless double-beta decay experiments become more sensitive and intrinsic radioactivity in detector materials is reduced, previously minor contributions to the background must be understood and eliminated. With this in mind, cosmogenic backgrounds have been studied with the EXO-200 experiment. Using the EXO-200 TPC, the muon flux (through a flat horizontal surface) underground at the Waste Isolation Pilot Plant (WIPP) has been measured to be $Φ$ = 4.07±0.14 (sys)±0.03 (stat)×10<sup>-7</sup> cm<sup>-2</sup> s<sup>-1</sup>, with a vertical intensity of $I_v$ = 2.97+0.14-0.13 (sys) ± 0.02 (stat) × 10<sup>-7</sup> cm<sup>-2</sup> s<sup>-1</sup> sr<sup>-1</sup>. Simulations of muon-induced backgrounds identified several potential cosmogenic radionuclides, though only <sup>137</sup>Xe is a significant background for the <sup>136</sup>Xe $0νββ$ search with EXO-200. Muon-induced neutron backgrounds were measured using $γ$-rays from neutron capture on the detector materials. This provided a measurement of <sup>137</sup>Xe yield, and a test of the accuracy of the neutron production and transport simulations. The independently measured rates of <sup>136</sup>Xe neutron capture and of <sup>137</sup>Xe decay agree within uncertainties. Geant4 and FLUKA simulations were performed to estimate neutron capture rates, and these estimates agreed to within ~ 40% or better with measurements. The ability to identify <sup>136</sup>Xe($n,γ$) events will allow for rejection of <sup>137</sup>Xe backgrounds in future $0νββ$ analyses.
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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 | 0.000 | 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".