A Measurement of the Proton's Weak Charge Using an Integration Cerenkov Detector System
Bibliographic record
Abstract
The Q-weak experiment at Thomas Jefferson National Accelerator Facility (USA) will make a precision determination of the proton weak charge with approximately 4% combined statistical and systematic uncertainties via a measurement of the parity violating asymmetry in elastic electron-proton scattering at very low momentum transfer and forward angle. This will allow an extraction of the weak mixing angle at Q^2=0.026 (GeV/c)^2 to approximately 0.3%. The weak mixing angle is a fundamental parameter in the Standard Model of electroweak interactions. At the proposed accuracy, a measured deviation of this parameter from the predicted value would indicate new physics beyond what is currently described in the Standard Model. Without deviation from the predicted value, this measurement would place stringent limits on possible extensions to the Standard Model and constitute the most precise measurement of the proton's weak charge to date. The key experimental apparatus include a liquid hydrogen target, a toroidal magnetic spectrometer and a set of eight Cerenkov detectors. The Cerenkov detectors form the main detector system for the Q-weak experiment and are used to measure the parity violating asymmetry during the primary Q-weak production runs. The Cerenkov detectors form the main subject of this thesis. Following a brief introduction to the experiment, the design, development, construction, installation, and testing of this detector system will be discussed in detail. This is followed by a detailed discussion of detector diagnostic data analysis and the corresponding detector performance. The experiment has been successfully constructed and commissioned, and is currently taking data. The thesis will conclude with a discussion of the preliminary analysis of a small portion of the liquid hydrogen data.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".