Linear coupling and tune adjustment for the 500 MeV cyclotron
Bibliographic record
Abstract
The horizontal and vertical betatron tunes vary during acceleration in TRIUMF 500 MeV cyclotron, leading the beam to cross the linear coupling resonance ${\ensuremath{\nu}}_{r}\ensuremath{-}{\ensuremath{\nu}}_{z}=1$ multiple times. This results in a measurable transfer of betatron amplitude between the horizontal and the vertical planes. In this paper, we report the observation of an unanticipated crossing of this resonance which cannot be understood from the tune diagram derived from the original magnetic field survey of the cyclotron. We present how we have resolved this conundrum and the technique we have developed to measure the vertical tune, which is particularly challenging in a cyclotron. To correct the deleterious effects of this particular crossing, rather than canceling the resonance driving term, a new strategy was adopted whereby the vertical tune is adjusted locally and pushed away from the resonance line. This is accomplished using the axial field of trim coils, while also maintaining the overall isochronism of the machine.
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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 | 0.001 |
| 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) | 0.002 | 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 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".