Simulation Study of Halo Collimation in the TRIUMF Ariel Proton Beam Line
Bibliographic record
Abstract
The TRIUMF 500 MeV H⁻ cyclotron uses stripping foil extraction to drive several proton beam lines serving different experimental programs. As part of TRIUMF's Ariel facility now under construction, a new proton beam line 4-North will be installed to transport up to 100 microamps of 480 MeV protons to an ISOL target station for rare isotope beam production. This beam line has been designed for low-loss (< 1nA/m) operation and provides space for a collimator to remove the beam halo produced by large-angle scattering in the cyclotron extraction foil. We have studied proton loss patterns and collimation efficiency using simulation codes: the older REVMOC program and a fully 3D simulation based on Geant4, with all particle interactions in matter included. Scattering in the foil is treated by a separate iterated single-scatter model. Using these tools we arrive at a prototype design for an effective collimator.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".