Development of a high magnetic field drift chamber for the chaos spectrometer
Bibliographic record
Abstract
Design considerations for the Canadian High Acceptance Orbit Spectrometer (CHAOS) led to a set of apparently mutually inconsistent requirements for the inner (WC3) drift chamber. This detector chamber has to be cylindrical, of low mass, have excellent spatial resolution (<200 µm) and operate in a variable magnetic field of up to 1.6 T. This thesis describes the investigations which culminated in the testing of a unique new drift chamber which satisfies all the requirements for the CHAOS WC3. An overview is given of present drift chamber technology and its application in high magnetic fields. Methods to obtain the space-time relationship are reviewed. In particular, the integral, displacement and trackfitting methods have been applied to prototype chambers. A trackfitting algorithm developed to calibrate a set of wire chambers and correct systematic wire position offsets is presented. Three types of prototype chambers were designed and constructed. Tests were carried out in beams at TRIUMF to measure the spatial resolution of these chambers in a 1 T magnetic field. The results indicate that a resolution of as σx ≈ µm can be achieved. A simplified model of electron transport through gasses is used to explain electron drift properties in high magnetic field chambers. A method to resolve the usual left-right ambiguity, proposed within the framework of this model, involves the comparison of the charge induced on diagonally opposed cathode strips mounted parallel to the potential wires. After extensive simulations using the Garfield drift chamber program, a final, unique prototype was designed on which the WC3 chamber to be built for CHAOS is now based. A final beam test in a 1.6 T magnetic field showed that the left-right problem is resolved for track angles between -45° and +45°.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 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".