The CFHT MegaCam 40 CCDs camera: cryogenic design and CCD integration
Bibliographic record
Abstract
MegaCam is an imaging camera with a 1 square degree field of view for the new prime focus of the 3.6 meter Canada-France-Hawaii Telescope. In building the MegaCam mosaic we encountered unprecedented challenges from both the large size of each CCD device (2K x 4.5K with 13.5 micron square pixels each) and the large size of the mosaic in which 40 devices have been assembled in a nearly 4-buttable edge manner on a cold plate. The CCD mosaic flatness of ± 16 μm has been optically checked at its nominal functioning temperature. The CCD mosaic is cooled at 153 K with a cryogenic unit; a close cycle pulsed tube with a power of 90 W at 140 K. A cold capacity, allows a slow warm-up during cooling shutdowns and a thermal dispatching leads to a temperature uniformity better than 3 K on the whole mosaic. The camera cryostat is designed in order to have easy access to the CCDs. The vacuum needed to avoid CCD contamination, leaded us to the use of low out-gassing materials in the cryostat. The instrument was delivered to the observatory on June 10, 2002 and first light is scheduled in October 2002.
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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 | 0.001 | 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 | 0.001 | 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".