Design and performance of the double crystal monochromator beamline at the Canadian Light Source
Bibliographic record
Abstract
The medium energy x-ray double crystal monochromator (DCM) is currently being designed at the Canadian Light Source (CLS). Design goals for the DCM are to provide photons between 1750–5500 eV with a resolving power better than 3000 and photon flux better than 5×1010 photons/s/0.1% bandwidth for 500 mA beam current. A set of indium antimonide crystals [InSb(111)] will be used over the energy range of 1750–3700 eV, with resolution ranging from 0.52–1.05 eV. Although InSb allows one to probe the important silicon K edge at ∼1840 eV, it has the disadvantage of poor thermal conductivity. Exposure to high heat loads from the CLS synchrotron on the first crystal (∼56.5 W of power for 2 mrad of horizontal bending magnet radiation, ∼0.54 W/mm2 power density) will cause crystal distortion and thereby intensity/resolution degradation. A second set of silicon crystals [Si(111)] are proposed for the energy range of 3700–5500 eV. Resolution ranges linearly from ∼0.41 to ∼0.70 eV over this energy range. A harmonic filter mirror has been included in the design to reject higher harmonic orders. SHADOW ray-tracing results show that the experimental focus should be 334 μm [horizontal full width at half-maximum (FWHM)]×296 μm (vertical FWHM) when the CLS is operational under 2008 conditions.
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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 | 0.003 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.020 | 0.006 |
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".