GEM: a new detector for scanned projection radiography
Bibliographic record
Abstract
While digital radiography using energy-integration detectors is starting to replace screen/film radiography, digital radiography using photon-counting detectors will offer even more benefits. A prototype scanned projection radiography (SPR) system for Xe:CH/sub 4/ imaging has been constructed, which combines a Gas Electron Multiplier (GEM) and a Gas Microstrip Detector (GMD). The energy deposited by each incident photon can be measured when photon counting is done. Both the GEM and the GMD are novel gas-filled counting detectors developed for high-luminosity experiments in particle physics. The GMD is similar to the multiwire proportional chamber except that its anodes and cathodes are strips printed onto a substrate. A prototype photon-counting X-ray imaging system using a Xe:CH/sub 4/ GMD was previously built in our lab, and showed very promising spatial resolution and energy resolution. In order to improve the electrical stability of the GMD imaging system, the GEM is coupled to the GMD as a preamplification element. The GEM, a new concept for electron amplification in gas detectors, is basically a multilayer foil with many high precision holes. Electron amplification happens at the centres of these holes. With the gain contribution from the GEM, the GMD gain and operating voltage can be decreased, thereby improving its reliability. The physical characteristics of the GEM/GMD combination filled with 1 atm Ar:CH/sub 4/ (90:10, by partial pressure) are being tested.
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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
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".