4π NaI(Tl) detector array for in vivo neutron activation analysis
Bibliographic record
Abstract
A 4/spl pi/ /spl gamma/-ray spectrometer has been set up at McMaster Accelerator Laboratory for in vivo neutron activation analysis. To achieve an ideal detection geometry eight long NaI(Tl) detectors with square cross sections were arrayed. A central square hole was left empty for sample access. The pulse processing system comprised a signal sum box, a spectroscopy amplifier and an ADC. Spectrum accumulation in coincidence or anticoincidence mode was also feasible by adding separate shaping and time pick-off electronics to each detector unit. The calibration result showed a fairly high efficiency, a peak efficiency of 0.50 at 1332 keV, due to a sufficient detector thickness of 10.2 cm and a length of 40.6 cm. The spectrometer was used for the aluminum analysis in hand phantoms as the first application. The Al sensitivity and the detection limit achieved for a hand dose of 20 mSv are 1,310 cps/mg, 0.24 mg, respectively. The detection limit has been improved by a factor of 2.5.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.023 | 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".