Effects of charge carrier trapping on polycrystalline PbO x-ray imaging detectors
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Bibliographic record
Abstract
The effects of charge carrier trapping on the x-ray sensitivity, resolution, and detective quantum efficiency (DQE) in polycrystalline lead oxide (PbO) x-ray imaging detectors are theoretically analyzed. The theoretical models for calculating carrier trapping-limited x-ray sensitivity and modulation transfer function (MTF), and DQE incorporating polyenergetic x-ray spectrum are described. A cascaded linear system model is developed for calculating the spatial frequency f dependent DQE of PbO detectors by incorporating the effects of bulk charge carrier trapping on the MTF and the x-ray interaction depth dependent charge collection efficiency and noise. The theoretical calculations are compared with the published experimental data and show a very good agreement. From the fittings of the sensitivity and MTF curves, the electron and hole ranges in polycrystalline PbO are found to be 3.5×10−7 and ∼10−8 cm2/V, respectively. The f dependent noise power spectrum NPS(f) and DQE(f) performances are analyzed as a function of applied electric field and carrier lifetimes. The calculation shows that the carrier trapping is responsible for a 21% reduction in the MTF at the applied field of 1.0 V/μm at the Nyquist frequency (fN) and the aliased NPS at fN is reduced to 63% of that at zero spatial frequency. The sensitivity, MTF, NPS(f), and DQE(f) strongly depend on the applied electric field and carrier ranges. It is found that the DQE(f) for fluoroscopic applications can be improved dramatically by simply enhancing the carrier lifetimes through improving material properties of the PbO sample.
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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 | 0.000 | 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 | 0.000 | 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 it