Sci‐Fri PM: Planning‐09: An EGSnrc investigation of ion chamber response to Co‐60 beams
Bibliographic record
Abstract
The EGSnrc Monte Carlo code was evaluated for its ability to calculate the relative response of a variety of ion chambers to Co-60 beams as a means of justifying the use of this code in future investigations of cavity theory. EGSnrc calculations were compared to measurements with four separate ion chambers, which were each configured with several wall materials (ranging from plastic to lead) and cavity sizes (or cavity air pressures). The experimental results included measurements by Nilsson et al. in 1992, and experiments by Whyte, Attix et al. and Cormack and Johns in the mid-to-late 1950's designed to evaluate Spencer-Attix cavity theory. Experiments by Whyte involved measurements of the response per unit mass as a function of cavity air pressure for a large cylindrical chamber, whereas the other experiments consisted of measurements of the response per unit mass (or ionization current) as a function of the distance between the front and back wall (cavity height) of a plane-parallel chamber. EGSnrc calculations, which could account for the change in response associated with changes in wall material in most cases, were generally within 1-3% of experimental values, even for experimental data that required calculations of unreported wall corrections determined using experimental techniques. The ability of EGSnrc to accurately model these experiments, which showed variations up to 300%, confirms its suitability for detailed Monte Carlo studies of cavity theory.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".