Accurate determination of an alkali-vapor–inert-gas diffusion coefficient using coherent transient emission from a density grating
Bibliographic record
Abstract
We demonstrate a technique for the accurate measurement of diffusion coefficients for alkali vapor in an inert buffer gas. The measurement was performed by establishing a spatially periodic density grating in isotopically pure $^{87}\mathrm{Rb}$ vapor and observing the decaying coherent emission from the grating due to the diffusive motion of the vapor through ${\mathrm{N}}_{2}$ buffer gas. We obtain a diffusion coefficient of $0.245\ifmmode\pm\else\textpm\fi{}0.002\phantom{\rule{0.16em}{0ex}}{\text{cm}}^{2}/\text{s}$ at $50{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$ and 564 Torr. Scaling to atmospheric pressure, we obtain ${D}_{0}=0.1819\ifmmode\pm\else\textpm\fi{}0.0024\phantom{\rule{0.16em}{0ex}}{\text{cm}}^{2}/\text{s}$. To the best of our knowledge, this represents the most accurate determination of the $\mathrm{Rb}\text{\ensuremath{-}}{\mathrm{N}}_{2}$ diffusion coefficient to date. Our measurements can be extended to different buffer gases and alkali vapors used for magnetometry and can be used to constrain theoretical diffusion models for these systems.
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How this classification was reachedexpand
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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".