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Effect of glancing collisions in the cold-atom vacuum standard
Stephen P Eckel1, Daniel S Barker1, James A Fedchak1
1Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Physical Review. A
|March 31, 2025
Summary
Glancing collisions impact ultra-high vacuum (UHV) pressure readings in cold atom vacuum standards (CAVS). Our probabilistic model shows these collisions alter atom loss rates, affecting UHV measurements.
Area of Science:
- Atomic physics
- Vacuum science
- Metrology
Background:
- Cold atom vacuum standards (CAVS) offer precise UHV pressure measurements.
- Traditional pressure standards exist but have limitations.
- Understanding atom loss mechanisms in CAVS is crucial for accuracy.
Purpose of the Study:
- To theoretically investigate the impact of glancing collisions on UHV pressure readings in CAVS.
- To develop a probabilistic model for atom loss due to glancing collisions.
- To update existing comparisons between CAVS and traditional pressure standards.
Main Methods:
- Development of a wholly probabilistic theoretical model.
- Simulation of atom loss in CAVS using ultracold 7Li and 87Rb atoms.
- Updating recent experimental results by incorporating the new theoretical model.
Main Results:
- The number of ultracold atoms remaining in the trap follows a non-exponential decay.
- Glancing collisions shift theoretical loss rate coefficients for 7Li by up to 0.6%.
- Experimentally extracted loss rate coefficients for 87Rb shift by up to 2.2% in the zero trap depth limit.
Conclusions:
- Glancing collisions are a significant factor affecting UHV pressure measurements in CAVS.
- The developed probabilistic model provides a more accurate representation of atom loss.
- Updated comparisons highlight the necessity of accounting for glancing collisions in CAVS metrology.
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