Eckel, S.
, Barker, D.
, Fedchak, J.
, Klos, J.
, Scherschligt, J.
and Tiesinga, E.
(2025),
Effect of ``glancing'' collisions in the cold atom vacuum standard, Physical Review A, [online], https://doi.org/10.1103/PhysRevA.111.023317, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956671
(Accessed March 3, 2025)
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Effect of ''glancing'' collisions in the cold atom vacuum standard
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Abstract
We theoretically investigate the effect of "glancing" collisions on the ultra-high-vacuum pressure readings of the cold-atom vacuum standard (CAVS), based on either ultracold $^7$Li or $^87}$Rb atoms. Here, glancing collisions are those collisions between ultracold atoms and room-temperature background atoms or molecules in the vacuum that do not impart enough kinetic energy to eject an ultracold atom from its trap. Our model is wholly probabilistic and shows that the number of the ultracold atoms remaining in the trap as a function of time is nonexponential. We update the recent results of a comparison between a traditional pressure standard—a combined flow meter and dynamic expansion system—and the CAVS [D. S. Barker et al., AVS Quantum Sci. 5, 035001 (2023)] to reflect the results of our model. We find that the effect of glancing collisions shifts the theoretical predictions of the total loss rate coefficients for $^7$Li colliding with noble gases or N$_2$ by up to 0.6 %. Likewise, we find that in the limit of zero trap depth, the experimentally extracted loss rate coefficients for $^87}$Rb colliding with noble gases or N$_2$ shift by as much as 2.2 %Citation
Physical Review A
Volume
111
Pub Type
Journals
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Keywords
cold atoms, vacuum metrology, pressure measurement, primary gauge, standard
Citation
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Created February 12, 2025, Updated February 21, 2025