Primary vacuum standard for UHV range — Standing experience and present problems

Peksa, L.; Pražák, Dominik; Gronych, T.; Řepa, P.; Vièar, M.; Tesař, Jiří; Krajíèek, Z.; Stanìk, F.

doi:10.1007/s12647-009-0010-1

Cited by 3 publications

(4 citation statements)

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“…While the chemical composition of the ambient gas has not been measured, other studies show that for ultrahighvacuum setups, in stainlesssteel chambers, molecular hydrogen is by far the most abundant gas appearing due to desorption of atomic hydrogen from the walls [44][45][46]. By using formula (7), we obtain the pressure = × − P 2.8 10 Pa. 9…”

Section: N Tmentioning

confidence: 92%

“…For caesium, C 6 would be twice larger than for lithium regardless of the ambient gas. According to (7), this gives only factor 1.3 increase of the sensitivity. Therefore, sensitivity of lithium vacuometer is not significantly behind other options.…”

Section: Choice Of Trapped Atommentioning

confidence: 99%

“…Metrological pressure standards [7] which are necessary for calibration of the secondary vacuometers produce pres sure down to 10 −10 Pa [8]. The lowest values are achieved in the standards based on continuous expansion of gas flow into known volumes.…”

Section: Introductionmentioning

confidence: 99%

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Primary vacuometer based on an ultracold gas in a shallow optical dipole trap

2016

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A calibrationfree primary vacuometer based on an ultracold atomic gas in a shallow far offresonance optical dipole trap is proposed and demonstrated. The pressure is obtained by measuring the loss of trapped atoms which is caused by collisions with the ambient gas of the vacuum chamber. The loss is related to the ambientgas pressure via a theoretical model based on first principles. The model is applicable owing to elimination of a number of systematic effects which otherwise preclude or complicate construction of a firstprinciple model. These systematics include loss unrelated to collisions with the ambient gas as well as loss dependance on the number and energy of trapped atoms. In the demonstrated vacuometer, the atomnumber decay is exponential with the rate proportional to the pressure, where the proportionality coefficient is expressed via the gas composition and van der Waals coefficients C 6 . Whenever the gas composition is unknown, the systematic error is typically well below that of the hotcathode ionization gauge. The vacuometer is implemented using a gas of ultracold lithium6, which is the optimal working body for such a vacuometer. The lowest measured pressure, × − 2.8 10 9 Pa, is limited by the vacuum in the apparatus, while the dominant error source of 4% is due to uncertainty in the C 6 value and may be improved. Comparison with reading of a hotcathode ionization gauge is also shown. Keywords: pressure measurements, vacuometer, laser cooling and trapping of atoms, atomic and molecular interactions, van der Waals forces

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Section: N Tmentioning

confidence: 92%

Section: Choice Of Trapped Atommentioning

confidence: 99%

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Primary vacuometer based on an ultracold gas in a shallow optical dipole trap

2016

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“…This way to determine the reference is the pressure ratio technique or dynamic reduction, described by Peksa [3]. State of the art continuous expansion apparatuses are usually based on a calculable conductance C which is a fixed orifice with a circular geometry [4,5] whose symmetry axis coincides with that of the vacuum chamber.…”

Section: Introductionmentioning

confidence: 99%