Dielectric-constant gas thermometry

Gaiser, Christof; Zandt, Thorsten; Fellmuth, B.

doi:10.1088/0026-1394/52/5/s217

Cited by 84 publications

(127 citation statements)

References 36 publications

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“…Based on these results, and thanks to the resolving of a discrepancy between the values of LNE-11 and NPL-13 20 , the uncertainty of the 2014 adjusted value of k has been significantly reduced to 5.7 parts in 10 7 . Experiments using dielectric-constant gas thermometry developed at PTB (PhysikalischTechnische Bundesanstalt, Germany) 21 and noise thermometry at NIM (National Institute of Metrology, China) 22 achieved uncertainties close to 4 parts in 10 6 . These two experiments are certainly candidates for meeting the second CCT requirement 23 .…”

Section: Requirements For the Defining Constantsmentioning

confidence: 99%

The new system of units

Fischer

Ullrich

2016

Nature Phys

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Section: Requirements For the Defining Constantsmentioning

confidence: 99%

The new system of units

Fischer

Ullrich

2016

Nature Phys

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“…The metal foil resistors have thickness t ≈ 0.025 mm or less, so that t/δs << 1 within our bandwidth. In this limit, the expected skin-effect frequency dependence of a foil resistor is very weak, and the first real nonvanishing term in an expansion in powers of t/δs would be of order (t/2δs) 4 , which is proportional to f 2 . Again, we would expect that the skin-effect contributions to the observed frequency dependence in the ratio spectrum are small and indistinguishable from larger terms already accounted for in the model.…”

Section: Frequency Dependencementioning

confidence: 99%

“…An alternative technique using dielectric constant gas thermometry [4,5] recently produced a value for k with a relative uncertainty of 1.9 × 10 −6 [6]. The combination of these two techniques meets the CCT requirement for redefinition.…”

Section: Introductionmentioning

confidence: 99%

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The NIST Johnson Noise Thermometry System for the Determination of the Boltzmann Constant

Flowers-Jacobs

Pollarolo

Coakley

et al. 2017

J. RES. NATL. INST. STAN.

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In preparation for the redefinition of the International System of Units (SI), five different electronic measurements of the Boltzmann constant have been performed using different Johnson noise thermometry (JNT) systems over the past seven years. In this paper, we describe in detail the JNT system and uncertainty components associated with the most recent National Institute of Standards and Technology (NIST) determination of the Boltzmann constant: k = 1.380642 9(69) × 10 −23 J/K, with a relative standard uncertainty of 5.0 × 10 −6 and relative offset of −4.05 × 10 −6 from the Committee on Data for Science and Technology (CODATA) 2014 recommended value. We discuss the input circuits and the approach we used to match the frequency response of two noise sources. We present new measurements of the correlated noise of the 4 K on-chip resistors in the quantum-accurate, pseudorandom, voltagenoise source, which we used to estimate the correlated, frequency-dependent, nonthermal noise in our system. Finally, we contrast our system with those used in other measurements and speculate on future improvements.

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“…Among primary methods, important advancements [2] have been obtained over the past decade on dielectric constant gas thermometry and Johnson noise thermometry [3,4]. After a first successful experiment of Doppler-broadening thermometry (DBT) [5], followed by significant improvements [6,7], the international community of fundamental metrology recognized the importance of an optical method that links the thermodynamic temperature to an optical frequency, as an independent confirmation of other primary approaches.…”

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confidence: 99%

Cavity-ring-down Doppler-broadening primary thermometry

et al. 2018

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A step forward in Doppler-broadening thermometry is demonstrated using a comb-assisted cavity-ring-down spectroscopic approach applied to an isolated near-infrared line of carbon dioxide at thermodynamic equilibrium. Specifically, the line-shape of the P e (12) line of the (30012) ← (00001) band of CO 2 at 1.578 µm is accurately measured and its Doppler width extracted from a refined multispectrum fitting procedure accounting for the speed dependence of the relaxation rates, which were found to play a role even at the very low pressures explored, from 1 to 7 Pa. The thermodynamic gas temperature is retrieved with relative uncertainties of 8 × 10 −6 (type A) and 11 × 10 −6 (type B), which ranks the system at the first place among optical methods. Thanks to a measurement time of only ≈5 h, the technique represents a promising pathway toward the optical determination of the thermodynamic temperature with a global uncertainty at the 10 −6 level.DOI: 10.1103/PhysRevA.97.012512The forthcoming redefinition of the unit kelvin [1], in 2018, in terms of a fixed value of the Boltzmann constant, prompts the interest for primary thermometers that are capable to operate over a relatively large part of the temperature scale with very high accuracy. Among primary methods, important advancements [2] have been obtained over the past decade on dielectric constant gas thermometry and Johnson noise thermometry [3,4]. After a first successful experiment of Doppler-broadening thermometry (DBT) [5], followed by significant improvements [6,7], the international community of fundamental metrology recognized the importance of an optical method that links the thermodynamic temperature to an optical frequency, as an independent confirmation of other primary approaches.DBT consists of retrieving the Doppler width ν D from the highly accurate observation of the shape of a given atomic or molecular line, in a laser-based absorption-spectroscopy experiment under a linear regime of radiation-matter interaction [8]. Once ν D is measured, if the central frequency (ν 0 ) and the atomic or molecular mass (M) are known, the inversion of the well-known equationallows one to determine the thermal energy and, consequently, either the gas temperature (T ) or the Boltzmann constant (k B ). So far, the most accurate implementation of DBT has been performed on a rovibrational transition of a water isotopologue at 1.39 µm. Using a dual-laser spectrometer and adopting a very sophisticated spectral analysis procedure, the Boltzmann constant could be determined with a combined uncertainty of 24 parts per million (ppm) [6,9,10].The history of DBT [11] shows that the major hurdle for a low-uncertainty determination of the Doppler width and hence of the thermal energy is the choice of the line-shape model adopted for the spectral analysis. Since a fully ab initio lineshape calculation is prohibitively complex for self-colliding molecules, a model suitable for being implemented into a fitting routine requires approximations and simplifications. At the same time, th...

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Dielectric-constant gas thermometry

Cited by 84 publications

References 36 publications

The new system of units

The new system of units

The NIST Johnson Noise Thermometry System for the Determination of the Boltzmann Constant

Cavity-ring-down Doppler-broadening primary thermometry

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