The international Boltzmann project – the contribution of the PTB

Fellmuth, B.; Fischer, Joachim; Gaiser, Christof; Priruenrom, Tasanee; Sabuga, Wladimir; Ulbig, Peter

doi:10.1016/j.crhy.2009.10.012

Cited by 5 publications

(4 citation statements)

References 25 publications

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“…From the present paper, a correction due to the hyperfine structure of the probed rovibrational line needs to be applied. This correction is of -8.71(3) ppm leading to a refined determination of ( ) 23 , within 39 ppm [15]. The detailed comparison between the Voigt and the Galatry profile convinced us that the residual error will be reduced at the ppm level if the pressure in the absorption chamber stays below 0.5 Pa.…”

Section: Discussionmentioning

confidence: 87%

“…− × [15]. Besides some projects following Moldover's approach [16][17][18][19], an alternative approach based on the virial expansion of the Clausius-Mossotti equation and measurement of the permittivity of helium is very promising [20][21][22][23][24][25]. Since 2004 we have developed a new approach based on laser spectroscopy in which B k is determined by a frequency measurement.…”

Section: Introductionmentioning

confidence: 99%

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Progress towards an accurate determination of the Boltzmann constant by Doppler spectroscopy

et al. 2011

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In this paper, we present significant progress performed on an experiment dedicated to the determination of the Boltzmann constant, B k , by accurately measuring the Doppler absorption profile of a line in a gas of ammonia at thermal equilibrium. This optical method based on the first principles of statistical mechanics is an alternative to the acoustical method which has led to the unique determination of B k published by the CODATA with a relative accuracy of 6 1 7 10 . − × . We report on the first measurement of the Boltzmann constant by laser spectroscopy with a statistical uncertainty below 10 ppm, more specifically 6.4 ppm. This progress results from improvements in the detection method and in the statistical treatment of the data. In addition, we have recorded the hyperfine structure of the probed ν2 saQ(6,3) rovibrational line of ammonia by saturation spectroscopy and thus determine very precisely the induced 4.36 (2) ppm broadening of the absorption linewidth. We also show that, in our well chosen experimental conditions, saturation effects have a negligible impact on the linewidth. Finally, we draw the route to future developments for an absolute determination of B k with an accuracy of a few ppm.

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Section: Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Progress towards an accurate determination of the Boltzmann constant by Doppler spectroscopy

et al. 2011

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“…T1.J1.4), PTB designed a new DCGT experimental setup. This decision has been taken in view of the excellent experimental DCGT results that were obtained in the low-temperature range [3,[10][11][12][13] and allowed a thermodynamic temperature scale to be set up between 2.5 K and 36 K.…”

Section: Introductionmentioning

confidence: 99%

Determination of the Boltzmann constant by dielectric-constant gas thermometry

et al. 2011

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Within an international project directed to the new definition of the base unit kelvin, the Boltzmann constant k has been determined by dielectric-constant gas thermometry at PTB. In the pressure range from about 1 MPa to 7 MPa, 11 helium isotherms have been measured at the triple point of water (TPW) by applying a new special experimental setup consisting of a large-volume thermostat, a vacuum-isolated measuring system, stainless-steel 10 pF cylindrical capacitors, an autotransformer ratio capacitance bridge, a high-purity gas-handling system including a mass spectrometer, and traceably calibrated special pressure balances with piston–cylinder assemblies having effective areas of 2 cm2. The value of k has been deduced from the linear, ideal-gas term of an appropriate virial expansion fitted to the combined isotherms. A detailed uncertainty budget has been established by performing Monte Carlo simulations. The main uncertainty components result from the measurement of pressure and capacitance as well as the influence of the effective compressibility of the measuring capacitor and impurities contained in the helium gas. The combination of the results obtained at the TPW (kTPW = 1.380 654 × 10−23 J K−1, relative standard uncertainty 9.2 parts per million) with data measured earlier at low temperatures (21 K to 27 K, kLT = 1.380 657 × 10−23 J K−1, 15.9 parts per million) has yielded a value of k = 1.380 655 × 10−23 J K−1 with uncertainty of 7.9 parts per million.

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“…T1.J1.4), PTB designed a new DCGT experimental setup. This decision has been taken in view of the excellent experimental DCGT results, which were obtained in the low-temperature range [3,10,11,12,13] and allowed to set up a thermodynamic temperature scale between 2.5 K and 36 K.…”

Section: Introductionmentioning

confidence: 99%