Measurement of the Boltzmann Constant k(B) Using a Quasi-Spherical Acoustic Resonator

作者：Pitre Laurent^*; Sparasci Fernando; Truong Daniel; Guillou Arnaud; Risegari Lara; Himbert Marc E

来源：International Journal of Thermophysics, 2011, 32(9): 1825-1886.

DOI：10.1007/s10765-011-1023-x

• Acoustic resonance
• Boltzmann constant
• Definition of the kelvin
• Metrology
• Microwave resonance
• Quasi-sphere
• System of units
• Thermometry
• Triaxial ellipsoid
• Unit of temperature

There is currently great interest in the international metrological community for new accurate determinations of the Boltzmann constant k(B), with the prospect of a new definition of the unit of thermodynamic temperature, the kelvin. In fact, k(B) relates the unit of energy (the joule) to the unit of the thermodynamic temperature (the kelvin). One of the most accurateways to access the value of the Boltzmann constant is from measurements of the velocity of the sound in a noble gas. In the method described here, the experimental determination has been performed in a closed quasi-spherical cavity. To improve the accuracy, all the parameters in the experiment (purity of the gas, static pressure, temperature, exact shape of the cavity monitored by EM microwaves, etc.) have to be carefully controlled. Correction terms have been computed using carefully validated theoretical models, and applied to the acoustic and microwave signals. We report on two sets of isothermal acoustic measurements yielding the value k(B) = 1.380 647 74(171) x 10(-23) J . K-1 with a relative standard uncertainty of 1.24 parts in 10(6). This value lies 1.9 parts in 10(6) below the 2006 CODATA value (Mohr et al., Rev. Mod. Phys. 80, 633 (2008)), but, according to the uncertainties, remains consistent with it.

• 出版日期2011-9