S.M. Osadchy, B.G. Potapov, K.D. Pilipenko Al’manac of Modern Metrology № 4 (12) 2017, pages 15–42 The frequencies of  acoustic and microwave  resonanse of a quasi-spherical acoustic resonator filled with helium have been measured at the temperature of triple point of water. Resonator maintained near the temperature of the triple point of water and filled with … Continue reading Acoustic gas thermometer for implementation of the new definition of Kelvin on the basis of fundamental physical constant of Boltzmann