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24 maja 2018 o godzinie 12:30 w sali audytoryjnej COK w Instytucie Fizyki UMKprof. dr hab. Bogumił Jeziorski (Uniwersytet Warszawski) wygłosi wykład pt.„Teoretyczne wyznaczanie właściwości helu na potrzeby nowych standardów ciśnienia i temperatury”. 


In November this year the General Conference on Weights and Measures will ratify the re-definition of basic SI units, that will be formally implemented on World Metrology Day, May 20, 2019. Specifically the new kilogram will be defined by fixing the numerical value of the Planck constant and the new kelvin by fixing the Boltzmann constant. The exact values of these constants, to be ratified in November, will be close to the best values measured thus far using the old SI units. The new definitions of pascal and kelvin, will call for new, more accurate primary pressure and temperature standards [1]. In this talk I will present very accurate calcu-lations of the polarizability, the two-body interaction potential, and thermophysical properties of helium that were employed to obtain the current most precise value of the Boltzmann con-stant and that will be used to define a new, quantum based pressure standard and to improve primary temperature standards. The high accuracy demanded by the metrological application requires determination of the relativistic, quantum electrodynamics, and nonadiabatic coupling effects with reliable error control and uncertainty estimates. Recent results of such calculations of the dynamic polarizability [2, 3] and the pair potential [4, 5] of helium will be presented and discussed.

[1]    M. R. Moldover, W. L. Tew and H. W. Yoon, Nature Phys. 12, 7 (2016).
[2]    K. Piszczatowski, M. Puchalski, J. Komasa, B. Jeziorski and K. Szalewicz, Phys. Rev. Lett. 114, 173004 (2015).
[3]    M. Puchalski, K. Piszczatowski, J. Komasa, B. Jeziorski and K. Szalewicz, Phys. Rev. A 93, 032515 (2016).
[4]    M. Przybytek, B. Jeziorski, W. Cencek, J. Komasa, J. Mehl and K. Szalewicz, Phys. Rev. Lett. 108, 183201 (2012).
[5]    M. Przybytek, W. Cencek, B. Jeziorski and K. Szalewicz, Phys. Rev. Lett. 119, 123401 (2017).

 Organizatorem kolokwium jest Instytut Fizyki UMK.

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