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Decimal expansion of Δν_{Cs} in unit s^{-1}; one of the seven units of the 2019 SI system.
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%I #52 May 26 2019 15:17:04

%S 9,1,9,2,6,3,1,7,7,0

%N Decimal expansion of Δν_{Cs} in unit s^{-1}; one of the seven units of the 2019 SI system.

%C The second s is defined to be exactly 9192631770 periods of the resonance frequency of the hyperfine transition of the cesium 133 atom.

%C Prime factors of this number are 2^1, 3^2, 5^1, 7^2, 47^1, 44351^1. - _John W. Nicholson_, Jun 15 2014

%C The value was fixed in 1968 by the 13th CGPM in terms of periods of the radiation due to the transition between the two hyperfine levels of the ground state of 133Cs atoms. - _Stanislav Sykora_, Mar 30 2015

%C In the 2019 SI system of units (see the BIPM link, and A322415) one of the seven units is Δν_{Cs} = Δν(^{133}Cs)_{hfs} = 9192631770 s^{-1}. - _Wolfdieter Lang_, Feb 12 2019

%H BIPM, <a href="https://www.bipm.org/utils/common/pdf/CGPM-2018/26th-CGPM-Resolutions.pdf">On the revision of the International System of Units (SI)</a>, BIPM, Nov 13-16 2018.

%H Bureau International des Poids et Mesures, <a href="http://www.bipm.org/en/publications/si-brochure/second.html">Unit of time (second)</a>

%H W. M. Itano and N. F. Ramsey, <a href="http://www.scientificamerican.com/article/accurate-measurement-of-time/">Accurate measurement of time</a>, Scientific American, 269 (July 1993), 56-65.

%H N. F. Ramsey, <a href="http://www.jstor.org/stable/27854962">Precise measurement of time</a>, American Scientist, 76 (No. 1, 1988), 42-49.

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Second">Second</a>

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/2019_redefinition_of_SI_base_units">2019 redefinition of SI base units</a>

%F Δν_{Cs} = 9192631770 s^{-1}.

%e c = 9192631770 m/s.

%t IntegerDigits@ 9192631770 (* _Michael De Vlieger_, Mar 30 2015 *)

%Y Cf. A003678 (c), A003676 (h), A081823 (e), A070063 (k), A322578 (N_A), A244823, A322415.

%K nonn,cons,fini,full

%O 10,1

%A _N. J. A. Sloane_, Oct 19 2013