CCTF-2017-Recommendation-2

Recommendation 2 of the 21st CCTF (2017)

Updates to the CIPM list of standard frequencies

The Consultative Committee for Time and Frequency (CCTF), at its 21st session in 2017,

considering that

  • a common list of “Recommended values of standard frequencies for applications including the practical realization of the metre and secondary representations of the second” has been established,
  • the CCL-CCTF Frequency Standards Working Group (WGFS) has reviewed several candidates for updating the list;

recommends that

the following transition frequencies shall be updated in the list of recommended values of standard frequencies:

  • the unperturbed optical transition 5s2 1S0 – 5s5p 3P0 of the 115In+ ion with a frequency of f115In+ = 1 267 402 452 901 050 Hz and an estimated relative standard uncertainty of 1.6 × 10–14;
  • the unperturbed optical transition 6s2 1S0 – 6s6p 3P0 of the 199Hg neutral atom with a frequency of f199Hg = 1 128 575 290 808 154.4 Hz and an estimated relative standard uncertainty of 5 × 10–16;
    This radiation is now endorsed as a secondary representation of the second;
  • the unperturbed optical transition 6s2 1S0 – 6s6p 3P0 of the 171Yb neutral atom with a frequency of f171Yb = 518 295 836 590 863.6 Hz and an estimated relative standard uncertainty of 5 × 10–16 (this radiation is already endorsed by the CIPM as a secondary representation of the second);
  • the unperturbed optical transition 5s 2S1/2 – 4d 2D5/2 of the 88Sr+ ion with a frequency of f88Sr+ = 444 779 044 095 486.5 Hz and an estimated relative standard uncertainty of 1.5 × 10–15 (this radiation is already endorsed by the CIPM as a secondary representation of the second);
  • the unperturbed optical transition 5s2 1S0 – 5s5p 3P0 of the 88Sr neutral atom with a frequency of f88Sr = 429 228 066 418 007.0 Hz and an estimated relative standard uncertainty of 6 × 10−16;
  • the unperturbed optical transition 5s2 1S0 – 5s5p 3P0 of the 87Sr neutral atom with a frequency of f87Sr = 429 228 004 229 873.0 Hz and an estimated relative standard uncertainty of 4 × 10–16 (this radiation is already endorsed by the CIPM as a secondary representation of the second);
  • the unperturbed optical transition 4s 2S1/2 – 3d 2D5/2 of the 40Ca+ ion with a frequency of f40Ca+ = 411 042 129 776 399.8 Hz and an estimated relative standard uncertainty of 2.4 × 10–15;
  • the unperturbed ground-state hyperfine transition of 87Rb with a frequency of f87Rb = 6 834 682 610.904 312 6 Hz and an estimated relative standard uncertainty of 6 × 10−16 (this radiation is already endorsed by the CIPM as a secondary representation of the second);

and informs the CIPM accordingly.

reference The reader should note that the official version of this Resolution is the French text

for more details - standard frequencies BUTTON

CCTF logo

Navigation Menu