Accession Number : ADP002449

Title :   Mercury-199 Trapped Ion Frequency Standard. Recent Theoretical Progress and Experimental Results,


Personal Author(s) : Cutler,L. S. ; Giffard,R. P. ; McGuire,M. D.

Report Date : 1983

Pagination or Media Count : 5

Abstract : The 40.5 GHz hyperfine resonance of 199 Hg ions stored in an rf quadrupole trap has shown to have a very small fractional linewidth, suggesting its use as a high-precision frequency standard. The most significant offset in such a standard would be the second-order Doppler shift resulting from the motion of the stored ions. We have recently analyzed the situation in which the secular motion is cooled to a temperature of about 300 K by the presence of a light background gas at low pressure, resulting in an ion cloud whose density is almost completely determined by the balance of pseudopotential and space-charge forces. Under these circumstances we have found that the second-order Doppler shift can be calculated accurately from the trapping parameters, the temperature, and the total number and mass of the stored ions.

Descriptors :   *Frequency standards, *Mercury, Ion density, Doppler effect, Helium, Cooling, Resonance

Distribution Statement : APPROVED FOR PUBLIC RELEASE