THE JPL Hg + EXTENDED LINEAR ION TRAP FREQUENCY STANDARD : STATUS , STABILITY , AND ACCURACY PROSPECTS

Microwave llequency standards based on room temperature ‘~g+ ions in a Linear Ion Trap (LITS) presently achieve a Signal to Noise and line Q inferred short term frequency stability of uY(~)= 2x 10-14/T ln. Long term stability has been measured for averaging intervals up to S months with apparent sensitivity to variations in ion number/temperature limiting the flicker floor to about 5x 10’6 at 100,000 seconds. A two segment version of the linear ion trap (LITE) has also recently demonstrated excellent frequency stability for measurement intewals up to one week. Nearly an order of magnitude improvement in long term stability compared to the LITS is expected since this trap cotilguration operates with reduced linear ion density during the microwave interrogation period.