Title :
Cs and Rb fountains
Author :
Lemonde, P. ; Bize, S. ; Sortais, Y. ; Abgrall, M. ; Zhang, S. ; Calonico, D. ; Marion, H. ; Macsimovic, Y. ; Laurent, P. ; Santarelli, G. ; Luiten, A. ; Tobar, M. ; Salomon, C. ; Clairon, A.
Author_Institution :
BNM-SYRTE, Obs. de Paris, France
Abstract :
We discuss the present performance and limits of our Cs and Rb fountains. BNM-SYRTE operates three cold atom microwave fountains: two Cs fountains and a dual Cs-Rb fountain. By using an ultra-stable cryogenic sapphire oscillator to probe the atoms, the frequency stability reaches 3.5 /spl times/ 10/sup -14//spl tau//sup -1/2/ which will allow an improvement of the accuracy below the present 10/sup -15/. We discuss here the problems to be solved for reaching a 10/sup -16/ accuracy. We also use the fountains to test the stability of the fine structure constant. Measurements of the ratio v/sub Rb//v/sub Cs/ spread over a two year interval show no change of a at the 7 /spl times/ 10/sup -15//year level.
Keywords :
atomic clocks; caesium; frequency stability; rubidium; Cs; Cs fountain; Rb; Rb fountain; accuracy; cold atom microwave fountain; dual Cs-Rb fountain; fine structure constant; frequency stability; ultra-stable cryogenic sapphire oscillator; Clocks; Cryogenics; Frequency; Hydrogen; Masers; Oscillators; Phase noise; Stability; Synthesizers; Testing;
Conference_Titel :
Precision Electromagnetic Measurements, 2002. Conference Digest 2002 Conference on
Conference_Location :
Ottawa, Ontario, Canada
Print_ISBN :
0-7803-7242-5
DOI :
10.1109/CPEM.2002.1034914
