München 2004 – scientific programme
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A: Atomphysik
A 10: Atomspektroskopie I
A 10.2: Talk
Tuesday, March 23, 2004, 14:45–15:00, HS 133
Recent Improvements of Cs Fountain Clocks at BNM-SYRTE — •Peter Rosenbusch1, Sebastian Bize1, Luigi Cacciapuoti1, Harold Marion1, Franck Pereira dos Santos1, Giorgio Santarelli1, Celine Vian1, Shougang Zhang1, Andre Clairon1, Servaas Kokkelmans2, and Christophe Salomon2 — 1BNM-SYRTE, Observatoire de Paris, 61 Av. de l’Observatoire, 75014 Paris, France — 2Laboratoire Kastler Brossel, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris, France
To date atomic fountain clocks using laser cooled Cs atoms prove to be the most accurate frequency standards. Among the three set-ups at BNM-SYRTE, FO1 has recently undergone substantial changes. The cold atom preparation has been entirely rebuilt. An optical molasses is directly loaded from a slowed atomic beam making a magneto-optical trap redundant. Furthermore, the lower density of the cold atom cloud reduces inter-atomic collisions. We load typically 108 atoms at a temperature of 1 µK. By (111)-moving molasses the atoms are launched with ∼ 4 m/s into the selection and interaction region. Selection of the F=3 mF=0 state can be carried out by adiabatic passage allowing the preparation of 100% or 50% of the atoms. This allows quantifying the collisional shift to a precision of 10−16 [1]. Preparation of some additional atoms in other mF levels can lead to a strong dependence of the collisional shift on the magnetic field even if the latter is only of the order of 1 mG. We present measurements taken on FO2 demonstrating this Feshbach-resonance like behaviour.
[1] F. Pereira Dos Santos et al, Phys. Rev. Lett. 89, 233004 (2002)