15 research outputs found
Atomic trajectory characterization in a fountain clock based on the spectrum of a hyperfine transition
We describe a new method to determine the position of the atomic cloud during
its interaction with the microwave field in the cavity of a fountain clock. The
positional information is extracted from the spectrum of the F=3,mF=0 to
F=4,mF=-1 hyperfine transition, which shows a position dependent asymmetry when
the magnetic C-field is tilted by a few degrees with respect to the cavity
axis. Analysis of this spectral asymmetry provides the horizontal
center-of-mass position for the ensemble of atoms contributing to frequency
measurements. With an uncertainty on the order of 0.1 mm, the obtained
information is useful for putting limits on the systematic uncertainty due to
distributed cavity phase gradients. The validity of the new method is
demonstrated through experimental evidence.Comment: 6 figures, submitted to PR
Femtosecond frequency comb measurement of absolute frequencies and hyperfine coupling constants in cesium vapor
We report measurements of absolute transition frequencies and hyperfine
coupling constants for the 8S_{1/2}, 9S_{1/2}, 7D_{3/2}, and 7D_{5/2} states in
^{133}Cs vapor. The stepwise excitation through either the 6P_{1/2} or 6P_{3/2}
intermediate state is performed directly with broadband laser light from a
stabilized femtosecond laser optical-frequency comb. The laser beam is split,
counter-propagated and focused into a room-temperature Cs vapor cell. The
repetition rate of the frequency comb is scanned and we detect the fluorescence
on the 7P_{1/2,3/2} -> 6S_{1/2} branches of the decay of the excited states.
The excitations to the different states are isolated by the introduction of
narrow-bandwidth interference filters in the laser beam paths. Using a
nonlinear least-squares method we find measurements of transition frequencies
and hyperfine coupling constants that are in agreement with other recent
measurements for the 8S state and provide improvement by two orders of
magnitude over previously published results for the 9S and 7D states.Comment: 14 pages, 14 figure