Characterization of the Brazilian Cs atomic-frequency standard: evaluation of major shifts

摘要

As part of a programme to implement scientific time and frequency metrology in Brazil, the caesium-beam frequency standard of the Instituto de Fisica de Sao Carlos has been improved in order to obtain greater accuracy. Our most recent evaluation shows an Allan standard deviation of σ_(y)(τ)=(1.8±0.2)×10~(-11)τ~(-0.5), corresponding to an improvement of two orders of magnitude over our previous evaluation. Estimates of the main shifts of the frequency standard, such as second-order Doppler shift, end-to-end cavity phase shift, and Rabi frequency value, have been performed employing two different methods that allow the results to be extracted from the Ramsey pattern.