Progress towards an operational rubidium fountain

The U.S. Naval Observatory has an ongoing program to develop atomic fountains for eventual incorporation into the USNO Master Clock. The fountains are being constructed to provide a stable frequency reference which will allow for rapid characterization of drift of masers in our clock ensemble. In support of this goal we are using rubidium to exploit the small cold-collision frequency shift. We report on the progress made in the construction and testing of our first rubidium device.cold-collision frequency shift.