Progress towards a /sup 133/Cs-fountain as frequency standard in Brazil

Recently, /sup 133/Cs atoms were trapped in a fountain chamber. About 10/sup 8/ cesium atoms are caught in a magneto-optical trap from a vapor cell at room temperature. The "future fountain" has a (1,1,1)-geometry for the laser cooling and launching operation. The difference between this configuration and the usual one concerns the polarization. The three upper beams have the same polarization, in opposition to the three lower ones. The interrogation and preparation cavities were also constructed as well as characterized concerning the temperature tunability in vacuum. The interrogation cavity is made of copper and the quality factor is about 8000. The microwave synthesizer was constructed in collaboration with BNM-SYRTE time and frequency group. The synthesizer was compared to a very stable oscillator at BNM-SYRTE resulting in a short term stability of 9.7/spl times/10/sup -14//spl tau//sup -1/2/.