NIM4 cesium fountain primary frequency standard: performance and evaluation

The NIM4 atomic fountain clock has been operating since August 2003. We in this paper report the experiments certifying its stability of 8E-13//spl tau//sup 1/2/, reproducibility of 5E-15, and present results of the first evaluation for its systematic frequency correction with an uncertainty of 8.5 E-15 during September to December 2003.