Cesium fountain primary standard
Fontana al cesio standard di frequenza tempo
In this laboratory, we maintain the Italian primary frequency standard, based on a cesium fountain clock, nitrogen-cooled at 89 K. It has an accuracy of 2 10-16, among the highest ever achieved.

This clock is used for the generation of the Italian timescale and its data are periodically sent to the Bureau International des Poids et Mesures for the computation of the International Atomic Timescale. In addition, this frequency standard is disseminated via optical fiber to several research institutes of the country, to allow precise measurements in atomic and molecular physics at unprecedented resolution.