Analysis of the Seasonal Effects on Cesium Clocks to Improve the Long- Term Stability of a Time Scale

摘要

The Istituto Elettrotecnico Nazionale time scale UTC(1EN) is generated by a commercial cesium clock selected among the five presently at disposal and is maintained in agreement within 5 microseconds with UTC by means of a phase microstepper. The problem of the influence of the environmental parameters on atomic clocks has been investigated and recent improvements in the international synchronization systems have shown more clearly the presence of seasonal effects on clocks. On the IEN cesium clock ensemble, long term frequency instabilities and seasonal variations have been detected and a relationship between humidity and frequency variations has been analyzed. This investigation has been also extended to the cesium clocks kept in the (ISPT) Laboratory in Roma. An evaluation of the annual repetition of these effects has been performed by means of statistical processes to settle a better use of microstepper corrections and optimize the long term stability of UTC (IEN) time scale.