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  • NPL to provide Caesium Fountain clock to CERN

NPL to provide Caesium Fountain clock to CERN

The NPL caesium fountain primary frequency standard apparatus is used to realise the SI definition of the second and contributes to the construction of the international time scale, UTC.

NPL supplies caesium fountain primary frequency standards to other national standards laboratories or organisations needing direct reference to a realisation of the SI second, such as time distribution centres and large scientific facilities. The standard is also useful to observatories which require precise timing for astronomical observations and satellite laser ranging.

NPL is now working to build and install a caesium fountain clock for the ALPHA experiment at CERN.  

ALPHA (Antihydrogen Laser Physics Apparatus) is an international collaboration based at CERN, working with trapped antihydrogen atoms, the antimatter counterpart of the simplest atom, hydrogen. Their mission is to use ultra-precise spectroscopy to uncover, as yet unseen, differences between matter and antimatter.

The ultimate goal is to measure the energy level structure of the antihydrogen system when excited with lasers. This has been successful achieved by the collaboration in the past however the precision of the measurement will soon be limited by the knowledge of the frequency of the laser applied during the experiment.

A frequency standard reference, provided by the NPL built caesium fountain, will be used to calibrate the measurement and provide the increased accuracy required by the team. The frequency standard reference for ALPHA is funded by the EPSRC and the Carlsberg Foundation.

30 Nov 2020