Case Studies

Since 1967 the SI unit of time, the second, has been defined by caesium atomic clocks. In these, caesium atoms are probed with microwaves at frequencies that cause electrons to ‘jump’ into higher orbitals (~1010 Hz). When this occurs 9 192 631 770 times it defines one second. These clocks have enabled a wide range of modern tec...

To prevent electrical failures in the grid, such as short circuits and breakdowns and resulting blackouts, it is essential that components of the electricity grid, including cabling, insulators, switchgears, and transformers, are tested to ensure suitability for their operating environments. As well as the high voltage alterna...

Waste incineration, steel production, chemical and cement plants all emit hydrogen chloride (HCl) gas which combines with water to produce hydrochloric acid, contributing to photochemical smog that damages health, buildings and ecosystems. The Industrial Emissions Directive (IED) limits maximum permissible HCl emissions from w...

The radiofrequency (RF) part of the electromagnetic spectrum (between 3 kHz and 300 GHz) is used by many current communication systems – including mobile phone networks, TV broadcasting, public radio, and satellites. To reduce interference between these different applications they operate in separate RF “bands” at different fre...

Time and frequency (T&F) reference signals underpin electricity grids, global navigation and the internet. Most applications use signals from orbiting satellites, but their precision is insufficient for advanced research into such things as fundamental physics and quantum technologies. One alternative is to deliver clock signa...

The determination of distances with low measurement uncertainty, linked to the SI, is used in the surveillance of large-scale facilities during construction and the deformation monitoring of critical infrastructures. It is also important in observations of geological hazards, such as volcanoes or tectonic faults and can help ch...