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of the meteorology, composition, and particulate loading of the urban atmosphere in London, United Kingdom, to improve predictive capability for air quality. T he sharply increasing urban population in 2007 exceeded the rural population on a global basis (UN Department of Economic and Social Affairs 2013). Urban populations are exposed to stressful(More)
In the uncertainty budget of primary atomic cesium fountain clocks, evaluations of frequency-pulling shifts of the hyperfine clock transition caused by unintentional excitation of its nearby transitions (Rabi and Ramsey pulling) have been based so far on an approach developed for cesium beam clocks. We re-evaluate this type of frequency pulling in fountain(More)
We describe a measurement of the frequency of the 2 S 1/2 (F = 0)-2 D 3/2 (F = 2) transition of 171 Yb + at the wavelength 436 nm (frequency 688 THz), using a single Yb + ion confined in a Paul trap and two cesium fountains as references. In one of the fountains, the frequency of the microwave oscillator that interrogates the cesium atoms is stabilized by(More)
—We explore the method of rapid adiabatic passage for collisional frequency shift measurements in the primary caesium fountain clock PTB-CSF2 at the Physikalisch-Technische Bundesanstalt (PTB). This method can be used to vary the local density distribution of the atom cloud by exactly a factor of 2. We investigate the performance of the method for different(More)
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