The n=2 triplet P fine structure of atomic helium is being measured using microwave transitions.
The method  of Frequency-Offset Separated Oscillatory Fields (FOSOF) is used to perform
the measurements. The measurement of the J=1-to-J=2 interval has been completed , with a
measurement uncertainty of only 25 Hz. The measurement of the 29.6-GHz J=0-to-J=1 interval
is now being performed. These measurements, together with sufficiently precise theoretical
predictions for the intervals (see  for the current state-of-the-art calculations) can be used to
determine a value for the fine-structure constant and to test for possible physics beyond the
 A. C. Vutha and E. A. Hessels, Phys. Rev. A 92, 052504 (2015).
 K. Kato, T. D. G. Skinner and E. A. Hessels, Phys. Rev. Lett. 121, 143002 (2018).
 K. Pachucki and V. A. Yerokhin, Phys. Rev. Lett. 104, 070403 (2010).
|Presenter name||T. D. G. Skinner|
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