Abstract
Using a newly developed laser-microwave-laser resonance method, we observed a pair of microwave transitions between hyperfine levels of the state of antiprotonic helium. This experiment confirms the quadruplet hyperfine structure arising from the interaction of the antiproton orbital angular momentum, the electron spin and the antiproton spin as predicted by Bakalov and Korobov. The measured frequencies of and agree with recent theoretical calculations on a level of .
- Received 13 July 2002
DOI:https://doi.org/10.1103/PhysRevLett.89.243402
©2002 American Physical Society