Abstract
A femtosecond optical frequency comb and continuous-wave pulse-amplified laser were used to measure 12 transition frequencies of antiprotonic helium to fractional precisions of . One of these is between two states having microsecond-scale lifetimes hitherto unaccessible to our precision laser spectroscopy method. Comparisons with three-body QED calculations yielded an antiproton-to-electron mass ratio of .
- Received 10 April 2006
DOI:https://doi.org/10.1103/PhysRevLett.96.243401
©2006 American Physical Society