Spectroscopy of the hyperfine structure of antiprotonic 4He and 3He

摘要

The spin magnetic moment m[`(p)]<sub>s</sub>mu^{overline{p}}_{s} of the antiproton can be determined by comparing the measured transition frequencies in [`(p)]4overline{p}^4He + with three-body QED calculations. A comparison between the proton and antiproton can then be used as a test of CPT invariance. The highest measurement precision of the difference between the proton and the antiproton spin magnetic moments to date is 0.3%. A new experimental value of the spin magnetic moment of the antiproton was obtained as m[`(p)]<sub>s</sub> = -2.7862(83)m<sub>N</sub>mu^{overline{p}}_{s} = -2.7862(83)mu_{N}, slightly better than the previously best measurement. This agrees with mp<sub>s</sub>mu^{p}_{s} within 0.24%. In 2009, a new measurement with antiprotonic 3He has been started. A comparison between the theoretical calculations and experimental results would lead to a stronger test of the theory and address systematic errors therein. A measurement of this state will be the first HF measurement on [`(p)]3overline{p}^3He + . We report here on the new experimental setup and the first tests.