Hyperfine structure of metastable antiprotonic helium atomcules

The measurement of hyperfine structures in antiprotonic helium atomcules is an important step in improving the precision already achieved by the PS205 collaboration in laser-spectroscopy of these exotic atoms. This paper describes the first observation of a line splitting in a laser-induced transition, and discusses the prospect of direct measurements of level splittings using a micro-wave technique, which may ultimately lead to a precise determination of the antiproton magnetic moment. (orig.)