FIRST OBSERVATION OF LASER-INDUCED RESONANT ANNIHILATION IN METASTABLE ANTIPROTONIC HELIUM-ATOMS

We have observed the first laser-induced resonant transitions in antip rotonic helium atoms. These occur between metastable states and Auger dominated short lived states, and show that the anomalous longevity of antiprotons previously observed in helium media results from the form ation of high-n high-l atomic states of He--(p)+. The observed transit ion with vacuum wavelength 597.259 +/- 0.002 nm is tentatively assigne d to (n, l) = (39, 35) --> (38, 34).