LASER STUDIES OF THE DECAY CHAIN OF METASTABLE ANTIPROTONIC HELIUM-ATOMS

Laser studies of metastable antiprotonic helium atoms, which we recent ly initiated by observing a sharp increase of the antiproton annihilat ion rate induced by laser-stimulated resonant transitions, have been e xtended. With a single laser tuned to the resonance already found at 5 97.26 nm, we have now established the time dependence of the upper sta te population. With two lasers ignited at variable time separation, we also studied the feeding of the upper state from higher atomic levels . The initial populations and level lifetimes of excited exotic atoms were determined.