Multipulse laser spectroscopy of antiproton helium: Populations of metastable states and the decay kinetics

The kinetics of metastable states of exotic antiproton helium atoms ("atomc ules") illuminated with a series of laser pi pulses, which are resonant wit h adjacent transitions forming a cascade, is numerically studied. It is sho wn that the phenomena taking place in this case can be used to study the me chanisms responsible for the depletion of the high-n states, measure popula tions of individual metastable energy levels, and slow down the decay of th e system under study by way of inverting the populations with a train of pi pulses.