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

The kinetics of metastable states of exotic antiproton helium atoms ('atomcules') illuminated with a series of laser π pulses, which are resonant with adjacent transitions forming a cascade, is numerically studied. It is shown that the phenomena taking place in this case can be used to study the mechanisms responsible for the depletion of the high-n states, measure populations of individual metastable energy levels, and slow down the decay of the system under study by way of inverting the populations with a train of π pulses