  We explore the possibility of decelerating and Doppler cooling an ensemble of
tree-level $\Lambda$-type atoms by a coherent train of short, non-overlapping
laser pulses. We show that $\Lambda$-atoms can be Doppler cooled without
additional repumping of the population from the intermediate ground state. We
derive analytical expression for the scattering force in the quasi-steady-state
regime and analyze its dependence on pulse train parameters. Based on this
analysis we propose a method of choosing pulse train parameters to optimize the
cooling process.

Atomic Physics