  When high-intensity laser interaction with matter enters the regime of
dominated radiation reaction, the radiation losses open the way for producing
short pulse high power gamma ray flashes. The gamma-ray pulse duration and
divergence are determined by the laser pulse amplitude and by the plasma target
density scale length. On the basis of theoretical analysis and particle-in-cell
simulations with the radiation friction force incorporated, optimal conditions
for generating a gamma-ray flash with a tailored overcritical density target
are found.
