Formation of light antinuclei and "dense gas" stage in heavy ion collisions

The antideuteron and antihelium-3 production rates at high-energy heavy ion collisions are calculated in the framework of fusion mechanism when participating particles are moving in the mean field of other fireball constituents. It is shown that coalescence parameters can be found from the requirement of balance between created and disintegrated antinuclei. The explicit formulae for coalescence parameters are presented and compared with experimental data.