From in-plane to out-of-plane enhancement of the directed flow in ⁶⁴Zn on ⁵⁸Ni collisions between 35 and 79 MeV/u

The azimuthal distributions of light particles relative to the reaction plane have been measured for several bins of experimentally estimated impact parameters in the reactions of ⁶⁴Zn + ⁵⁸Ni at energies between 35 and 79 MeV/u. An in-plane enhancement for mid-rapidity Z = 1, 2, 3 particles is observed at low incident energy but gradually evolves to out-of-plane enhancement (squeeze-out effect) with increasing energy. This evolution depends on the impact parameter in a way similar to the flow parameter. The energies for this system at which the azimuthal distribution is uniform are lower than the corresponding balance energies.