  It is proposed to identify a strong electric field created during relativistic collisions of asymmetric nuclei via observation of pseudorapidity and transverse momentum distributions of hadrons with the same mass but opposite charges. The detailed calculation results for the directed flow within the Parton-Hadron String Dynamics model are given for Cu-Au interactions at the NICA collision energies of $\sqrt{s_{NN}}=9$ and $5$ GeV. The separation effect is observable at 9 GeV as clearly as at 200 GeV 
Evidence for creation of strong electromagnetic fields in relativistic   heavy-ion collisions