[en] In our experiment we studied three body momentum correlations of ⁶He breakup products emitted in the quasifree knockout reaction ⁴He(⁶He, 2α) at ⁶He beam energy 25A MeV. For the first time a detailed study of nuclear structure was done in the reaction of quasifree scattering with an unbound system as a spectator. In the experiment we used a detection system of large angular acceptance allowing us to investigate the process in a wide range of kinematical parameters. It was shown that the data obtained in the experiment are well consistent with the predictions obtained with the use of the Plane Wave Impulse Approximation allowing for the final state interaction between the two spectator neutrons.