“…The Ps-formation DCS near the forward direction has been recently measured for positron collisions for a number of targets including helium [4][5][6]. While a dip was found in the measured near-forward direction Ps-formation DCS for positron collisions from Ne, Ar, Kr and Xe [5], it was not observed in the cross section for positron-helium collisions for the energy range of the experiment [4,6]. However, we theoretically obtained a minimum in the Ps-formation DCS (θ = 0 • ) for positron-helium collisions at 17.9 eV, which is at a lower energy than the energies considered in the experiment for helium [4,6].…”