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The elastic scattering differential cross sections (EDCS) for e$^+$-H and e$^+$-He below the first excitation threshold of the target are found to be very similar. They are evaluated using the Kohn variational method and both the individual partial wave contributions and their sum are very well converged. In both cases the EDCS below the Ps formation threshold, i.e. for pure elastic scattering, has a minima valley feature in which a significant minimum close to 90 degrees is found at $\approx$ 2.8 eV for H and $\approx$ 2 eV for He. These minima are shown not be vortices but to be related to the vortices found in the Ps formation differential cross sections just above the Ps formation threshold [1, 2]. We show that the valley type structure in the EDCS goes smoothly through the Ps formation threshold, linking up with a similar valley structure in both the EDCS above the threshold and the Ps formation DCS in which vortices have been found [1, 2].
[1] A.W. Alrowaily, S. J. Ward, and P. Van Reeth, J. Phys. B 52, 205201 (2019)
[2] A.W. Alrowaily, S. J. Ward, and P. Van Reeth, Atoms 9(3) (2021)