We employ the impulse approximation for description of positronium-atom
scattering. Our analysis and calculations of Ps-Kr and Ps-Ar collisions provide
theoretical explanation of the similarity between the cross sections for
positronium scattering and electron scattering for a range of atomic and
molecular targets observed by S. J. Brawley et al. [Science 330, 789 (2010)].Comment: 10 pages, 3 figure