Production of collimated positronium by positron scattering from CO2, N2 and Xe M. Shipman, S. Brawley, D.E. Leslie, S. Armitage and G. Laricchia Eur. Phys. J. D, 66 4 (2012) 96 Published online: 19 April 2012 DOI: 10.1140/epjd/e2012-20753-9