A coincidence study of electron and positron impact ionization of Ar (3p) at 1 keVRadu I. Campeanu, James H.R. Walters and Colm T. WhelanEur. Phys. J. D, 69 10 (2015) 235DOI: https://doi.org/10.1140/epjd/e2015-60315-1