Single and double over-barrier ionization of He, He+ and Ne system by positron impact Aixiang Yang, Ning Zhang, Binghui Zhu, Xianrong Zou, Ximeng Chen and Jianxiong Shao Eur. Phys. J. D, 71 6 (2017) 170 Published online: 22 June 2017 DOI: 10.1140/epjd/e2017-70500-9