Measurement of electron swarm coefficients in C2F4-Xe and evidence of Penning ionization in C2F4-Ar A. Bekstein, J. de Urquijo, J. L. Hernández-Ávila and E. Basurto Eur. Phys. J. D, 66 3 (2012) 77 Published online: 27 March 2012 DOI: 10.1140/epjd/e2012-20676-5