Measurement of the Barkas effect in hydrogen R. Schmidt, H. Daniel, F.J. Hartmann, P. Hauser, F. Kottmann, M. Mühlbauer, C. Petitjean, W. Schott, D. Taqqu and P. Wojciechowski Eur. Phys. J. D, 3 2 (1998) 119-122 Published online: 15 August 1998 DOI: 10.1007/s100530050155