Open Access

Alexandre Gumberidze, Daniel B. Thorn, Andrey Surzhykov, Christopher J. Fontes, Dariusz Banaś, Heinrich F. Beyer, Weidong Chen, Robert Evaristo Grisenti, Siegbert Hagmann, Regina Hess, Pierre-Michel Hillenbrand, Paul Indelicato, Christophor Kozhuharov, Michael Lestinsky, Renate Märtin, Nikolaos Petridis, Roman V. Popov, Reinhold Schuch, Uwe Spillmann, Stanislav Tashenov, Sergiy Trotsenko, Andrzej Warczak, Günter Weber, Weiqiang Wen, Danyal Ferdinant Alexander Winters, Natalya Winters, Zhong Yin, Thomas Stöhlker

• In this paper, we present an experimental and theoretical study of excitation processes for the heaviest stable helium-like ion, that is, He-like uranium occurring in relativistic collisions with hydrogen and argon targets. In particular, we concentrate on angular distributions of the characteristic Kα radiation following the K → L excitation of He-like uranium. We pay special attention to the magnetic sub-level population of the excited 1s2lj states, which is directly related to the angular distribution of the characteristic Kα radiation. We show that the experimental data can be well described by calculations taking into account the excitation by the target nucleus as well as by the target electrons. Moreover, we demonstrate for the first time an important influence of the electron-impact excitation process on the angular distributions of the Kα radiation produced by excitation of He-like uranium in collisions with different targets.