Radiative electron capture in relativistic ion–atom collisions and the photoelectric effect in hydrogen-like high-Z systems

Angular and polarization analysis of x-rays emitted from highly-charged, few-electron ions

“…From the angular distribution and polarization of the emitted photons, for example, valuable information was obtained about the relativistic and magnetic-interaction effects [3,4] as well as the multipole-mixing in the coupling of high-Z ions to the radiation field [5]. Up to the present, however, most of the angleand polarization-resolved experiments have been performed for the REC into initially bare ions and were found in very good agreement with computations, based on Dirac's equation and the density matrix theory [2,5,6,7,8]. For the capture into few-electron ions, first measurements were carried out only recently [9,10] but are expected to provide additional information about the interplay of the electron-photon and electron-electron interactions.…”

“…Hereby, one of the main goals in studying the structure and dynamics of simple atomic systems is to understand the photon-matter interaction in the largely unexplored domain of relativistic collision energies and strong nuclear fields. Among several other processes, in particular the radiative electron capture (REC) of target electrons into the bound states of fast-moving projectile ions has attracted much recent interest [1,2], because it enables one to explore the interplay between the electron-photon and electronelectron interactions in the presence of strong fields. In addition, the knowledge of the REC cross sections is important also for the design of novel accelerators and ion storage rings since, for relativistic energies, this charge-transfer process is known to be dominant and leads to the loss of ions from the beam.…”

Two-photon decay in highly charged heavy ions: Spectral shape of the 2E1 (21S0→ 11S0) in He-like tin

“…The experiment was performed at the storage ring ESR with 300 MeV/u Li-like tin ions colliding with a nitrogen gas-jet target [11] under single collision conditions. A schematic view of the ESR storage ring and the experimental setup at the target area is depicted in Fig.…”

“…Typical experimental arrangement at the gas-jet target of the storage ring ESR [11]. Near to the target, the ion/gas-jet collision zone is surrounding by an array of solid state detectors.…”

“…But although these measurements verified all the general trends in the two-photon emission, they were not (yet) able to test the predictions from the relativistic theory due to the lack of accuracy, the low statistics as well as a number of further experimental difficulties. showing the electron cooler, the gasjet target, particle detector and several other components [11].…”