Angular distribution of photons for the simultaneous excitation and ionization of He-like uranium ions in relativistic ion-atom collisions

作者：Salem S^*; Stoehlker Th; Braeuning Demian A; Hagmann S; Kozhuharov C; Liesen D; Gumberidze A

来源：Physical Review A, 2013, 88(1): 012701.

DOI：10.1103/PhysRevA.88.012701

Simultaneous ionization and excitation processes are studied for initially He-like uranium ions in collisions with xenon gaseous targets at relativistic energy, 220 MeV/u. The virtue of investigating the process of simultaneous excitation and ionization is that one electron ends up in the continuum, while the other electron ends up in a hydrogen-like final state. Experimentally, this process can be identified by observing the radiative decay of the excited levels in coincidence with ions that lost one electron (U91+). In particular, owing to the large fine-structure splitting of H-like U, the angular distribution of photons for the simultaneous ionization and excitation into the different total angular momentum j = 1/2 and j = 3/2 states of the L shell is determined directly from the observed yields of Ly(alpha 1) and Ly(alpha 2) radiation at various observation angles. The experimental data show a progress for the dependence of the alignment on the collision impact parameter. It is shown that the current results confirm the theoretical predictions based on the independent-particle approximation and first-order perturbation, for which the simultaneous ionization and excitation processes occur at small impact parameter.

• 出版日期2013-7-2