학술논문
X-ray emission associated with radiative recombination for Pb$^{82+}$ ions at threshold energies
Document Type
Working Paper
Author
Zhu, B.; Gumberidze, A.; Over, T.; Weber, G.; Andelkovic, Z.; Bräuning-Demian, A.; Chen, R.; Dmytriiev, D.; Forstner, O.; Hahn, C.; Herfurth, F.; Herdrich, M. O.; Hillenbrand, P. -M.; Kalinin, A.; Kröger, F. M.; Lestinsky, M.; Litvinov, Y. A.; Menz, E. B.; Middents, W.; Morgenroth, T.; Petridis, N.; Pfäfflein, Ph.; Sanjari, M. S.; Sidhu, R. S.; Spillmann, U.; Schuch, R.; Schippers, S.; Trotsenko, S.; Varga, L.; Vorobyev, G.; Stöhlker, Th.
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Subject
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Abstract
For bare lead ions, decelerated to the low beam energy of 10 MeV/u, the x-ray emission associated with radiative recombination (RR) at "cold collision" conditions has been studied at the electron cooler of CRYRING@ESR at GSI-Darmstadt. Utilizing dedicated x-ray detection chambers installed at 0{\deg} and 180{\deg} observation geometry, we observed for the very first time for stored ions the full x-ray emission spectrum associated with RR under electron cooling conditions. Most remarkably, no line distortion effects due to delayed emission are present in the well resolved spectra, spanning over a wide range of x-ray energies (from about 5 to 100 keV) which enable to identify fine-structure resolved Lyman, Balmer as well as Paschen x-ray lines along with the RR transitions into the K-, L and M-shell of the ions. To compare with theory, an elaborate theoretical model has been applied. By considering the relativistic atomic structure of Pb$^{81+}$, this model is based on a sophisticated computation of the initial population distribution via RR for all atomic levels up to Rydberg states with principal quantum number $n=$ 165 in combination with cascade calculations based on time-dependent rate equations. Within the statistical accuracy, the experimental x-ray line emission is in very good agreement with the results of the theoretical model applied. Most notably, this comparison sheds light on the contribution of prompt and delayed X-ray emission (up to 70 ns) to the observed X-ray spectra, originating in particular from Yrast transitions into inner shells.