Radiative Recombination of Highly-Charged Ions with Polarized ElectronsONLINE ONLY

Spin-polarized heavy ion beams are highly relevant for future investigations of the relativistic, QED and PNC phenomena in a domain of high-Z and for the search of new physics beyond the Standard Model [1,2]. The present challenge of storage-ring physics is the production and preservation of polarized ion beams. Radiative recombination (RR) with heavy highly charged ions is an effective tool to product spin-polarized ions in storage rings [3] and to control the polarization transfer to ion [4]. We present the general theory for the spin-polarization transfer between incident electrons and the emitted x-ray photons in the radiative recombination of heavy highly-charged ions, which accounts for arbitrary (longitudinal and/or transversal) polarization of electron beam. In order to investigate how the spin polarization of incident electrons may affect the linear polarization of emitted photons, we apply the density matrix approach and solutions of relativistic Dirac equation. We obtain simple analytical expressions for the dependencies of the differential cross section and the polarization Stokes parameters of RR photons on the components of the incident electrons polarization vector, which allow to analyze the polarization transfer. Based on these expressions, we show that the linear polarization of RR photons is very sensitive to the spin state of an electron target. Detailed calculations have been performed for the capture of the polarized electrons by the bare uranium into the K-shell. The developed theory opens up opportunities for the spin diagnostics of ion beams by means of the analysis of the linear polarization of recombination photon.
 
 
References: 
[1 ]A. Surzhykov, S. Fritzsche, Th  Stöhlker and S. Taschenov, Polarization studies on the radiative recombination of highly charged ions, Phys. Rev. A 68 (2003) 022710.
 
[2] D. Budker, J. R. Crespo López-Urrutia, A. Derevianko, V. V. Flambaum, M. W. Krasny, A. Petrenko, S. Pustelny, A. Surzhykov, V. A. Yerokhin, and M. Zolotorev, Atomic Physics Studies at the Gamma Factory at CERN, Annalen der Physik 532, 2000204 (2020).
 
[3 ]A. Bondarevskaya, E. A. Mistonova, K. N. Lyashchenko, O. Yu. Andreev, A. Surzhykov, L. N. Labzowsky, G. Plunien, D. Liesen, F. Bosch and Th. Stöhlker, Method for the production of highly charged ions with polarized nuclei and zero total electron angular momentum, Phys. Rev. A 90, 064701 (2014).
 
[4] S. Tashenov, Th. Stöhlker, D. Banaś, K. Beckert, P. Beller, H. F. Beyer, F. Bosch, S. Fritzsche, A. Gumberidze, S. Hagmann, C. Kozhuharov, T. Krings, D. Liesen, F. Nolden, D. Protic, D. Sierpowski, U. Spillmann, M. Steck and A. Surzhykov, First measurement of the linear polarization of radiative electron capture transitions, Phys. Rev. Lett. 97, 223202 (2006).