Atomic Physics Workshop

V.V. Balashov, Moscow State University

Coherent and incoherent interactions of channeled highly charged ions with crystals

We present our latest results and their relation to current experimental studies on channeling and resonant coherent excitation (RCE) of fast highly charged ions in oriented crystals the Okorokov effect [1]). A specific feature of their theoretical description is that both coherent and incoherent aspects of the ion-matter interactions are here of equal importance. Therefore neither Pauli rate equation nor Schroedinger wave function description could be an adequate instrument to proceed. We consider a channeled ion as an open quantum system and, following [2], base our approach on the generalized Master equation for the density matrix of the channeled ion to describe evolution of its electron shell in course of ion passage through the periodic structure of the target. Curvilinear character of the ion trajectory, splitting of its levels in the combined lattice and polarization wake potential, thermal vibrations of the lattice and incoherent interactions between the moving ion and its surrounding leading to ion charge exchange processes and relaxation of its resonance excitations are taken into consideration together. Theoretical calculations are performed to: (a) the resonance profile in the ion velocity dependence of the survival fraction of the initial charge state of the incoming ion; (b) the resonance yield of characteristic X-ray radiation of channeled ions and its possible angular anisotropy coursed by alignment of the excited ion produced in course of its passage through the target; (b) metastable ion production in the RCE process. Their results are considered on the background of current experimental studies on interaction of fast highly charged ions with crystals.

[1] V.V. Okorokov, Yad. Fiz. 2 (1965) 1009; Sov. J. Nucl. Phys. 2 (1966) 719; Pis'ma Zh. Eksp. Teor. Fiz. 2 (1965) 175.

[2] V.V. Balashov, I.V. Bodrenko, Moscow State University Bulletin, Physics and Astronomy, Number 1 (2001) 27.