Polarization effects in radiative recombination of an electron with a highly charged ion

Klasnikov, A. E.; Shabaev, V. M.; Artemyev, A. N.; Kovtun, A. V.; Stöhlker, Th.

doi:10.1016/j.nimb.2005.03.191

“…At the GSI storage ring in Darmstadt, for example, a large number of experiments have been done for the electron capture into bare high-Z ions, giving rise to hydrogen-like ions after the recombination has taken place [1][2][3][4]. In the earlier experiments, the total and angle-differential cross sections have been measured hereby mainly for the ground-state capture and were found in good agreement with computations based on Dirac's equation [5][6][7][8][9][10][11][12][13]. Apart from the RR into the 1s 1/2 ground state, most recent studies have dealt also with the electron capture into the excited ionic states which later decay under the emission of one (or several) characteristic photons [14][15][16].…”

Section: Introductionmentioning

confidence: 56%

“…Making use of the expansion (11) and the Wigner-Eckart theorem, we can now represent the bound-bound transition amplitude…”

Section: Evaluation Of the Free-bound And Bound-bound Transition Ampl...mentioning

confidence: 99%

“…In order to perform such a separation we have to employ the standard (two-component) representation of Dirac's wavefunction and to decompose the electron-photon interaction operator (2) into its partial fields. Most naturally, this decomposition can be carried out if we re-write the polarization vector of the photon in terms of two (linearly independent) basis vectors λ , with λ = ±1 being the photon helicity (i.e., the spin projection on the direction of propagation), and if we make use of the standard expansion [25]: Making use of the expansion (11) and the Wigner-Eckart theorem, we can now represent the bound-bound transition amplitude…”

Section: Evaluation Of the Free-bound And Bound-bound Transition Ampl...mentioning

confidence: 99%

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Polarization studies on the two-step radiative recombination of highly charged, heavy ions

Майорова¹,

Surzhykov²,

Tashenov³

et al. 2009

J. Phys. B: At. Mol. Opt. Phys.

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The radiative recombination of a free electron into an excited state of a bare, high-Z ion is studied, together with its subsequent decay, within the framework of the density matrix theory and Dirac's relativistic equation. Special attention is paid to the polarization and angular correlations between the recombination and the decay photons. In order to perform a systematic analysis of these correlations the general expression for the double-differential recombination cross section is obtained by making use of the resonance approximation. Based on this expression, detailed computations for the linear polarization of x-ray photons emitted in the (e, 2γ) twostep recombination of uranium ions U 92+ are carried out for a wide range of projectile energies.Polarization studies on the two-step radiative recombination

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“…[2,3]). In the recent years several experiments on researching the RR with polarized ion beams were proposed [4,5]. Furthermore, it was proposed to use the RR into polarized H-like ions as the tool for beam spin diagnostic [6].…”

mentioning

confidence: 99%

Production and diagnostics of spin-polarized heavy ions in sequential two-electron radiative recombination

Майорова

¹

,

Surzhykov

²

,

Tashenov

³

et al. 2012

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Within the last decades the radiative recombination (RR) by highly charged heavy ions remains the subject of intense theoretical and experimental research (see [1] and references therein). The RR is an effective tool for studying of the photoionization in the relativistic regime, which is not approachable directly at the present time. Moreover, the RR is interesting due to its sensitivity to the spin, relativistic and QED effects in the structure and dynamics of heavy atomic systems (see, e.g. [2,3]).In the recent years several experiments on researching the RR with polarized ion beams were proposed [4,5]. Furthermore, it was proposed to use the RR into polarized H-like ions as the tool for beam spin diagnostic [6]. Information about the ion polarization is required for studying, for example, the parity nonconservation effects in highly charged ions or in heavy-ion collisions. But all of proposed experiments are hampered now by the lack of polarized ions.In the present work we propose the method, that can be used for investigations of the RR into spin-polarized H-like ions. This approach is based on a subsequent capture of two electrons from two spatially separated targets by initial bare (finally He-like) ion and measurements of two emitted photons in coincidence. We choose the quantization axis (Z-axis) along the momentum p i of the incoming electron. After the capture of the first electron, a photon is emitted in the direction k 1 , determined by polar angle θ 1 . It turns out that the relative magnetic sublevel population of the resulting H-like ion depends on θ 1 . Hence the properties of the second photon, emitted in the direction k 2 characterized by two angles (θ 2 , ϕ 2 ), should be also dependent on θ 1 . The population of the intermediate H-like ion can be parameterized in terms of the polarization vector P = (P x , P y , P z ). From the symmetry considerations in our case, when the photons, emitted in course of recombination of unpolarized electrons with bare ions, are observed in a particular setup, only single parameter P y is non-zero [7].Information about the polarization of the H-like ions can be obtained from the analysis of the linear polarization of the second recombination photons. From the practical viewpoint it is more convenient to use the polarization ellipse parameters P L (the degree of linear polarization) and χ 0 (the orientation of the principal axis with respect to the reaction plane) for the description of the x-ray linear polarization. * Work supported by DFG, Helmholtz association, RFBR, FAIRRussia Research Center, Emmy Noether Programm and GSI.† maiorova@pcqnt1.phys.spbu.ruIn Fig. 1, we display P y as a function of θ 1 and χ 0 as a function of θ 2 in the case of ϕ 2 = 90 o . The calculations have been performed in the ion-rest frame for the incident electron energies ε i =109.7 keV, which correspond to the projectile energy T p = 200 MeV/u in the laboratory frame. As one can see from the figure, the polarization of the Hlike ions following RR is very sensitive to the geometry o...

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Production and diagnostics of spin-polarized heavy ions in the sequential two-electron radiative recombination

Майорова¹,

Surzhykov²,

Tashenov³

et al. 2013

Phys. Scr.

0

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Within the last decades the radiative recombination (RR) by highly charged heavy ions remains the subject of intense theoretical and experimental research (see [1] and references therein). The RR is an effective tool for studying of the photoionization in the relativistic regime, which is not approachable directly at the present time. Moreover, the RR is interesting due to its sensitivity to the spin, relativistic and QED effects in the structure and dynamics of heavy atomic systems (see, e.g. [2,3]).In the recent years several experiments on researching the RR with polarized ion beams were proposed [4,5]. Furthermore, it was proposed to use the RR into polarized H-like ions as the tool for beam spin diagnostic [6]. Information about the ion polarization is required for studying, for example, the parity nonconservation effects in highly charged ions or in heavy-ion collisions. But all of proposed experiments are hampered now by the lack of polarized ions.In the present work we propose the method, that can be used for investigations of the RR into spin-polarized H-like ions. This approach is based on a subsequent capture of two electrons from two spatially separated targets by initial bare (finally He-like) ion and measurements of two emitted photons in coincidence. We choose the quantization axis (Z-axis) along the momentum p i of the incoming electron. After the capture of the first electron, a photon is emitted in the direction k 1 , determined by polar angle θ 1 . It turns out that the relative magnetic sublevel population of the resulting H-like ion depends on θ 1 . Hence the properties of the second photon, emitted in the direction k 2 characterized by two angles (θ 2 , ϕ 2 ), should be also dependent on θ 1 . The population of the intermediate H-like ion can be parameterized in terms of the polarization vector P = (P x , P y , P z ). From the symmetry considerations in our case, when the photons, emitted in course of recombination of unpolarized electrons with bare ions, are observed in a particular setup, only single parameter P y is non-zero [7].Information about the polarization of the H-like ions can be obtained from the analysis of the linear polarization of the second recombination photons. From the practical viewpoint it is more convenient to use the polarization ellipse parameters P L (the degree of linear polarization) and χ 0 (the orientation of the principal axis with respect to the reaction plane) for the description of the x-ray linear polarization. * Work supported by DFG, Helmholtz association, RFBR, FAIRRussia Research Center, Emmy Noether Programm and GSI.† maiorova@pcqnt1.phys.spbu.ruIn Fig. 1, we display P y as a function of θ 1 and χ 0 as a function of θ 2 in the case of ϕ 2 = 90 o . The calculations have been performed in the ion-rest frame for the incident electron energies ε i =109.7 keV, which correspond to the projectile energy T p = 200 MeV/u in the laboratory frame. As one can see from the figure, the polarization of the Hlike ions following RR is very sensitive to the geometry o...

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Polarization effects in radiative recombination of an electron with a highly charged ion

Cited by 4 publications

References 9 publications

Polarization studies on the two-step radiative recombination of highly charged, heavy ions

Polarization studies on the two-step radiative recombination of highly charged, heavy ions

Production and diagnostics of spin-polarized heavy ions in sequential two-electron radiative recombination

Production and diagnostics of spin-polarized heavy ions in the sequential two-electron radiative recombination

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