Influence of Retardation on the Angular Distribution of Radiative Electron Capture

Spindler, E.; Betz, Hans Dieter; Bell, F.

doi:10.1103/physrevlett.42.832

Cited by 63 publications

(28 citation statements)

References 9 publications

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“…The data corrected for Doppler effect give the REC energies in the projectile frame. A linear dependence of these centroid energies on the projectile energy is found in accordance with previous observations [5]. The centroid energy, ERic, is given by:…”

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confidence: 56%

“…Additionally, in the case of bound target electrons, transverse momenta occur which give rise to small intensity enhancements, especially at small forward and backward angles [5]. The extracted intensities of REC lines, i.e.…”

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confidence: 99%

“…REC of free electrons, considered as a time reversed photoeffect, has been known for a long time [1]. However, it was not until 1972 that REC of bound, quasi-free target electrons was observed [2] and studied intensively, both experimentally and theoretically [3][4][5][6][7][8][9][10][11][12][13][14][15]. Within the impulse approximation quasi-free electrons can be treated as free as long as the binding energy in the target atom can be neglected with respect to the kinetic electron energy seen in the projectile frame.…”

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confidence: 99%

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Radiative electron capture into theK-, L- andM-Shell of decelerated, hydrogenic Ge projectiles

Stöhlker

Kozhuharov

Livingston

et al. 1992

Z Phys D - Atoms, Molecules and Clusters

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Abstract. Radiative Electron Capture (REC) in 4 to 12MeV/u Ge31+---~H2 collisions has been studied using an X-ray/particle coincidence technique. This technique allowed a systematic investigation of K-shell REC as well as a separation of REC into the projectile L-and Mshells. The cross sections are discussed within a general scaling picture based on the reduced projecti!e velocity. PACS: 34.70. + e When a highly charged ion interacts with a neutral target atom several recombination processes are possible. Radiative Electron Capture (REC) is a recombination phenomenon in which the highly charged ion captures a target electron and emits a photon. REC of free electrons, considered as a time reversed photoeffect, has been known for a long time [1]. However, it was not until 1972 that REC of bound, quasi-free target electrons was observed [2] and studied intensively, both experimentally and theoretically [3][4][5][6][7][8][9][10][11][12][13][14][15]. Within the impulse approximation quasi-free electrons can be treated as free as long as the binding energy in the target atom can be neglected with respect to the kinetic electron energy seen in the projectile frame. Detailed knowledge of the REC process is important for an understanding of ionic states in solid matter [12,16,17], tbr a description of capture processes in high energy collisions [15"], for modelling of electron cooling processes in storage rings [18], and the estimations of lifetimes of highly charged stored ions. Very recently, the application of REC for structure studies of heavy few-electron ions has been proposed as well [19].In this letter we report on the first systematic case studies for K-, L-, and M-REC observed in collisions of highly charged, decelerated heavy ions (Ge 31 +) with a H2 gas target in the energy range 4.5 to 11.5 MeV/u. It should be noted that the simultaneous detection of all three processes in one collision system is very difficult * Supported by KBN, Poland; Grant No. 201779101 due to background in the X-ray spectra produced by inner-shell excitation or ionization, non-radiative electron capture into projectile excited states, and electron bremsstrahlung. Therefore, in order to reduce the background from competing processes, coincidences between X-Rays and projectiles which captured one electron were registered in our experiment. To date, simultaneous observation of K-, L-, and M-REC was only possible for channeling conditions at energies similar to those used in our experiment [12]. In this case small impact-parameter processes like K-shell excitation and non-radiative capture were strongly reduced.The hydrogenic Ge 3t+ projectiles, at the energies mentioned above, were produced at the UNILAC facility of GSI Darmstadt by stripping in a C foil at 11.5 MeV/u and by subsequent deceleration down to the appropriate energies [20]. The charge state analyzed beam was collimated and directed into the collision area which consisted of an open, triply differentially pumped gas target. The central part of the target of 7.5 mm length was ob...

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confidence: 56%

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confidence: 99%

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confidence: 99%

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Radiative electron capture into theK-, L- andM-Shell of decelerated, hydrogenic Ge projectiles

Stöhlker

Kozhuharov

Livingston

et al. 1992

Z Phys D - Atoms, Molecules and Clusters

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“…The sharp increase in the anisotropy at low x-ray energies is due to the onset of the radiative-electron capture (REC) tail of C1 [24]. Since the REC radiation intensity varies as sin 20, the rise would be present even if the correct Doppler correction for REC (v=0) were applied [25].…”

Section: I(30 ~ E X)mentioning

confidence: 99%

Molecular-orbital X-rays and their anisotropies in heavy-ion collisions in solids and gases

1981

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Molecular-orbital spectra and anisotropies were measured in CI+NaC1, CI+KC1, C1 +Ti, and CI+Ar collisions at bombarding energies between 0.5 and 2.6MeV/a.m.u. The results suggest that at low bombarding energies MO x-rays in the KC1 and NaCI targets are partly produced by a two-collision process. Qualitative differences between the anisotropies of gas-and solid-target induced MO x-ray spectra underline this result. Also, new information on the bombarding-energy dependency of anisotropies at higher projectile velocities has been obtained, confirming previous observations in low-Z systems.

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“…Figure 2 shows the measured spectra. The REC photons are strongly anisotropic [14,15]. In order to correct for this effect the coincidence yields were analysed according to the formula:…”

Section: Coincidence Experimentsmentioning

confidence: 99%

Radiative and non-radiative electron capture from carbon atoms by relativistic helium ions

Gójska¹,

Chmielewska²,

Rymuza³

et al.

The 2nd International Conference on Nuclear Physics in Astrophysics

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Abstract. Interaction of radiation with helium atoms and/or ions is of interest in various astrophysical applications. The reverse reactions of fast 150 MeV/amu 3 He ++ ions with solid C targets have been studied at the isochronous cyclotron of the RCNP in Osaka. The singly ionized helium ions resulting from capture of the target electrons to the projectile were observed with the use of large magnetic spectrograph, Grand Raiden, set at θ = 0• with respect to the beam. The yield ratios of singly-to-doubly ionized helium ions emerging from thin carbon foils, He + /He ++ , have been measured as a function of the foil thickness. Extrapolating the results to zero target thickness permits to determine the cross section values separately for electron stripping from 3 He + ions and for electron capture to 3 He ++ ions. The radiative and nonradiative contributions to the capture cross section were determined in a separate experiment in which the 84 keV (C.M.) photons were observed in coincidence with the He + ejectiles. The results are compared with theoretical predictions. Need for improved calculations is noted for all the three processes involved, i.e. for the radiative and non radiative electron capture as well as for the electron stripping.PACS. 25.40.Lw Radiative capture -34.70.+e Charge transfer

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Influence of Retardation on the Angular Distribution of Radiative Electron Capture

Cited by 63 publications

References 9 publications

Radiative electron capture into theK-, L- andM-Shell of decelerated, hydrogenic Ge projectiles

Radiative electron capture into theK-, L- andM-Shell of decelerated, hydrogenic Ge projectiles

Molecular-orbital X-rays and their anisotropies in heavy-ion collisions in solids and gases

Radiative and non-radiative electron capture from carbon atoms by relativistic helium ions

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