Radiative electron capture by oxygen ions in single-crystal channels: Experiment and theory

Appleton, B. R.; Ritchie, R.H.; Biggerstaff, J.A.; Noggle, T. S.; Datz, S.; Moak, C. D.; Verbeek, H.; Neelavathi, V. N.

doi:10.1103/physrevb.19.4347

Cited by 38 publications

(15 citation statements)

References 36 publications

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“…This can be seen from a comparison of measured REC cross sections 22 and capture probabilities at relatively large impact parameters compared with nCTMC simulations. 9 It may be shown from simple considerations of the energy-momentum balance, and has been confirmed by experiments 23 that mainly inner-shell electrons are captured at very high ion velocity and that this capture can only take place in a collision with a target atom at a very small impact parameter.…”

Section: B Charge-exchange Modelmentioning

confidence: 95%

Transverse cooling and heating in ion channeling

et al. 2003

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In contrast to predictions from the standard theory of ion channeling we have observed strong redistributions of initially isotropic ion beams after transmission of thin crystal foils. Depending on the experimental parameters, there can be strong enhancements, corresponding to ''transverse cooling,'' or strong reductions, ''transverse heating,'' of the ion flux along a crystal axis or plane. For most ions there is a transition from cooling to heating when the ion energy is decreased, which depends on the crystal direction and on the atomic numbers of the ion and of the crystal atoms. In this paper we present an overview of this newly discovered phenomenon. Redistribution of an initially isotropic flux violates basic symmetries in the theory of channeling. We have argued earlier that the observed transverse cooling or heating can be understood as a consequence of fluctuations in the charge state of the channeled ions, but a detailed explanation of the transition from cooling to heating has yet to be established. A theoretical description is the most difficult for ions with many electrons. A different type of simulation has been developed based on n-body classical trajectory Monte-Carlo procedures and the first results are discussed.

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Section: B Charge-exchange Modelmentioning

confidence: 95%

Transverse cooling and heating in ion channeling

et al. 2003

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“…While the latter is generally easier using gas targets, the situation is much more complex in solid targets. Ion channeling provides a powerful technique to circumvent these problems as has been amply demonstrated in recent atomic-collision experiments [1][2][3][4][5][6]. When heavy ions are channeled along a crystallographic direction the yields of the low-impact-parameter processes such as inner-shell ionization and excitation, Rutherford scattering, etc.…”

Section: Introductionmentioning

confidence: 99%

Radiative electron capture by fully stripped channeled light ions

et al. 1994

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The cross sections for radiative electron capture (REC) into the K shell of bare and H-like light ions of C, 0, F, and S are measured at different energies, under channeling conditions using a Si single crystal as target. These cross section data using different projectiles are shown to fall on a universal curve when plotted against a scaled variable, the adiabaticity parameter q~, of the collision systems. We have observed a definite difference in the cross section between the present solid target data and the available data for a gas target at the same g~v alue. This difference, along with the observed shift in the REC photopeak energy, suggests an "ionsolid-state" effect. Further, these observations, especially their Z dependence, are consistent with the predictions of the theory. PACS number(s): 34.70.+e, 34.50.s, 61.80.Mk

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“…Both results are due to the fact that REC is the only capture process available for channeled particles, as nonradiative capture, which is by far dominant 2 for nonchanneled Xe ions of the energy used here, is excluded like any other low-impact-parameter process. This type of experiment has been undertaken by Appleton et al, 3 who have obtained information on A^-REC cross sections and have shown that the line shape could be explained by the velocity distribution of target electrons, as suggested by Schnopper et al 4 who first observed REC. The swift heavy ions used in our experiment have great advantages; K, L and M REC can be studied precisely, and the cross sections have been measured and compared with theoretical predictions.…”

Section: Observation Of Radiative Electron Capture Into K L M Shellmentioning

confidence: 96%

“…Andriamonje, (1) M. Chevallier, (2) C. Cohen, (3) J. Dural, (4) M. J. Gaillard, (2) R. Genre, (2) M. HageAli, (5) R. Kirsch, (2) A. L'Hoir, (3) B. Mazuy, (2) J. Mory, (6) J. Moulin, (3) J. C. Poizat, (2) J. Remillieux, (2) D. Schmaus, (3) and M. Toulemonde (4) We report on the new features observed in the study of the charge-exchange process of fast H-like xenon ions channeled in a thin silicon crystal. The simultaneous study of the charge state of the transmitted Xe ions and of the x rays they radiate has lead to the following results: (i) Channeled particles appear to be essentially "frozen" in their initial 53 + charge state (a feature already observed by Datz et al l with lighter ions), while the mean charge state for nonchanneled particles is 49.5.…”

Section: Observation Of Radiative Electron Capture Into K L M Shellmentioning

confidence: 99%

Observation of radiative electron capture intoK,L,Mshells of 25-MeV/uXe53+ions channeled in silicon

et al. 1987

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We present experimental results showing that channeling measurements with fast stripped heavy ions incident on thin crystals can allow a detailed study of radiative electron capture. Charge-state measurements and photon-energy spectra have been used to deduce cross sections of radiative capture into the K, L, and M shells of 25-MeV/u Xe 53+ ions. The orientation dependence of the positions and shapes of associated photon lines has been observed. PACS numbers: 34.70.+e, 34.50.-s, 61.80.MkWe report on the new features observed in the study of the charge-exchange process of fast H-like xenon ions channeled in a thin silicon crystal. The simultaneous study of the charge state of the transmitted Xe ions and of the x rays they radiate has lead to the following results: (i) Channeled particles appear to be essentially "frozen" in their initial 53 + charge state (a feature already observed by Datz et al. l with lighter ions), while the mean charge state for nonchanneled particles is 49.5. (ii) In the x-ray spectrum, strong, or at least well resolved, lines show up that are due to radiative electron capture (REC) into the K, L, and M shells of channeled projectiles. Both results are due to the fact that REC is the only capture process available for channeled particles, as nonradiative capture, which is by far dominant 2 for nonchanneled Xe ions of the energy used here, is excluded like any other low-impact-parameter process. This type of experiment has been undertaken by Appleton et al.,3 who have obtained information on A^-REC cross sections and have shown that the line shape could be explained by the velocity distribution of target electrons, as suggested by Schnopper et al. 4 who first observed REC. The swift heavy ions used in our experiment have great advantages; K, L and M REC can be studied precisely, and the cross sections have been measured and compared with theoretical predictions. The line shapes appear very clearly and can be analyzed in great detail. This will be done in a forthcoming paper. Moreover the joint study of charge states and REC intensity shows that electron capture by channeled particles is completely accounted for by REC.We used 25-MeV/u Xe 53+ ions delivered at Grand Accelerateur National dTons Lourds (GANIL) in the LISE beam line, which provided a beam of angular divergence lower than 0.5 mrad. Before reaching the crystal, the beam passes through a rotating chopper used for beam monitoring. The chopper blades are covered with silver and the Ag x-ray yield is measured by a Si-Li x-ray detector. The crystal, a 17-pm-thick (ill) Si crystal of area about 1 cm 2 , is viewed by a solid-state Ge detector positioned at 90° to the beam. The transmitted ions are charge and energy analyzed by a magnetic spectrometer associated with a wire chamber (the angular acceptance allows the detection of all the particles). The experiment has been performed around the (110) axial direction. The charge-state measurements are performed as follows: The electric charges collected on each wire are integrated over an ad...

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Radiative electron capture by oxygen ions in single-crystal channels: Experiment and theory

Cited by 38 publications

References 36 publications

Transverse cooling and heating in ion channeling

Transverse cooling and heating in ion channeling

Radiative electron capture by fully stripped channeled light ions

Observation of radiative electron capture intoK,L,Mshells of 25-MeV/uXe53+ions channeled in silicon

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