| 1. |
- Gumberidze, A., et al.
(författare)
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Electron- and proton-impact excitation of heliumlike uranium in relativistic collisions
- 2019
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 99:3
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the K-shell excitation of He-like uranium (U90+) in relativistic collisions with hydrogen and argon atoms. Performing measurements with different targets, as well as with different collision energies, enabled us to explore the proton- (nucleus-) impact excitation as well as the electron-impact excitation process for the heaviest He-like ion. The large fine-structure splitting in uranium allowed us to partially resolve excitation into different L-shell levels. State-of-the-art relativistic calculations which include excitation mechanisms due to the interaction with both protons (nucleus) and electrons are in good agreement with the experimental findings. Moreover, our experimental data clearly demonstrate the importance of including the generalized Breit interaction in the treatment of the electron-impact excitation process.
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| 2. |
- Misra, Deepankar, et al.
(författare)
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Two-Center Double-Capture Interference in Fast He2++H2 Collisions
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:15, s. 153201-
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Tidskriftsartikel (refereegranskat)abstract
- We report the first observation of Young-type interference effects in a two-electron transfer process. These effects change strongly as the projectile velocity changes in fast (1.2 and 2.0 MeV) He^{2+}-H_2 collisions as manifested in strong variations of the double-electron capture rates with the H_2 orientation. This is consistent with fully quantum mechanical calculations, which ignore sequential electron transfer, and a simple projectile de Broglie wave picture assuming that two-electron transfer probabilities are higher in collisions where the projectile passes close to either one of the H_2 nuclei.
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| 3. |
- Schulz, M., et al.
(författare)
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Strongly Enhanced Backward Emission of Electrons in Transfer and Ionization
- 2012
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:4, s. 043202-
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Tidskriftsartikel (refereegranskat)abstract
- We studied three-dimensional angular distributions and longitudinal momentum spectra of electrons ejected in transfer plus ionization (TI), i.e., the ejection of one and the capture of a second target electron, for ion-helium collisions. We observe a pronounced structure strongly focused opposite to the projectile beam direction, which we associate with a new correlated TI mechanism proposed recently. This process contributes significantly to the total cross sections over a broad range of perturbations eta, even at eta as large as 0.5, where uncorrelated TI mechanisms were thought to be dominant.
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| 4. |
- Wang, X., et al.
(författare)
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Mutual projectile and target ionization in 1-MeV/amu N(4+) and N(5+) + He collisions
- 2011
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 84:2, s. 022707-
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Tidskriftsartikel (refereegranskat)abstract
- We have studied mutual projectile and target ionization in 1-MeV/amu N(4+) and N(5+) + He collisions in kinematically complete experiments by measuring the momenta of the recoil ion and both ejected electrons in coincidence with the charge-changed projectiles. By means of four-particle Dalitz plots, in which multiple differential cross sections are presented as a function of the momenta of all four particles, experimental spectra are compared with theoretical results from various models. The experimental data are qualitatively reproduced by higher-order calculations, where good agreement is achieved for N(5+) + He collisions, while some discrepancies persist for N(4+) + He collisions.
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