Target ionization and projectile charge changing in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>0.5</mml:mn><mml:mo>–</mml:mo><mml:mn>8</mml:mn><mml:mo>−</mml:mo><mml:mi mathvariant="normal">MeV</mml:mi><mml:mo>/</mml:mo><mml:mi>q</mml:mi><mml:mi> </mml:mi><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Li</mml:mi></mml:mrow><mml:mrow><mml:mi>q</mml:mi><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow><mml:mo>+</mml:mo><mml:mi mathvariant="normal">He</mml:mi

Woitke, O.; Závodszky, Péter; Ferguson, S. M.; Houck, J.; Tanis, J. A.

doi:10.1103/physreva.57.2692

Cited by 68 publications

(72 citation statements)

References 15 publications

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“…Transfer ionization, where one electron is captured into a bound state of the projectile and a second one is released into the continuum, have been studied in great detail [2][3][4][5][6][7][8][9][10][11][12][13][14] and have led to a better understanding of initial and final state correlation [15][16][17]. Instead of being lifted to the continuum, the second target electron can also be promoted to a bound but excited state.…”

Section: Introductionmentioning

confidence: 99%

Transfer excitation reactions in fast proton-helium collisions

et al. 2014

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Continuing previous work, we have measured the projectile scattering-angle dependency for transfer excitation of fast protons (300-1200 keV/u) colliding with helium (p+He → H + He + * ).Our high-resolution fully differential data are accompanied by calculations, performed in the planewave first Born approximation and the eikonal wave Born approximation. Experimentally, we find a deep minimum in the differential cross section around 0.5 mrad. The comparison with our calculations shows that describing the scattering-angle dependence of transfer excitation in fast collisions requires us to go beyond the first Born approximation and in addition to use the initial state-wave function, which contains some degree of angular correlations. * Electronic address: schoeffler@atom.uni-frankfurt.de

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Section: Introductionmentioning

confidence: 99%

Transfer excitation reactions in fast proton-helium collisions

et al. 2014

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“…The comparison of the calculated cross sections with the experimental data of Woitke et al [36] for the four-electron system Li + + He is shown in figure 3. Here, the solid triangles and the dotted line are the results for the single-loss -single-ionization process, the solid circles and the dashed line correspond to the single-loss -double-ionization process, and the solid squares and the solid line are the results for the total electron loss cross sections.…”

Section: Calculations Of the Probabilities And Cross Sectionsmentioning

confidence: 99%

“…For the electron loss of Li 2+ by He, the comparison with the experimental data of Woitke et al [36] is shown in figure 2. In this figure, the triangles and the dotted line are the results for the single-loss -single-ionization process, while the circles and the dashed line are those for the single-lossdouble-ionization process.…”

Section: Calculations Of the Probabilities And Cross Sectionsmentioning

confidence: 99%

“…In section 2, the main features of the IEVM are introduced and the recipes to obtain the total transition probabilities are fully presented. In section 3, the calculations are compared with the cross sections of total single-electron loss and electron loss accompanied by single and double ionization of the target of Li + and Li 2+ ions by He atoms [36,37], and of He + ions also by He atoms [38,39,40]. The specific contributions of the antiscreening mechanism to the total cross sections are analyzed in section 4.…”

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confidence: 99%

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Two-center electron-electron correlation within the independent event model

Sigaud¹,

Montenegro²

2003

Braz. J. Phys.

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The Independent Event Model (IEVM) is used to analyze collision processes for systems with three and four electrons, in situations where up to three active electrons are involved and dynamical correlation effects play a major role. The model is applied to single electron loss and loss-ionization processes. All the possible ionization mechanisms for both collision partners in each exit channel are considered, including antiscreening, which, in the IEVM, can be taken into account in a consistent way along all the other ones, keeping unitarity. As a casestudy, the IEVM is applied to the analysis of the single loss of He + , Li + , and Li 2+ ions by He atoms with the simultaneous single and double ionization of the target. We present plots of the cross sections of single electron loss accompanied or not by the ionization of the target as functions of the projectile energy. The calculations describe well the experimental energy dependence and the high-velocity absolute values for the cross sections. I IntroductionCollisions between dressed ions -considered here as ions which carry electrons -and neutral atoms, when both collision partners have active electrons, present a multiplicity of possible simultaneous exit channels which result in singleor multi-electron transitions within and between the participating systems. Some of these channels include the single or multiple ionization of the projectile and of the target atom, followed -or not -by the capture of one -or more -target electrons by the incoming ion. Particular attention, from both the experimental and theoretical points of view, has been drawn in recent years to the simultaneous ionization of dressed projectiles colliding with neutral noble gas targets, which is governed by two competing mechanisms, the so-called direct loss-ionization and antiscreening modes [1,2,3,4]. The importance of the dynamical electron correlation in this type of collision is now well established, in particular at intermediate and high velocities, where the electron-electron interaction (antiscreening) can dominate the total electron loss cross section [5,6]. This has been evinced experimentally by the measurement either of total cross sections [7,8,9] or of the momentum distributions of the recoil ions, which provide a definite signature for the antiscreening mechanism [10,11,12,13].The simultaneous occurrence of competing processes, mainly when they include two-center electron correlation, renders difficult a comprehensive theoretical description of the collision. Only in the simplest cases, single-channel analyses can be used to describe properly the experimental results. The pioneering works of Bates and Griffing [14] provided the first description of such electron-loss processes within the first-Born approximation. Actually, the behavior of both the screening and the antiscreening modes for light targets is conveniently described by first-order models, such as the plane wave Born approximation (PWBA) [2,3,15,16,17].There are not many options available to treat collision syste...

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“…Iodine isotopes 108,127,144 I for heavier isotopes and 6,9,11 Li for the very lighter mass region. The choice of these nuclides was also based on the availability of data for low-energy charge-exchange cross sections with helium [14,15].…”

Section: Beam Stopping Simulationsmentioning

confidence: 99%

The cyclotron gas stopper project at the NSCL

et al. 2007

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Gas stopping is becoming the method of choice for converting beams of rare isotopes obtained via projectile fragmentation and in-flight separation into low-energy beams. These beams allow ISOL-type experiments, such as mass measurements with traps or laser spectroscopy, to be performed with projectile fragmentation products. Current gas stopper systems for high-energy beams are based on linear gas cells filled with 0.1-1 bar of helium. While already used successfully for experiments, it was found that space charge effects induced by the ionization of the helium atoms during the stopping process pose a limit on the maximum beam rate that can be used. Furthermore, the extraction time of stopped ions from these devices can exceed 100 ms causing substantial decay losses for very short-lived isotopes. To avoid these limitations, a new type of gas stopper is being developed at the NSCL/MSU. The new system is based on a cyclotron-type magnet with a stopping chamber filled with Helium buffer gas at low pressure. RF-guiding techniques are used to extract the ions. The space charge effects are considerably reduced by the large volume and due to a separation between the stopping region and the region of highest ionization. Cyclotron gas stopper systems of different sizes and with different magnetic field strengths and field shapes are presently investigated.

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Target ionization and projectile charge changing in0.5–8−MeV/q Liq++He

Cited by 68 publications

References 15 publications

Transfer excitation reactions in fast proton-helium collisions

Transfer excitation reactions in fast proton-helium collisions

Two-center electron-electron correlation within the independent event model

The cyclotron gas stopper project at the NSCL

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