Coupled-channel calculations of K-shell ionisation in asymmetric collision systems

Mehler, Gerlinde; Greiner, Walter; Soff, G.

doi:10.1088/0022-3700/20/12/023

Cited by 14 publications

(9 citation statements)

References 34 publications

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“…The binding effect vanishes because of the high projectile velocity. Flowback of occupation probability from the continuum states reduces ionization at projectile charges of about Ze > 7 [17,18]. Thus, the inclusion of the above mentioned matrix elements only served testing purposes and, indeed, yielded negligible results.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…The upper electron continuum with E~> I is discretized by means of relativistic wave-packets [16,17]. Thus the index i in the sum of (6) takes on only discrete values.…”

Section: L~r =~ P + F L -E Vr(r)mentioning

confidence: 99%

“…Such subtle trajectory effects are at the moment beyond the scope of theoretical and experimental analysis, as far as their influence on electronic excitation rates is concerned and may therefore be neglected. This paper is based on earlier work of the authors [16][17][18]. We will therefore not discuss features of the formalism, which have been published previously, but concentrate on the modifications due to the relativistic projectile motion.…”

Section: Introductionmentioning

confidence: 99%

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K-shell ionization in relativistic ion-atom collisions

Mehler

Soff²,

Rumrich

et al. 1989

Z Phys D - Atoms, Molecules and Clusters

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We present calculations of K-shell ionization probabilities in asymmetric ion-atom collisions at relativistic velocities of the projectile. The time-dependent Dirac equation is represented as a system of coupled differential equations. The transition probabilities are determined using the coordinate space method. This necessitates an extension of the angular momentum coupling compared with nonrelativistic collision systems. Effects of the relativistic projectile motion on the coupling matrix elements and their consequences on K-shell ionization are discussed.

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Section: Numerical Resultsmentioning

confidence: 99%

“…The upper electron continuum with E~> I is discretized by means of relativistic wave-packets [16,17]. Thus the index i in the sum of (6) takes on only discrete values.…”

Section: L~r =~ P + F L -E Vr(r)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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K-shell ionization in relativistic ion-atom collisions

Mehler

Soff²,

Rumrich

et al. 1989

Z Phys D - Atoms, Molecules and Clusters

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“…The last term, Hrad, is the Hamiltonian for electromagnetic radiation; it depends on nuclear and electronic coordinates since it contains coupling terms of the electromagnetic potential to the nuclear and electronic currents. Hrad has to be taken into account for the calculation of x-ray spectra (Kirsch et a1 1978, 1980, b, 1982, nuclear bremsstrahlung (Feshbach and Yennie 1962, Reinhardt et a1 1976, 1987, and internal conversion (Schluter et a1 1978(Schluter et a1 , 1981 of nuclear into electron excitations.…”

Section: The Scattering Problemmentioning

confidence: 99%

Interplay of nuclear and atomic physics in ion-atom collisions

Heinz¹

1987

Rep. Prog. Phys.

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The interplay between atomic and nuclear interactions in collisions between light and heavy ions is studied. The general theoretical description is outlined and analysed in a number of different limits (non-relativistic and relativistic electrons, semiclassical approximation, DWBA, fully quantal description) that have been used in practical applications. The two most important physical mechanisms for generating atomicnuclear interference, i.e. energy conservation and the introduction of additional phase shifts by nuclear reactions, are extracted and their universality in all scattering systems is stressed. The need for choosing different sets of basis states in light and heavy, symmetric and asymmetric systems, in order to achieve an economical theoretical description, is discussed in some detail. The resulting typical coupling matrix elements are analysed for their relative importance in atomic and nuclear excitations. The description of nuclear influence on atomic excitations in terms of a classical time delay caused by nuclear reactions is reviewed and its relationship to the underlying quantal character of the nuclear reaction is extracted.An experimental chapter reviews the existing data on nuclear-atomic interference. A large section covers proton-induced reactions (through isobaric analogue resonances or compound-nucleus formation) and their effects on bremsstrahlung spectra, K-hole probabilities, x-ray emission and electron capture. Inverse processes, where excitations within the electron shell modify the nuclear scattering, are also described. That structures in the atomic spectra can be consistently used to extract nuclear reaction times or average nuclear resonance widths is demonstrated for compound-nucleus formation in light-ion scattering and later applied to heavy-ion reactions. The experimental use of K-hole, 8-electron and positron production in heavy-ion reactions as an atomic clock for nuclear delay times is discussed; it is shown to give consistent results even in a region where direct determination of these times from measurement of nuclear reaction products is so far impossible.A prominent place in this review is reserved for spontaneous positron emission in supercritical heavy-ion collisions (Z,,, B 173); line structures predicted in the positron energy spectra may provide the most sensitive mechanism to isolate even very small fractions of the nuclear cross section proceeding through strongly delayed resonances or reaction channels. Attempts to use this idea to interpret the recently discovered

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“…Ionization in nonperturbative collisions has been studied in many works, some of them quite early. In some studies of Greiner's Group [3], [4] the continuum was taken into account by expansion over a set of real continuum states, while in the papers of Reading's Group (first in ref. [5]), as well as e.g.…”

Section: Introductionmentioning

confidence: 99%

Ionization channel in non-perturbative ion-atom collisions dominated by charge exchange

Kocbach¹,

Ladadwa²

2001

AIP Conference Proceedings

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The development of the described method has been motivated by studies of the proton-atomic oxygen collision system, where the accidental closeness of energy levels makes the charge exchange quasi-resonant. In slow collisions the ionization channel must compete with the resonant exchange channel. The present theoretical approach is to add target continuum states, found by solving numerically the self-consistent field Schrödinger equation, to the set of basis states on target and projectile, as used in close coupling treatment of excitation and exchange. We have shown that the chosen theoretical approach is feasible and report here first model studies using the new computer code. It is found that the large population of the ionization channel at the lowest collision velocities found in a previous study is not seen in the present approach.

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Coupled-channel calculations of K-shell ionisation in asymmetric collision systems

Cited by 14 publications

References 34 publications

K-shell ionization in relativistic ion-atom collisions

K-shell ionization in relativistic ion-atom collisions

Interplay of nuclear and atomic physics in ion-atom collisions

Ionization channel in non-perturbative ion-atom collisions dominated by charge exchange

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