Theory of positron production in heavy-ion collisions

Collisions of very heavy ions at energies close to the Coulomb barrier are discussed as a unique tool to study the behavior of the electron-positron field in the presence of strong external electromagnetic fields. To cal
Collisions of very heavy ions at energies close to the Coulomb barrier are discussed as a unique tool to study the behavior of the electron-positron field in the presence of strong external electromagnetic fields. To calculate the excitation processes induced by the collision dynamics, a semiclassical model is employed and adapted to describe the field-theoretical many-particle system. An expansion in the adiabatic molecular basis is chosen. Energies and matrix elements are calculated using the monopole approximation. In a supercritical (Z1+Z2≳173) quasiatomic system the 1s level joins the antiparticle continuum and becomes a resonance, rendering the neutral vacuum state unstable. Several methods of treating the corresponding time-dependent problem are discussed. A projection-operator technique is introduced for a fully dynamical treatment of the resonance. Positron excitation rates in s1/2 and p1/2 states are obtained by numerical solution of the coupled-channel equations and are compared with results from first- plus second-order perturbation theory. Calculations are performed for subcritical and supercritical collisions of Pb-Pb, Pb-U, U-U, and U-Cf. Strong relativistic deformations of the wave functions and the growing contributions from inner-shell bound states lead to a very steep Z dependence of positron production. The results are compared with available data from experiments done at GSI. Correlations between electrons and positrons are briefly discussed.
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Metadaten
Author:Joachim Reinhardt, Berndt Müller, Walter Greiner
URN:urn:nbn:de:hebis:30-29182
Document Type:Article
Language:English
Date of Publication (online):2006/06/30
Year of first Publication:1981
Publishing Institution:Univ.-Bibliothek Frankfurt am Main
Release Date:2006/06/30
Source:Phys. Rev. A 24, 103~V128 (1981), ©1981 The American Physical Society, http://link.aps.org/abstract/PRA/v24/p103
HeBIS PPN:187225885
Institutes:Physik
Dewey Decimal Classification:530 Physik
Sammlungen:Universitätspublikationen
Licence (German):License Logo Veröffentlichungsvertrag für Publikationen

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