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 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.
Author: | Joachim ReinhardtGND, Berndt MüllerORCiDGND, Walter GreinerGND |
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URN: | urn:nbn:de:hebis:30-29182 |
URL: | http://link.aps.org/abstract/PRA/v24/p103 |
Parent Title (German): | Physical review A |
Document Type: | Article |
Language: | English |
Date of Publication (online): | 2006/06/30 |
Year of first Publication: | 1981 |
Publishing Institution: | Universitätsbibliothek Johann Christian Senckenberg |
Release Date: | 2006/06/30 |
Volume: | 24 |
Issue: | 1 |
Page Number: | 26 |
First Page: | 103 |
Last Page: | 128 |
HeBIS-PPN: | 187225885 |
Institutes: | Physik / Physik |
Dewey Decimal Classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
Licence (German): | Deutsches Urheberrecht |