Theory of positron production in heavy-ion collisions

Journal Article · Wed Jul 01 04:00:00 EDT 1981 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.24.103· OSTI ID:6194063

Reinhardt, J; Mueller, B; Greiner, W

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 (Z/sub 1/+Z/sub 2/> or approx. =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 s/sub 1/2/ and p/sub 1/2/ 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.

• Research Organization: Institut fuer Theoretische Physik, Johann Wolfgang Goethe Universitaet, 6000 Frankfurt am Main, West Germany
• OSTI ID: 6194063
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 24:1; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
CALIFORNIUM IONS
CHARGED PARTICLES
COLLISIONS
COULOMB FIELD
ELECTRIC FIELDS
ELECTRON PAIRS
ELEMENTARY PARTICLES
FERMIONS
FIELD THEORIES
GENERAL RELATIVITY THEORY
HEAVY IONS
INTERACTIONS
ION COLLISIONS
ION-ION COLLISIONS
IONS
LEAD IONS
LEPTONS
PAIR PRODUCTION
POSITRONS
RELATIVITY THEORY
SEMICLASSICAL APPROXIMATION
URANIUM IONS