Theory of positron production in heavy-ion collisions

摘要: Collisions of very heavy ions at energies close to the Coulomb barrier are discussed as a unique tool study behavior electron-positron field in presence strong extemal electromagnetic fields. To calculate excitation processes induced by collision dynamics, semiclassical model is employed and adapted describe field-theoretical many-particle system. An expansion adiabatic molecular basis chosen. Energies matrix elements calculated using monopole approximation. In supercritical (2, + Z, 2 173) quasiatomic system 1s level joins antiparticle continuum becomes resonance, rendering neutral vacuum state unstable. Several methods treating corresponding time-dependent problem discussed. A projectionOperator technique introduced for fully dynamical treatment resonance. Positron rates s„, andp,,] states obtained numencal solution coupled-channel equations compared with results from first- plus second-order perturbation theory. Calculations performed subcritical collisions Pb-Pb, Pb-U, U-U, U-Cf. Strong relativistic deformations wave functions growing contributions inner-shell bound lead steep Z dependence positron production. The available data experiments done GSI. Correlations between electrons positrons briefly