Ionization and positron emission in giant quasiatoms

Electron excitation processes in superheavy quasiatoms are treated within a relativistic framework. Theoretical results on K‐hole production rates as well as δ‐electron and positron spectra are compared with experimental data. It is demonstrated that the study of heavy ion collisions with nuclear time delay promises a signature for the spontaneous positron formation in overcritical systems. Corresponding experimental results are confronted with our theoretical hypothesis. Recent speculations on the origin of the observed peak structures in positron spectra are critically reviewed. Atomic excitations are also employed to obtain information on the course of a nuclear reaction. Using a semiclassical picture we calculate the emission of δ‐electrons and positrons in deep‐inelastic nuclear reactions. Furthermore some consequences of conversion processes in giant systems are investigated.