The Consequences of Sudden Rearrangements of Electronic Shells

Abstract

We investigate the influence of sudden rearrangement processes in the electron distribution of the two-centre potential on electron and positron spectra emitted in heavy ion collisions. Using a schematic ansatz for the matrix elements, a scaling law is deduced, which predicts oscillations in the emission spectra. Coincident electronpositron emission in the system Pb + Pb at E _Lab = 5.7 MeV/n was evaluated using a full coupled channel code under the assumption that the rearrangement effects may be simulated by adding a Gaussian to the matrix elements at position R ₈ . Pronounced structures are found for certain cuts in the plane spanned by the kinetic electron and positron energies. Surprisingly, electron and positron production cross sections peak at the same energies. Hence there is great resemblance of this phenomenon with experimental observations on e ⁺-e ^- spectra in heavy ion collisions.