Monte Carlo simulation of the positron implantation profiles in the layered samples

Theoretical studies of the positron implantation profiles in the layered samples are presented. Simulations performed using a GEANT4 tool kit revealed accumulation of positrons in denser layer embedded by less dens environment. This effect is significant for implantation profiles of slow positrons formed in a beam. Nevertheless, it is also present in conventional experiments, where positrons are emitted from radioactive nuclei. In some cases the diffusion process, which follows the implantation and thermalization processes, can smear this effect. However, defects on the interfaces or differences in the positron affinity can sustain it. (authors)