[en] Experiments have been performed at GSI HI-accelerator to investigate positron creation induced in the collision between very heavy atoms. In particular, the investigations are focussing on the isolation of the processes leading to direct positron production in the Coulomb fields of the colliding systems, and induced and spontaneous emission in overcritical electric fields. Both total cross sections and differential cross sections with respect to the scattered ions are being explored, utilizing two instruments possessing somewhat complementary features of positron detection and background suppression. (orig.)