Positron-electron angular correlations in internal pair conversion

Abstract

The internal pair conversion (IPC) of transitions in Pb nuclei has been studied. Recent calculations of IPC for transitions with energies up to 2 MeV predict large differences in the shapes of the angular correlations according to their magnetic or electric character. We have measured absolute pair-conversion coefficients for E1 transitions in {sup 206}Pb and an M1 transition in {sup 207}Pb with uncertainties three to five times smaller than previous measurements. The measured positron-electron angular correlations are in good agreement with the predictions of the recent calculations and display the predicted differences between the electric and magnetic cases. {copyright} {ital 1998} {ital The American Physical Society}