Messung der Paarkonversionskoeffizienten von59Co

Internal pair formation propabilities in⁶⁰Ni and⁵⁹Co have been determined by a positron annihilation method. The electrons from the β^?-decay of⁵⁹Fe were measured in triple coincidence with annihilation quanta originating from pairs produced in the deexcitation of the⁵⁹Co nucleus. By this triple coincidence technique it was possible to measure separately the pair formation coefficients Γ for transitions in⁵⁹Co. The observed values Γ_1.29=(3.7±0.4)×10^?5 and Γ_1.10=(0.5±0.1)×10^?5 are in agreement with theoretical calculations forE2-radiation.