A Survey of E1 Transitions in the Rare Earth Region

Abstract

Publisher Summary In the rare-earth region of the periodic table, there are several nuclei in which E1 transitions exhibit anomalous conversion coefficients. The enhancement of K-, L I -, and L II -conversion is observed to be as high as ten times the theoretical values. A survey of all predominantly E1 transitions in the rare-earth region was made in order to establish the cause of the observed anomalies. The data on measured conversion coefficients were divided into groups consistent with the penetration-conversion picture. The penetration-matrix-element formalism may be used to distinguish three ways in which the nucleus gives up energy: (1) photon emission, (2) normal internal conversion, and (3) penetration-conversion, in which the electron is present inside the nucleus. The chapter also illustrates the three interactions that affect the penetration-conversion: (1) the nuclear charge, (2) the intranuclear currents, and (3) the nucleon spin-currents.