Non-existence of dynamic contributions to the 412 keV E2 conversion process in Hg198 demonstrated by a new experimental method

A new experimental technique for the study of the internal conversion process has been developed and applied for an investigation of the 412 keV E2 transition in Hg198. The new method implies an indirect and accurate determination of the particle parameter b2(E2) as well as of the internal conversion coefficient αK(E2). Both quantities are derived from an experimental measurement of the b4(E2) particle parameter. It is shown that the accuracy in the value for b2(E2) thus obtained is considerably higher than would be possible on the basis of a direct measurement of b2(E2). On the basis of the theory of Green and Rose the parameter b2(E2), when accurately determined, may be used to derive experimental values for the dynamic contributions to the radial matrix element R−3and R+2 governing the E2 conversion process. These contributions were found to be negligible within narrow limits of experimental errors. Finally. we calculate αK(E2) using our experimentally determined radial matrix elements. The value for αK(E2) of the 412 keV E2 transition in Hg198 thus obtained becomes αK(present exp)=(308±9) · 10−4, in perfect agreement with the theoretical values obtained by Rose and by Sliv and Band and also with the more recent experimental determinations based on the external-internal conversion method, αK(ext. int. conv.)=(302±4) · 10−4.