A note on the higher order effects in the nonunique first forbidden beta decays of 125Sb, 186Re and 152Eu

An attempt is made to determine the higher order effects in the nonunique first forbidden beta decays of 125Sb, 186Re and 152Eu with matrix element parameters obtained using Simms' formalism. The experimental values of the CVC ratio are not in agreement with Fujita's estimate and support the view that the neglection of the nondiagonal matrix elements in the operator for the Coulomb potential is not valid. From the experimental values, limits are set on the magnitude of the correction factors and these provide a measurement of the higher order matrix element parameters.