Fourth forbidden beta decays of50V

The half lives ofβ ^? decay ande ^? capture in theΔJ=4 transitions of⁵⁰V were calculated in the formulation of Behrens and Schülke. The expression of formulas for these half lives are divided into two parts. The ones are common factors which depend on the lepton wave functions only. The other parts are nuclear parameters which change their values by choosing suitable nuclear models. We tabulated the numerical values of these common factors. As an example, we evaluated these parameters in a single particle shell model, and obtained the half lives 9.04×10¹⁷ years and 1.51×10¹⁶ years for theβ ^? decay ande ^? capture, respectively. The recent experimental data measured by A.J. Pape et al. aret _1/2>7.0×10¹⁷ years for theβ ^? decay andt _1/2>8.8×10¹⁷ years for thee ^? capture. In the case of thee ^? capcure, the screening effects of the other orbital electrons were properly taken into account.