Atomic Effects on the TritiumftValue

Abstract

Atomic effects on the tritium $\mathrm{ft}$ value including bound-state decay, imperfect wave-function overlap, screening, and electron exchange are considered for each of the species ${\mathrm{T}}^{+}$, T, ${\mathrm{T}}_2$, and ${\mathrm{T}}^{-}$. Corrections to the $f$ value are tabulated and can be combined to extract an improved estimate for the axial-vector matrix element in tritium $\beta$ decay.