Superallowed β-Decay Branching Ratio Measurement of 26Si
Abstract
As part of the continued effort to test the unitarity of the Cabbibo-Kobayashi-Maskawa
matrix, the branching ratio for the Tvz = -1 superallowed 0^+ → 0^+ positron-emitter ^26Si was
measured precisely for the first time. Since the QvEC value, 4840.86(10) keV, and half-life,
2245.3(7) ms, are known precisely, the branching ratio is all that is required to obtain a
precise ft value. This completes the second pair of mirror superallowed transitions, ^26Si → ^26mAl and 26mAl → ^26Mg. A previous measurement of the mirror transitions, ^38Ca → ^38mK
and ^38mK → ^38Ar, showed that the ratio of mirror ft-values is very sensitive to the model
used to calculate the small isospin symmetry-breaking corrections required to extract Vvud. In
calculating this correction, both Woods-Saxon and Hartree-Fock radial wave functions have
been used, with the experimental results from the first pair favoring Woods-Saxon. The
result for the A = 26 mirror pair demonstrates that this conclusion can be generalized.
Citation
Bencomo, Miguel (2018). Superallowed β-Decay Branching Ratio Measurement of 26Si. Doctoral dissertation, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /174335.