Precision Half-life Measurement of ³³Cl

For the past decade our understanding of fundamental symmetries has really been expanded thanks to new precision measurements. Of particular interest is that the extraction of Vud from superallowed pure fermi decays has shown that the CKM matrix may not be unitary. To confirm this result, an international campaign is underway to extract V_ud using precise determinations of ft values for superallowed mixed transitions between mirror nuclides. Calculation of ft values requires the half-life, branching ratio, and Q value. The ³³Cl decay half-life is derived from a series of old measurements. The life-time was determined counting β particles from the decay of the implanted ³³Cl. The ³³Cl beam was produced via the ³²S(d, n) transfer reaction and separated by the TwinSol facility of the Nuclear Science Laboratory of the University of Notre Dame. The progress on the ³³Cl analysis will be presented.