Precision half-life measurement of P29

A new precision half-life measurement of P-29 was conducted using the TwinSol beta-counting station at the University of Notre Dame Nuclear Science Laboratory. The resulting value of t(1/2)(new) = 4.1055(44) s is the most precise P-29 half-life measurement to date. Utilizing this measurement and reevaluating the world data leads to a new world average of t(1/2)(world) = 4.1031(58) s, which improves the Birge ratio from 3.11 to 1.45 and is 2.3 times more precise than the previous world value. The new Cabibbo-Kobayashi-Maskawa matrix element V-ud for P-29 shifts closer into agreement with the superallowed pure Fermi value. The uncertainty in the mixed transition value of V-ud, however, is still dominated by the Fermi to Gamow-Teller mixing ratio rho. Using the new world half-life and assuming the validity of the standard model, a new predicted value for rho and its associated correlation parameters have been evaluated in order to guide future determination of rho.