High-precision half-life determination for the superallowed $\beta^+$ emitter $^{62}$Ga
G. F. Grinyer, P. Finlay, C. E. Svensson, G. C. Ball, J. R. Leslie, R. A. E. Austin, D. Bandyopadhyay, A. Chaffey, R. S. Chakrawarthy, P. E. Garrett, G. Hackman, B. Hyland, R. Kanungo, K. G. Leach, C. M. Mattoon, A. C. Morton, C. J. Pearson, A. A. Phillips, J. J. Ressler, F. Sarazin, H. Savajols, M. A. Schumaker, and J. Wong

The half-life of the superallowed $\beta^+$ emitter $^{62}$Ga has been measured at TRIUMF's ISAC facility using a fast-tape-transport system and 4$\pi$~continuous-flow gas proportional counter to detect the positrons from the decay of $^{62}$Ga to the daughter $^{62}$Zn. The result, $T_{1/2}$~=~116.100~$\pm$~0.025~ms, represents the most precise measurement to date (0.022$\%$) for any superallowed $\beta$~decay half-life. When combined with 6 previous measurements of the $^{62}$Ga half-life, a new world average of $T_{1/2}$~=~116.121~$\pm$~0.021~ms is obtained. This new half-life measurement results in a 20$\%$ improvement in the precision of the $^{62}$Ga superallowed $ft$ value while reducing its mean by 0.9$\sigma$ to $ft$~=~3074.3(1.2)~s. The impact of this half-life measurement on precision tests of the CVC hypothesis and isospin symmetry breaking corrections for $A$~$\geq$~62 superallowed decays is discussed.

© 2008 The American Physical Society.