Fermi superallowed β+ decays and T=1 ground states of heavy odd-odd N=Z nuclei
Garcés Narro J., Longour C., Regan PH., Blank B., Pearson CJ., Lewitowicz M., Miehé C., Gelletly W., Appelbe D., Axelsson L., Bruce AM., Catford WN., Chandler C., Clark RM., Cullen DM., Czajkowski S., Daugas JM., Dessagne P., Fleury A., Frankland L., Giovinazzo J., Greenhalgh B., Grzywacz R., Harder M., Jones KL., Kelsall N., Kszczot T., Page RD., Reed AT., Sorlin O., Wadsworth R.
The β+-decay half-lives of the neutron-deficient odd-odd N=Z nuclei 74Rb, 78Y, 82Nb, and 86Tc have been measured following the fragmentation of a primary 92Mo beam at an energy of 60 MeV per nucleon at the GANIL laboratory, France. This was achieved by correlating β+ decays with the implantation of unambiguously identified fragments at the final focus of the LISE3 separator. The deduced log10ft1/2 values are consistent with 0+→0+, Fermi superallowed transitions, which together with the measured β+-detection efficiencies, suggest T=1, Iπ=0+ ground states for these odd-odd N=Z nuclei. These data represent the heaviest N=Z systems for which Fermi superallowed decays have been established.