High-precision branching-ratio measurement for the superallowed β+ emitter $^{26}$Al$^{m}$
Abstract
A high-precision branching-ratio measurement for the superallowed β + emitter 26Alm was performed at the TRIUMF-ISAC radioactive ion beam facility. An upper limit of 12 ppm at 90% confidence level was found for the second forbidden β + decay of 26Alm to the 2+ 1 state at 1809 keV in 26Mg. An inclusive upper limit of 15 ppm at 90% confidence level was found when considering all possible nonanalog β + /EC decay branches of 26Alm, resulting in a superallowed branching ratio of 100.0000+0 −0.0015%.