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High-precision half-life determination for Na-21 using a 4 pi gas-proportional counter
Journal Contribution - Journal Article
A high-precision half-life measurement for the superallowed β + transition between the isospin T = 1/2 mirrornuclei 21Na and 21Ne has been performed at the TRIUMF-ISAC radioactive ion beam facility yielding T1/2 = 22.4506(33) s, a result that is a factor of 4 more precise than the previous world-average half-life for 21Na andrepresents the single most precisely determined half-life for a transition between mirror nuclei to date. The contribution to the uncertainty in the 21Na Ft mirror value due to the half-life is now reduced to the level of the nuclear structure-dependent theoretical corrections, leaving the branching ratio as the dominant experimental uncertainty.
Journal: Physical Review C
Number of pages: 6