High-precision half-life measurement for the superallowed [beta][superscript +] emitter [superscript 26]Al[superscript m]

Abstract

A high-precision half-life measurement for the superallowed [beta][superscript +] emitter [superscript 26]Al[superscript m] was performed at the TRIUMF-ISAC radioactive ion beam facility yielding T[subscript 1/2] = 6346.54 [plus or minus] 0.46[subscript stat] [plus or minus] 0.60[subscript syst] ms, consistent with, but 2.5 times more precise than, the previous world average. The [superscript 26]Al[superscript m] half-life and f t value, 3037.53(61) s, are now the most precisely determined for any superallowed [beta] decay. Combined with recent theoretical corrections for isospin-symmetry-breaking and radiative effects, the corrected F t value for [superscript 26]Al[superscript m], 3073.0(12) s, sets a new benchmark for the high-precision superallowed Fermi [beta]-decay studies used to test the conserved vector current hypothesis and determine the V[subscript ud] element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix.