High-Precision Superallowed Fermi $\beta$ Decay Measurements at TRIUMF-ISAC
COFFEE_KLATCH · Invited
Abstract
High-precision measurements of the $ft$-values for superallowed Fermi $\beta$ decays between nuclear isobaric analogue states provide demanding tests of the electroweak Standard Model, including confirmation of the Conserved Vector Current hypothesis at the level of $1.2 \times 10^{-4}$, the most stringent limits on weak scalar currents, and the most precise determination of the $V_{ud}$ element of the CKM quark-mixing matrix. The Isotope Separator and Accelerator (ISAC) facility at TRIUMF produces high-quality beams of several of the superallowed emitters with world-record intensities and hosts a suite of state-of-the-art spectrometers for the measurement of superallowed half-lives, branching ratios, $Q_{EC}$ values, and charge-radii. Recent highlights from the superallowed program at ISAC, including high-precision half-life measurements for the light superallowed emitters $^{10}$C, $^{14}$O, $^{18}$Ne, and $^{26m}$Al and branching-ratio measurements for the heavy superallowed emitters $^{62}$Ga and $^{74}$Rb will be presented. The impact of these measurements on tests of the Standard Model, and future developments in the superallowed program at ISAC with the new high-efficiency GRIFFIN $\gamma-ray$ spectrometer, will be discussed.
*Research supported by the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, and the Canada Research Chairs Program. TRIUMF receives federal funding via the National Research Council of Canada.
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