High-precision half-life and branching ratio measurements for superallowed β+ Emitters At TRIUMF-ISAC

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Conference Proceeding

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High precision measurements of the ft values for superallowed Fermi β transitions between Jπ = 0+ isobaric analogue states allow for stringent tests of the electroweak interaction described by the Standard Model. These transitions provide an experimental probe of the Conserved-Vector-Current hypothesis, enable the most precise determination of the up-down (Vud) element of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix, and allow one to set stringent limits on the existence of scalar currents in the weak interaction. An extensive program of superallowed branching-ratio and half-life measurements at TRIUMF's Isotope Separator and Accelerator (ISAC) facility has covered the full range of superallowed emitters, from the lightest case, 10C, to the heaviest case for which precision data are currently available, 74Rb. These experiments have been performed using a 4π continuous-flow gas proportional β counter, the 8π γ-ray spectrometer, and, most recently, the new high-efficiency GRIFFIN γ-ray spectrometer. In this paper, recent highlights from the superallowed Fermi β decay program at TRIUMF will be summarized, including high-precision half-life measurements for all three of the lightest superallowed emitters, 10C, 14O, and 18Ne, with the greatest sensitivity to a potential weak scalar current contribution, as well as high-precision branching-ratio measurements for the heavy superallowed emitters 62Ga and 74Rb.

Publication Source (Journal or Book title)

Proceedings of Science

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