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Volume 281 - The 26th International Nuclear Physics Conference (INPC2016) - Fundamental Symmetries and Interactions in Nuclei – Monday 12
High-precision Half-life And Branching Ratio Measurements For Superallowed β+ Emitters At TRIUMF-ISAC
M. Dunlop,* A.T. Laffoley, R. Dunlop, C. Andreoiu, R.A. E. Austin, G.C. Ball, T. Ballast, P.C. Bender, H. Bidaman, V. Bildstein, B. Blank, H. Bouzomita, S. Chagnon-Lessard, A. Chester, D.S. Cross, G. Deng, A. Diaz Varela, P. Finlay, A.B. Garnsworthy, P.E. Garrett, J. Giovinazzo, J. Glister, G.F. Grinyer, J. Grinyer, G. Hackman, B. Hadinia, D.S. Jamieson, B. Jigmeddorj, S. Ketelhut, D. Kisliuk, K.G. Leach, J.R. Leslie, A.D. MacLean, D.W. Miller, W.J. Mills, M. Moukaddam, J. Park, A.J. Radich, M.M. Rajabali, E.T. Rand, K. Starosta, C.E. Svensson, E.R. Tardiff, J.P. Thomas, I.S. Towner, S. Triambak, J. Turko, C. Unsworth, A. Valencik, P. Voss, Z.M. Wang, S. Williams, J. Wong, S.W. Yates, E.F. Zganjar
*corresponding author
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Pre-published on: 2017 May 04
Published on: 2017 May 09
High precision measurements of the $ft$ values for superallowed Fermi $\beta$ transitions between $J^\pi~=~0^+$ 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 ($V_{ud}$) 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, $^{10}$C, to the heaviest case for which precision data are currently available, $^{74}$Rb. These experiments have been performed using a 4$\pi$ continuous-flow gas proportional $\beta$ counter, the 8$\pi$ $\gamma$-ray spectrometer, and, most recently, the new high-efficiency GRIFFIN $\gamma$-ray spectrometer. In this paper, recent highlights from the superallowed Fermi $\beta$ decay program at TRIUMF will be summarized, including high-precision half-life measurements for all three of the lightest superallowed emitters, $^{10}$C, $^{14}$O, and $^{18}$Ne, with the greatest sensitivity to a potential weak scalar current contribution, as well as high-precision branching-ratio measurements for the heavy superallowed emitters $^{62}$Ga and $^{74}$Rb.
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