High-precision branching-ratio measurement for the superallowed β+ emitter 74Rb

R. Dunlop, G. C. Ball, J. R. Leslie, C. E. Svensson, I. S. Towner, C. Andreoiu, S. Chagnon-Lessard, A. Chester, D. S. Cross, P. Finlay, A. B. Garnsworthy, P. E. Garrett, J. Glister, G. Hackman, B. Hadinia, K. G. Leach, E. T. Rand, K. Starosta, E. R. Tardiff, S. Triambak, S. J. Williams, J. Wong, S. W. Yates, and E. F. Zganjar
Phys. Rev. C 88, 045501 – Published 1 October 2013

Abstract

A high-precision branching-ratio measurement for the superallowed β+ decay of 74Rb was performed at the TRIUMF Isotope Separator and Accelerator (ISAC) radioactive ion-beam facility. The scintillating electron-positron tagging array (SCEPTAR), composed of 10 thin plastic scintillators, was used to detect the emitted β particles; the 8π spectrometer, an array of 20 Compton-suppressed HPGe detectors, was used for detecting γ rays that were emitted following Gamow-Teller and nonanalog Fermi β+ decays of 74Rb; and the Pentagonal Array of Conversion Electron Spectrometers (PACES), an array of 5 Si(Li) detectors, was employed for measuring β-delayed conversion electrons. Twenty-three excited states were identified in 74Kr following 8.241(4)×108 detected 74Rb β decays. A total of 58 γ-ray and electron transitions were placed in the decay scheme, allowing the superallowed branching ratio to be determined as B0=99.545(31)%. Combined with previous half-life and Q-value measurements, the superallowed branching ratio measured in this work leads to a superallowed ft value of 3082.8(65) s. Comparisons between this superallowed ft value and the world-average-corrected Ft¯ value, as well as the nonanalog Fermi branching ratios determined in this work, provide guidance for theoretical models of the isospin-symmetry-breaking corrections in this mass region.

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  • Received 15 November 2012

DOI:https://doi.org/10.1103/PhysRevC.88.045501

©2013 American Physical Society

Authors & Affiliations

R. Dunlop1,*, G. C. Ball2, J. R. Leslie3, C. E. Svensson1, I. S. Towner4, C. Andreoiu5, S. Chagnon-Lessard1, A. Chester5, D. S. Cross5, P. Finlay1,†, A. B. Garnsworthy2, P. E. Garrett1, J. Glister2, G. Hackman2, B. Hadinia1, K. G. Leach1, E. T. Rand1, K. Starosta5, E. R. Tardiff2, S. Triambak2,6, S. J. Williams2, J. Wong1, S. W. Yates7, and E. F. Zganjar8

  • 1Department of Physics, University of Guelph, Guelph, Ontario, Canada N1G 2W1
  • 2TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3
  • 3Department of Physics, Queens University, Kingston, Ontario, Canada K7L 3N6
  • 4Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA
  • 5Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
  • 6Department of Physics, University of Western Cape, P/B X 17 Bellville, 7535, South Africa
  • 7Departments of Chemistry and Physics & Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055, USA
  • 8Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803-4001, USA

  • *rdunlop@uoguelph.ca
  • Present address: Instituut voor Kern-en Stralingsfysica, K, V. Leuven, Celestignenlaan 200D, B-3001 Leuven, Belgium.

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Vol. 88, Iss. 4 — October 2013

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