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. TriambakS. J. Williams, J. Wong, S. W. Yates, E. F. Zganjar

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


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 B 0=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 Ft̄ 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.

Original languageEnglish
Article number045501
JournalPhysical Review C - Nuclear Physics
Issue number4
StatePublished - Oct 1 2013

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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