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. © 2013 American Physical Society.
Publication Source (Journal or Book title)
Physical Review C - Nuclear Physics
Dunlop, R., Ball, G., Leslie, J., Svensson, C., Towner, I., Andreoiu, C., Chagnon-Lessard, S., Chester, A., Cross, D., Finlay, P., Garnsworthy, A., Garrett, P., Glister, J., Hackman, G., Hadinia, B., Leach, K., Rand, E., Starosta, K., Tardiff, E., Triambak, S., Williams, S., Wong, J., Yates, S., & Zganjar, E. (2013). High-precision branching-ratio measurement for the superallowed β+ emitter 74Rb. Physical Review C - Nuclear Physics, 88 (4) https://doi.org/10.1103/PhysRevC.88.045501