High-Precision Branching Ratio Measurement for the Superallowed + Emitter 74Rb
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Date
2013
Journal Title
Journal ISSN
Volume Title
Publisher
American Physical Society
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 electronpositron
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 f t value
of 3082.8(65) s. Comparisons between this superallowed f t 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.
Description
Keywords
Physical science, Branching-ratio measurement, TRIUMF Isotope Separator and Accelerator (ISAC), Scintillating electronpositron
tagging array (SCEPTAR)
Citation
Dunlop, R. et al. (2013). High-precision branching-ratio measurement for the superallowed ?+ emitter 74Rb. Physical Review C, 88(4): 1-27