B. Hadinia

Far from 'Easy' Spectroscopy with the 8π and GRIFFIN Spectrometers at TRIUMF-ISAC

The 8 pi spectrometer, installed at the TRIUMF-ISAC facility, was the worlds most sensitive gamma-ray spectrometer dedicated to beta-decay studies. A description is given of the 8 pi spectrometer and its auxiliary detectors including the plastic scintillator array SCEPTAR used for beta-particle tagging and the Si(Li) array PACES for conversion electron measurements, its moving tape collector, and its data acquisition system. The recent investigation of the decay of Cs-124 to study the nuclear structure of Xe-124, and how the beta-decay measurements complemented previous Coulomb excitation studies, is highlighted, including the extraction of the deformation parameters for the excited 0(+) bands in Xe-124. As a by-product, the decay scheme of the (7(+)) Cs-124 isomeric state, for which the data from the PACES detectors were vital, was studied. Finally, a description of the new GRIFFIN spectrometer, which uses the same auxiliary detectors as the 8 pi spectrometer, is given.

High-Precision Half-Life Measurements for the Superallowed β+ Emitter

Precision measurements of superallowed Fermi β-decay transitions, particularly for the lightest superallowed emitters ^{10}C and ^{14}O, set stringent limits on possible scalar current contributions to the weak interaction. In the present work, a discrepancy between recent measurements of the ^{10}C half-life is addressed through two high-precision half-life measurements, via γ-ray photopeak and β counting, that yield consistent results for the ^{10}C half-life of T_{1/2}=19.2969±0.0074u2009u2009s and T_{1/2}=19.3009±0.0017u2009u2009s, respectively. The latter is the most precise superallowed β-decay half-life measurement reported to date and the first to achieve a relative precision below 10^{-4}. A fit to the world superallowed β-decay data including the ^{10}C half-life measurements reported here yields b_{F}=-0.0018±0.0021 (68%xa0C.L.) for the Fierz interference term and C_{S}/C_{V}=+0.0009±0.0011 for the ratio of the weak scalar to vector couplings assuming left-handed neutrinos.

^{10}

High precision measurements of the

C: Implications for Weak Scalar Currents

ft

High-precision Half-life And Branching Ratio Measurements For Superallowed β+ Emitters At TRIUMF-ISAC

values for superallowed Fermi

Searching for 0 + states in Cr 50 : Implications for the superallowed β decay of Mn 50

beta

High-Precision Half-Life Measurements for the Superallowed Fermi

transitions between

\beta

J^pi~=~0^+

+ Emitters

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 (

^{14}

V_{ud}