Energy dependence of β-(circularly polarized γ) correlations

Abstract An apparatus was constructed for measuring γ-(circularly polarized γ) correlations simultaneously as a function of the β-energy and the angle θ between β- and γ-rays. The circular polarization of the γ-radiation is detected by means of Compton forward scattering. In order to get optimum experimental conditions, two different set-ups were chosen for investigating allowed and first-forbidden β-transitions, respectively. For the study of allowed transitions, a conventional set-up was constructed using a cylindrical magnet and one β-counter only. The experimental set-up for the investigation of first-forbidden transitions consists of two β-counters for the two mean angles θ = 140° and θ = 160° and a 100° cylindrical segment magnet. The β-energy dependence is recorded by a multi-channel analyser divided into four quarters. With the set-up for allowed transitions, the ( υ / c ) dependence of the β-(circularly polarized γ) correlations of the allowed β-transitions of 22 Na and 60 Co was investigated for the energy range of E β > 44 keV. The results are in good agreement with the predicted υ / c dependence. With the set-up for first-forbidden decays, the energy dependence of the first-forbidden β-transition of 86 Rb was measured.