W. Lourens

The decay of 14.6 h 86Y

Abstract The radioactive decay of 86Y has been investigated using beta and gamma spectrometers, a gamma-gamma directional correlation arrangement and gamma-gamma and beta-gamma coincidence set-ups. Six positon branches and twenty-nine gamma rays have been found. A decay scheme is put forward and spin and parity assignments are made for several levels in 86Sr. This disintegration scheme is compared with previously reported experimental results and with theoretical predictions.

Beta-gamma circular polarization in the decay of 48Sc

Abstract The beta-gamma circular polarization correlation in 48 Sc between the 654 keV allowed beta transition and the 1040, 1314 and 983 keV E2 gamma rays has been measured by means of forward Compton scattering. The result A = + (0.11 ± 0.06) is in agreement only with a spin of 6 + for the 48 Sc ground state. A value of x 2 > 32 is derived for the ratio of Gamow-Teller to Fermi intensities if it is assumed that the beta transition is pure or almost pure Gamow-Teller. The experimental result is in agreement with our earlier measurements.

M1 — E2 Admixtures in Transitions from Beta- and Gamma Levels in 152 Sm

There has been much interest in recent years1–4) in the detailed properties of beta- and gamma levels in intermediate nuclei since they exhibit large deviations from both the harmonic vibrator model and the rigid rotator model. A perturbation expansion around the equilibrium shape is therefore not allowed in these cases. Special theoretical techniques have been developed for the study of intermediate nuclei. For a number of nuclei, Kumar4) has recently calculated the M1 – E2 — mixing occurring in transitions from beta- and gamma vibrational levels. We decided to check his results experimentally on 152Sm since that might contribute to showing the potentiality of the applied theoretical techniques. It is true that measurements of the M1 – E2 mixing ratios in transitions occurring in 152 Sm have been performed by other groups (ref. 5); however, we felt that for a proper judgement of the theoretical calculations of the small M1 — admixtures the experimental accuracy had to be improved considerably. For instance, the amplitude mixing ratio δ for the 689 keV 2β → 2 transition has been measured by two groups applying Coulomb excitation techniques. They report δ = 67+∞ −54 (ref. 3) and δ = 13+28 −5 (ref. 6).