Nuclear orientation of 152Tb, 154Tb in gadolinium

Anisotropy in the directional distribution of gamma-rays from the decay of 152Tb, 154Tb oriented in a gadolinium matrix at low temperatures was measured at angles of 0 and π/2 with respect to the applied magnetic field direction at a temperature of (15+-1) mK. Unambiguous spin values were deduced for several levels in 152Gd. The multipole mixing ratios of many gamma-ray transitions occurring in 152Gd were found and the results were compared with similar transitions in 150Gd, 154Gd, 156Gd. They are discussed in terms of the rotational-vibrational model and dynamic deformation theory based on the Strutinsky method. The results confirm the spin value of 0 for the 21.4 h isomer of 154Tb and they establish the spin value of 3 for the 2277.0 and 2336.1 keV levels and the spin value of 4 for the 2416.3 keV level of 154Gd. (author)