Nuclear orientation of152,154Tb in gadolinium

The anisotropy in the directional distribution of gamma-rays from the decay of^152,154Tb oriented in a gadolinium matrix at low temperatures, has been measured at the angles of 0 and π/2 with respect to the applied magnetic field direction at temperature of (15±1) mK. Unambiguous values of spin have been deduced for several levels in¹⁵²Gd. Multipole mixing ratios of many gamma-ray transitions occurring in¹⁵²Gd have been found and results are compared with the similar transitions in^150,154,156Gd and they are discussed in terms of the rotational-vibrational model and dynamic deformation theory based on the Strutinsky method. Our results confirm the spin value of 0 for 21·4 h isomer in¹⁵⁴Tb 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 in¹⁵⁴Gd.