Rotational bands in a transitional nucleus: 151Sm

The 150Nd(α, 3n)151Sm reaction has been used to populate states in 151Sm. A cascade of E2 transitions which belong to a very distorted positive parity band up to, the spin 332+ member is observed. Unlike other studies of this positive parity band in N = 89 rare earth nuclei, many other transitions feed the states with I+12 odd. Some of these originate in states which seem to constitute the other half of the positive parity band with I+12 even. The rotational band built on the 112− [505] state is observed up to spin 292− and possibly spin 312−. In addition to the previously established levels at 65.83 (72−) and 294.8 (92−) keV, four more levels belonging to the ground-state band have been found. Another group of levels decay into the 92− level at 175 keV and are possibly the result of an h92 particle coupled to the 150Sm core. Several other levels, which decay to well-known negative parity states, are also populated below 1 MeV excitation energy.