A study of levels populated in 166Er by the (d, t) reaction

The reaction 167Er(d, t)166Er has been studied using 12 MeV deutrons. The triton spectra were measured at lab angles of 60°, 90° and 125° using a broad-range heavy-particle spectrograph. The cross sections for exciting the members of the rotational band built on the Kπ = 2− state at 1460 keV indicate that the two-neutron configuration {7/2+[633], 3/2−[521]}2− constitutes ≈50% of this band. This result is in good agreement with the predicted value of 58% for the contribution of this configuration to the Kπ = 2− octupole vibration in 166Er and thus provides further empirical evidence for the validity of the microscopic theory of collective vibrational excitations in deformed even nuclei. The population of the rotational bands built on the ground state and the levels at 787 and 1572 keV are consistent with previous assignments of the nature of these states.