High-spin positive-parity states in 179Hf studied by the 180Hf(τ, α)179Hf reaction AT 32 MeV

Full angular distributions are presented for states populated in the reaction 180Hf(τ, α)179Hf at 32 MeV beam energy. Positive-parity states associated with the i132 unique parity intruder orbital are given special attention. Thus, angular distributions for the five first members of the [62492] groundstate sequence are given, as well as for a number of more highly excited states, some being new assignments. The distribution of l = 6 transfer strength is quite characteristic, two 132+ states being substantially more populated than the rest. The characteristic features of the data are explained by a quasiparticle-rotor calculation employing deformed Woods-Saxon orbitals, but only if the hexadecapole shape parameter of the nuclear potential is β4 ∼ −0.08. The often anomalous differential cross sections for Iπ ≠ 132+ band members are well accounted for by a rotor model CCBA calculation employing transfer form factors extracted from the orbitals of the deformed Woods-Saxon field, and including non-adiabatic Coriolis mixing effects.