OCTUPOLE CORRELATIONS IN TH-225

The nuclear structure of 225Th has been studied using the reaction 226Ra(α, 5n) 225Th at a beam energy of 50 MeV. In-beam γγ, e-e-, e-n and e-γ coincidences have been measured, along with γ-ray and electron intensities, and these have been used to establish a decay scheme up to spin 39/2h{stroke} and excitation energy 2494 keV. Parity doublets have been observed, forming two "quasimolecular bands", along with enhanced E1 transitions linking states of opposite parity. γ-branching ratios have been measured and an average value of |D0/Q0| = (0.51±0.06)×10-3fm-1 has been deduced. The results are compared with calculations incorporating odd multipole degrees of freedom in the description of the nuclear shape. © 1990 Elsevier Science Publishers B.V.