Spectroscopy of 221 Th

A positive and a negative parity band in221Th have been investigated via the208Pb(16O, 3n)221Th reaction. Strong E1 transitions compete with stretched E2 transitions deexciting levels of alternating parity. The measured averaged =2.6 · 10−6 fm−2 is similar to that observed in neighbouring nuclei. The level scheme may be interpreted assuming an octupole deformed core.