The alpha‐decay of mass‐separated 225Th

The alpha‐decay of 225Th (T1/2=8mn) to 221Ra levels was investigated. Mass‐separated 225Th sources were produced with the ORSAY‐ISOCELE facility. The selectivity in Z was obtained using fluorination techniques. Single α and γ spectra and α‐γ coincidences were simultaneously recorded.The low‐lying levels of 221Ra are interpreted as two parity‐coupled bands (Kπ=5/2± and 2/3±) expected for octupole deformed odd‐nuclei in the Z=88, N=134 region.