The γ-rays following the β- decay of Rn-227 have been investigated by means of γ-ray singles and γγ-coincidence measurements using an array of 12 Compton-suppressed Ge detectors. The fast-timing βγγ(t) method has been used to measure six level lifetimes. Multipolarities of 32 transitions in Fr-227 have been established by measuring conversion electrons with a mini-orange electron spectrometer. Most of the observed transitions have been placed in a level scheme comprising 38 excited states of Fr-227, The low-lying levels are interpreted in terms of seven rotational bands. The observed E1 strengths for two transitions connecting the K-π = 3/2(±) bands are consistent with the transitional character of Fr-227, and confirm the presence of octupole correlations in this nucleus.

This work was supported in part by the Natural Sciences and Engineering Research Council of Canada, the Norwegian Research Council, the Polish Scientific Research Committee under grant KBN-2-P03B-001-11, the Spanish CICYT under contracts AEN94-0833-C02-01 and AEN94-0833-C02-02, the Swedish Natural Science Research Council, and the UK Engineering and Physical Sciences Research Council. J.F.C.C. and J.F.S. acknowledge receipt of EPSRC studentships.

26 pages, 4 tables, 10 figures.-- PACS nrs.: 21.10.−k; 23.20.−g; 23.20.Lv; 23.20.Nx.

Peer reviewed