The nuclear structure of Fr-227

Abstract

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.