Octupole bands in even isotopes of Ra, Th, U and Pu

Abstract

Many heavy nuclei have low-lying Kπ = 0− bands. Furthermore, several even isotopes of Ra, Th, U and Pu have Kπ = 1− bands with bandhead excitation energies very close to 1 MeV. The E3 transitions from the 0+ ground state to the 3− members of these bands have reduced strengths B(E3; 0+ → 3−) comparable to those measured in the isotopes of Pb. An exotic cluster model with a Pb core is proposed to account for these observations. A good account of the data is given, and higher lying Kπ = 2− and 3− bands are predicted. The intermediate strength quadrupole-quadrupole coupling between cluster and core leads to irregular, inverted doublets in the calculated Kπ = 1− bands.