Possible oblate rotational bands in N=84 nuclides

Strong-coupling rotational bands built on 11/sup -/ (33/2/sup +/ for odd-A) states with configuration ..nu..(i/sub 13/2/, h/sub 9/2/) (..pi..(h/sub 11/2/) ..nu..(i/sub 13/2/, h/sub 9/2/) are off-A) were identified in N=84 nuclei with Z less than or equal to 65. These are the first levels observed in this region with proven oblate deformation. 3 figures

Strength of Coriolis Coupling in actinide nuclei

Coriolis Coupling V/sub cor/ plays an important role in deformed nuclei. V/sub cor/ is proportional to h/sup 2//J(j (j + 1) -..cap omega.. (..cap omega.. + 1))/sup 1/2/ and therefore is particularly significant in the nuclei with large j and low ..cap omega.. Nilsson levels close to Fermi surface: n(i/sub 13/2/) in A = 150 to 170 rare-earth nuclei and p(i/sub 13/2/) and n(j/sub 15/2/) in A greater than or equal to 224 actinide nuclei. Because of larger j (n(j/sub 15/2/) versus n(i/sub 13/2/)) and smaller deformations (..beta.. approx. = 0.22 versus ..beta.. 0.28) it was reasonable to expect that in actinide nuclei Coriolis effects are stronger than in the rare earth nuclei. Recently it was realized that the strength of observed Coriolis effects depends not only on the genuine Coriolis Coupling but also on the interplay between Coriolis ad pairing forces which leads to an interference between the wave functions of two mixing rotational bands. As a consequence the effective interaction V/sub eff/ of both bands is an oscillating function of the degree of shell filling (or chemical potential lambda F). It was shown that in the rare earth nuclei this interference strongly influenced conclusions about the trends in the Coriolis coupling strength and explained many of the observed band-mixing features (the sharpness of back banding curves, details of the blocking effect etc.). From theoretical analysis it was concluded that in the majority of actinide nuclei the effective interaction V/sub eff/ is strong, and therefore the Coriolis band-mixing have to be very strong. In this paper we would like to demonstrate that contrary to these predictions experimental data suggest that Coriolis band mixing in studied actinide nuclei is relatively weak and possibly significantly weaker than in rare earth nuclei