DELTA-J=1 BAND STRUCTURES ON NS-ISOMERIC STATES IN ODD MASS TE-117, TE-119, TE-121 NUCLEI

In117Te,119Te and121Te isomeric states with Jπ=5/2+, 5/2+ and 7/2+ and half-lives of 19.1(9)ns, 2.2(2) ns and 86(6) ns, respectively, have been identified at low excitation energies using (α, 2 n) reactions on enriched115-119Sn targets. Positive parity ΔJ=1 bands built on these isomeric states have been observed up to 17/2+. The states are interpreted as members of rotational bands built on deformation driving 5/2+ [402] and 7/2+ [404] Nilsson orbitals which overcome the N=64 subshell gap. The irregular level spacings and electromagnetic properties of the bands are well explained in Coriolis calculations. The moment of inertia parameter as function of collective angular momentum has been derived from the doubly even Te cores. The hindrance of the band head deexcitation may be caused by shape fluctuations of these transitional nuclei. © 1979 Springer-Verlag.