G. Bonsignori

High-spin states in 137Nd: A large variety of collective rotations

Abstract The high-spin structure of 137Nd has been studied through the 110Pd(30Si,3n) and the 123Sb(19F,5n) reactions at beam energies of 125 and 97 MeV, respectively. A very complex level scheme has been established up to spin 97 2 + and 23.9 MeV of excitation energy. Regular bands are observed at high-spin, consisting of either M1 and E2 crossover transitions, or of stretched M1 or E2 transitions. Calculations have been performed in the framework of the interacting boson-fermion model with broken pairs for the relatively strong ΔI = 1 regular structures observed above spins 27 2 − and 31 2 − , which are well described by the (νh 11 2 ) 3 and νh 11 2 ⊗(πh 11 2 ) 2 configurations, respectively.

Dipole rotational band in137Nd

A dipole band with regular energy spacings has been identified in the nucleus137Nd built on aI=33/2 state atEx=5.60 MeV. The Doppler shift attenuation method analysis of a backed-target experiment allowed to extract the lifetimes of the band levels, which are of the order of 1 W. u., The resulting large B(M1) values, together with the high aligned angular momentum suggest a five-quasiparticle configuration (involving twoh11/2 protons and twoh11/2 neutrons).

One and three fermion states in the interacting boson fermion model: High-spin states in191,193Hg

The structure of high-spin states in the transitional nuclei191,193Hg is described in the framework of the interacting boson fermion model with one broken pair. The results of model calculation reproduce in detail the structure of yrast states up toJ=49/2+ħ, including the first backbending, and the two lowest three-neutron negative parity bands.