Level structure in 117Sb investigated in the decay of the isomeric three-quasiparticle state

Abstract

The level structure of 117Sb was investigated in the reactions 115In(α, 2nγ) 117mSb, 117Sn(d, 2nγ) 117mSb and 117Sn(p, nγ) 117mSb. In order to confirm level sequences and to assign spins and parities to levels populated in the decay of the isomeric three-particle state T 1 2 = 340 μs), prompt and delayed γ-ray spectra, lifetimes, γ-γ coincidences, γ-ray angular distributions, conversion electrons and excitation functions were measured. The spin 25 2 + of the isomeric state can be explained by the three-particle configuration [ π( d 5 2 ); v( h 11 2 ) 2 10 +] 25 2 + . This is supported by the experimentally determined g-factor of g = O.115 ± 0.006. Other levels in 117Sb can be interpreted as particle states coupled to anharmonic vibrations of the core. The existence of an excited 9 2 +[404] quasirotational band is experimentally proved and is supported by calculations of the equilibrium deformation.