Spectroscopie du noyau 139Ce

Abstract

High-spin states in 139Ce have been populated by the 130Te(14C,5n) reaction, using ORGAM array installed at IPN Orsay. The level scheme has been extended to 43/2 ħ in spin and ~ 8 MeV in energy, including a new dipole band. The multipolarity has been measured by the ''Directional Correlation from Oriented states of nuclei'' (DCO) and anisotropy ratios, and the parity of several states has been changed from negative to positive. Extended shell-model calculations have been used to investigate the structure of the observed states. The good agreement of the shell-model calculations with the experimental level scheme supports the spin-parity assignment to low- and medium-spin states. The dipole band configuration was investigated using the CNS and TAC models. The π1h211/2⊗ν1h-111/2 configuration with a deformation of (ε2 = 0.12, γ = 0°) and rotation around a tilted axis with θ ≈ 70°, reproduces best the experimental aligned spins.