High-spin spectroscopy and shell-model interpretation of the N < 126 radium isotopes Ra 212 and Ra 213 HIGH-SPIN SPECTROSCOPY and SHELL-MODEL ... T. PALAZZO et al.

The level structures of Ra212 and Ra213 have been established via time-correlated γ-ray spectroscopy following the Pb204(C12,4n)Ra212 and Pb204(C13,4n)Ra213 reactions. In Ra212, levels up to ∼6.2MeV were identified and firm spin-parity assignments were achieved to a Jπ=19+ isomer with a mean life of 31(3) ns. For Ra213 the corresponding values were ∼4.5MeV in excitation energy and Jπ=33/2+. Two isomeric states with Jπ=23/2+, τ=27(3) ns and Jπ=33/2+, τ=50(3) ns were discovered in Ra213. The experimental data were compared with semiempirical shell-model calculations, which allowed dominant configurations to be assigned to most of the observed levels.