High-spin spectroscopy and shell-model interpretation of the N < 126 radium isotopes Ra212 and Ra<

Abstract

The level structures of 212 Ra and 213 Ra have been established via time-correlated γ-ray spectroscopy following the 204 Pb( 12 C,4n) 212 Ra and 204 Pb( 13 C,4n) 213 Ra reactions. In 212 Ra, levels up to ∼ 6.2 MeV were identified and firm spin-parity assignments were achieved to a J π = 19 + isomer with a mean life of 31(3) ns. For 213 Ra the corresponding values were ∼ 4.5 MeV in excitation energy and J π = 33/2 + . Two isomeric states with J π = 23/2 + , τ = 27(3) ns and J π = 33/2 + , τ = 50(3) ns were discovered in 213 Ra. The experimental data were compared with semiempirical shell-model calculations, which allowed dominant configurations to be assigned to most of the observed levels.

The Heavy Ion Accelerator Facility: Research Achievements and Aspirations

“…Refs. [15,16] and references therein). Highlights of recent work include the addition of LaBr 3 detectors for lifetime measurements on the subnanosecond time scale, and experiments to eliminate possible alternative explanations of recent evidence of isomer depletion due to nuclear excitation by electron capture [17].…”