6533b82ffe1ef96bd12946a1

RESEARCH PRODUCT

Shell model and octupole states in148Gd from in-beam experiments

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Through (α, 4n) and (τ, 3n) reactions the high-spin states in the two-neutron nucleus148Gd were populated up toI π=21− at 7.2 MeV, including numerous states above the yrast line. The148Gd energy spectrum is interpreted in terms of the spherical shell model. Identification of the (νf 7/2 i 1 3/2)10− state gives the νi 13/2 single particle energy free of octupole admixtures as 2.1(1) MeV. Eight high-spin states between 1.2 and 3.7 MeV were identified as the couplings of the two valence-particles to the146Gd octupole phonon, and three above-lying levels are assigned as double-octupole excitations including a 12+ state which decays by anE3-E3 stretched cascade. All these octupole levels can be quantitatively predicted from the one-particle x phonon spectrum of147Gd. The high-spin states above 3 MeV are four-quasiparticle excitations ofπ +1 π −1 ν 2 andπ 2 ν 2 type and their energies are in good accord with shell model estimates.