Intruder negative-parity states of neutron-rich 33Si

Yrast states in the neutron-rich 1433Si19 nucleus have been studied using binary grazing reactions produced by the interaction of a 215-MeV beam of 36S ions with a thin 208Pb target. An experimental setup that combines the large-acceptance magnetic spectrometer PRISMA and the high-efficiency γ-ray detection array CLARA was used in the experiment. Four new γ-ray photopeaks at energies of 971, 1724, 1772, and 2655 keV were observed and assigned to the 33Si level scheme. The experimental level scheme is compared with the results of 1ℏω p-sd-pf large-scale shell-model calculations using the recently developed PSDPFB effective interaction; good agreement is obtained. The structure of the populated states of 33Si is discussed within the context of an odd neutron coupled to states of the 32Si core.