High spin band structure of 3885 Sr47

Abstract

High spin states in the Sr85 nucleus were populated in the reaction Ge76(13C,4n) at a beam energy of 45 MeV. The γ-γ and γ-γ-γ coincidence measurements have been utilized to establish the level scheme of Sr85 up to Iπ=35/2-. Nearly 50 new γ rays and about 25 new levels were identified and most of the previously known levels confirmed. The spin-parity assignment of the levels was made by using the directional correlations of the oriented nuclei ratios and polarization asymmetry measurements. The shell-model calculations have been performed by using two recent interactions, JUN45 and jj44b, for a detailed comparison between theoretical results and the experimental data obtained in the present work. The shell-model results are in good agreements with the experimental data and are able to explain the various features such as the odd-even staggering well. Tilted axis cranking calculations were also performed to understand the magnetic rotation (MR) phenomenon at higher spins. One of the positive-parity ΔI=1 bands has been assigned a three-quasiparticle (3qp) configuration, which appears to behave like a MR band. A negative-parity band populated up to Iπ=35/2- was also assigned a 3qp configuration at low spin and a five-quasiparticle configuration at high spin; however, it does not exhibit the expected MR features, in contrast to a similar band in the Kr83 nucleus. © 2014 American Physical Society.