Polarization measurements and high-spin states in 8638Sr48

Abstract

The high-spin states in 86Sr nucleus were populated using the 76Ge(13C, 3n) reaction at a beam energy of 45 MeV. The γ–γ and γ–γ–γ coincidence measurements were used to establish the level scheme up to 10.9 MeV excitation energy and spin Iπ=19+. In our preliminary results reported earlier, a positive-parity dipole (ΔI=1) band based on the 6878-keV level having M1 γ-ray transitions was identified. In the present work, the γ-rays and their sequence have been established for this band. The band may have a magnetic rotational character. The spin-parity of the levels were assigned by measuring the Directional Correlations of the Oriented (DCO) nuclei and the polarization asymmetry. The polarization measurements were performed for the first time for the γ-ray transitions in this nucleus. The experimental band structures were compared with the shell-model calculations using two recent effective interactions, JUN45 and jj44b in the 1p3/2, 0f5/2, 1p1/2, 0g9/2 model space. From the Tilted-Axis Cranking (TAC) calculations, the 4-qp π(g9/2)2⊗ν(g9/2)−2 configuration is suggested for the lower-part of the (ΔI=1) band up to spin Iπ=16+ and the 6-qp π[(g9/2)2(f5/2)1(p1/2)1]⊗ν(g9/2)−2 configuration for the upper-part of the band.