Indications of octupole correlation in 84Sr

Abstract

Excited states in the 84Sr nucleus were investigated via the 76Ge(12C,4n)84Sr reaction at a beam energy of 58 MeV. The de-excited γ-rays were detected using the Indian National Gamma Array (INGA) spectrometer at Inter-University Accelerator Center, New Delhi. Directional Correlation from Oriented (DCO) states ratio and the polarization asymmetry (Δ) measurements were done to confirm the spin-parity of the low-lying states. Eight new γ-ray transitions were placed in the level scheme of 84Sr. The systematic behaviour of energy staggering S(I) of the γ-band (Band 1 and Band 2) was compared with the γ-bands in the mass A ≈ 80 region and the nuclei of other mass regions with similar behaviour (odd-I down). The E1 character is confirmed for strong γ-ray transitions connecting Band 3 to the Yrast band. Comparison of new results such as B(E1)/B(E2) ratio, frequency ratio ω −/ω + and energy displacement ΔE in 84Sr with those of 72Se, 150Sm, 152Gd, 220Ra and 224Th nuclei suggests the presence of octupole correlations in 84Sr.