Spin-parity assignments and extension of the 0₂⁺ band in ¹⁵⁸Er

¹ Department of Physics and Astronomy, University of the Western Cape, P/B X17, Bellville, ZA - 7535 South Africa
² iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West, South Africa
³ University of Johannesburg, Department of Physics, P.O. Box 524, Auckland Park 2006, South Africa
⁴ Department of Physics, University of Stellenbosch, Private Bag X1, 7602 Matieland, South Africa
⁵ Department of Physics, University of Cape Town, Private Bag, 7701 Rondebosch, South Africa

^a e-mail: tdinoko@tlabs.ac.za

Published online: 19 December 2013

Abstract

Low and medium spin collective structures in ¹⁵⁸Er have been studied using the ¹⁵⁰Sm(¹²C,4nγγ) fusion-evaporation reaction at a beam energy of E_lab = 65 MeV. A band built on the 0₂⁺ excitation has been established and extended to J^π = 18⁺ from the analysis of γ-γ coincidence relationships, intensity arguments and DCO ratios. The 0₂⁺ band in ¹⁵⁸Er presents a similar trend to the 0₂⁺ bands in the lighter N = 90 isotones but lies about 125 keV higher. This systematic trend supports a similar configuration for the 0₂⁺ bands in the N = 90 isotones.