EPJ Web of Conferences 123, 02001 (2016)
https://doi.org/10.1051/epjconf/201612302001

A dipole band above the I^π= 31/2⁻ isomeric state in ¹⁸⁹Pb

School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom

^a e-mail: dave.cullen@manchester.ac.uk

Published online: 5 September 2016

Abstract

This contribution focuses on the new observation of a dipole band built upon an I^π=31/2⁻ isomeric state in ¹⁸⁹Pb, identified using recoil-isomer tagging at the University of Jyväskylä, Finland. This is the lightest odd-mass Pb isotope in which a dipole band is known. By comparison with the heavier-mass dipole bands, the dipole band in ¹⁸⁹Pb was deduced to be based upon a $$\pi {\left(s_{1/2}^{-2}{h}_{9/2}{i}_{13/2}\right)}_{{11}^{-}}\otimes v{\left(i_{13/2}^{-1}\right)}_{13/2^{+}}$$ configuration. However, in the ¹⁸⁹Pb dipole band, the initial aligned angular momentum was larger than that exhibited by the dipole bands in the heavier-mass isotopes. This may be evidence for a reduced repulsive proton/neutron-hole interaction in ¹⁸⁹Pb.