Two-quasiparticle K-isomers and pairing strengths in the neutron-rich isotopes Er-174 and Er-172

Isomeric two-quasi particle states have been identified in the neutron-rich isotopes Er-172 and Er-174 using multi-nucleon transfer reactions with Xe-136 beams incident on various targets, and gamma-ray spectroscopy with Gammasphere. A candidate for the K-pi = 6(+) two-quasi neutron state in 172Er is found at 1500 keV In Er-174, a nuclide whose level scheme was previously unknown, a long-lived isomer is identified at 1112 keV decaying via an inhibited E1 transition and revealing the yrast sequence of Er-174. This isomer is proposed to be a K-pi = 8(-) two-quasi neutron state, defining a sequence in the N = 106 isotones extending from the well-deformed neutron-rich isotope Er-174 to the neutron-deficient isotope Pb-188, where the presence of the isomer signifies a prolate minimum in an otherwise spherical well. Configuration-constrained potential-energy surface calculations are used to predict the excitation energies of the 6(+) and 8(-) intrinsic states and as a basis for extracting the pairing force strength, G(n), in the N = 104 and N = 106 isotones. (c) 2006 Elsevier B.V. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000236630600004&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, MultidisciplinarySCI(E)30ARTICLE4200-20663