Highly deformed band structures due to core excitations in $^{123}$Xe

High-spin states in Xe-123 were populated in the Se-80(Ca-48, 5n) Xe-123 reaction at a beam energy of 207 MeV. gamma-ray coincidence events were recorded with the Gammasphere spectrometer. Four new high-spin bands have been discovered in this nucleus. The bands are compared with those calculated within the framework of cranked Nilsson-Strutinsky and cranked Nilsson-Strutinsky-Bogoliubov models. It is concluded that the configurations of the bands involve two-proton excitations across the Z = 50 as well as excitation of neutrons across the N = 82 shell gaps resulting in a large deformation, epsilon(2) approximate to 0.30 and gamma approximate to 5 degrees.