Band structures extending to very high spin in Xe126

High-spin states in Xe-126 have been populated in the Se-82(Ca-48,4n)Xe-126 reaction in two experiments, one at the VIVITRON accelerator in Strasbourg using the Euroball detector array, and a subsequent one with ATLAS at Argonne using the Gammasphere Ge-detector array. Levels and assignments made previously for Xe-126 up to I=20 have been confirmed and extended. Four regular bands extending to a spin of almost I=60, which are interpreted as two pairs of signature partners with opposite parity, are identified for the first time. The alpha = 0 partner of each pair is connected to the lower-lying levels, whereas the two alpha = 1 partners remain floating. A fractional Doppler shift analysis of transitions in the strongest populated (pi,alpha)=(-,0) band provides a value of 5.2(0.5)(0.4) b for the transition quadrupole moment, which can be related to a minimum in the potential-energy surface calculated by the ULTIMATE CRANKER cranked shell-model code at epsilon approximate to 0.35 and gamma approximate to 5 degrees. The four lowest bands calculated for this minimum compare well with the two signature pairs experimentally observed over a wide spin range. A sharp upbend at h omega similar to 1170 keV is interpreted as a crossing with a band involving the j(15/2) neutron orbital, for which pairing correlations are expected to be totally quenched. The four long bands extend to within similar to 5 spin units of a crossing with an yrast line defined by calculated hyperdeformed transitions and will serve as important stepping stones into the spin region beyond 60h for future experiments.