High-spin structure of 121Xe: Triaxiality, band termination and signature inversion

Abstract

High-spin states of the odd-neutron 121Xe nucleus have been studied with Eurogam using the 96Zr(30Si, 5n)121Xe fusion-evaporation reaction. The level scheme has been extended up to a tentative spin of 67/2h at an excitation energy of ~14 MeV. Several new rotational bands have been observed and the previously known bands extended. Two of them lose their regular character at high spins, which may be interpreted as transition from collective behaviour to a regime of noncollective oblate states. The deduced high-spin structure is compared to Woods-Saxon TRS cranking and CSM calculations. Configurations of the bands have been suggested. The vh11/2 band is interpreted as having a triaxial shape. Signature inversion and an unexpectedly large staggering of the B(M1)/B(E2) ratios has been found for one of the bands. Enhanced E1 transitions have been observed between the vd5/2 and the vh11/2 bands.