Robust test of E(5) symmetry in {sup 128}Xe.

Low-lying collectively excited states of {sup 128}Xe were investigated by {gamma}-ray spectroscopy following the {sup 12}C({sup 128}Xe,{sup 128}Xe*){sup 12}C projectile Coulomb excitation reaction. Nineteen absolute E2 transition strengths were obtained including the first measurement of the critical B(E2) decays from the second and third J{sup TT} = 0{sup +} states. These data are compared with the theoretical predictions of the critical point symmetry E(5) and allow us to conclude that {sup 128}Xe is not an E(5) nucleus as previously suggested, leaving {sup 130}Xe as the most likely candidate among the Xe isotopes.