2-PHONON GAMMA-VIBRATIONAL STATES IN ER-166

The nucleus Er-166 has been Coulomb excited using a beam of Ni-58. In addition to the ground- and gamma-vibrational bands three states were observed, a new state at 1943 keV, a previously known 4(+) state at 19 78 keV and a new state at 2029 keV suggested to have also spin and par ity 4(+). The two 4(+) states decay to the 2(+) and 3(+) states of the one-phonon gamma-vibrational band, and their B(E2) values to the 2(ga mma)(+) state are measured to 490(-25)(+20) and 267(-100)(+100) e(2) f m(4), respectively. It is suggested that the 1978 keV state has a smal l and the 2029 keV state a large component of the K-pi=4(+) two-phonon gamma vibrational configuration in their wave functions.