Two-phonon octupole excitation in 146Gd

Based on experimental evidence from the 144 Sm(α,2n) reaction, the 3484.7-keV 6 + state in 146 Gd is identified as the highest-spin member of the 3- ⊗ 3 - two-phonon octupole quartet. A previously unknown y line of 1905.8 keV and E3 character feeding the 3- octupole state has been observed. These results represent the first observation of a 6 + → 3- → 0 + cascade of two E3 transitions in an even-even nucleus and provide strong support for the interpretation of the 6 + state as a two-phonon octupole excitation.