In-beam {gamma}-ray spectroscopy of {sup 240}U using the ({sup 18}O,{sup 16}O) reaction

In the two-neutron-transfer reaction of a 200-MeV {sup 18}O beam with a {sup 238}U target, deexcitation {gamma} rays in a neutron-rich nucleus of {sup 240}U were measured. The {gamma} rays in {sup 240}U were identified by taking coincidence with {sup 16}O, using Si {delta}E-E detectors. The kinetic energies of {sup 16}O particles allowed us to select the excitation energies of {sup 240}U below the neutron separation energy. The ground-state band and the K{sup {pi}}=0{sup -} octupole band of {sup 240}U were established up to 12{sup +} and 9{sup -}, respectively. The octupole-band head of {sup 240}U is about a hundred keV higher than those of {sup 236,238}U, suggesting that a secondary maximum of octupole correlations exists at N=144-146 in U isotopes.