In the two-neutron-transfer reaction of a 200-MeV O18 beam with a U238 target, deexcitation γ rays in a neutron-rich nucleus of U240 were measured. The γ rays in U240 were identified by taking coincidence with O16, using Si ΔE-E detectors. The kinetic energies of O16 particles allowed us to select the excitation energies of U240 below the neutron separation energy. The ground-state band and the Kπ=0- octupole band of U240 were established up to 12+ and 9-, respectively. The octupole-band head of U240 is about a hundred keV higher than those of U236,238, suggesting that a secondary maximum of octupole correlations exists at N=144-146 in U isotopes.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics