We have measured in-beam γ rays in the neutron-rich 246Pu152 and 245Pu151 nuclei by means of Pu244(O18, O16)Pu246 and Pu244(O18, O17)Pu245 neutron transfer reactions, respectively. The γ rays emitted from Pu246 (Pu245) were identified by selecting the kinetic energy of scattered O16 (O17) detected by Si ΔE-E detectors. The ground-state band of Pu246 was established up to the 12+ state. We have found that the shell gap of N=152 is reduced in energy with decreasing atomic number by extending the systematics of the one-quasiparticle energies in N=151 nuclei into those in Pu245. This reduction of the shell gap clearly affects the 2+ energy of the ground-state band of Pu246.
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