Investigation of 0+states in mercury isotopes after two-neutron transfer

Abstract

Using the high-resolution Q3D magnetic spectrograph at the Maier-Leibnitz Laboratory (MLL) Tandem accelerator in Munich, we studied 0+ excitations in the mercury isotopes 198 Hg, 200 Hg, and 202 Hg after two-neutron transfer. We only observed 4-6 excited 0+ states per nucleus up to about 3-MeV excitation energy, far fewer than in other experiments of this (p, t ) campaign. The results reveal a sharp drop in the number of low-lying 0+ states towards the 208 Pb shell closure. We discuss the low-energy 0+ state density as a function of the valence nucleon number N val . The 0+ excitation energies and the measured (p, t ) transfer cross sections indicate a structural change throughout the Hg isotopes, with the most notable result being the peaking in the cross section of the low-lying excited 02 + state in 200 Hg.