CORE EXCITATIONS ACROSS THE NEUTRON SHELL GAP IN Tl-207

Deep-inelastic collisions of a 208Pb beam on a 208Pb target were performed using the ATLAS accelerator at Argonne National Laboratory. Prompt and delayed γ-rays from the reaction products were detected using the GAMMASPHERE detector array. The cross-coincidence method was used to identify transitions in 207Tl, by gating on γ-rays from its better-characterised reaction partner 209Bi. A number of new transitions were found in 207Tl

STRUCTURE OF Pb-207 POPULATED IN Pb-208+Pb-208 DEEP-INELASTIC COLLISIONS

The yrast structure of 207Pb above the 13=2+ isomeric state has been investigated in deep-inelastic collisions of 208Pb and 208Pb at ATLAS, Argonne National Laboratory. New and previously observed transitions were measured using the Gammasphere detector array. The level scheme of 207Pb is presented up to ∼ 6 MeV, built using coincidence and γ-ray intensity analyses. Spin and parity assignments of states were made, based on angular distributions and comparisons to shell model calculations

Core excitations across the neutron shell gap in Tl-207

The single closed-neutron-shell, one proton-hole nucleus 207Tl was populated in deep-inelastic collisions of a 208Pb beam with a 208Pb target. The yrast and near-yrast level scheme has been established up to high excitation energy, comprising an octupole phonon state and a large number of core excited states. Based on shell-model calculations, all observed single core excitations were established to arise from the breaking of the N=126 neutron core. While the shell-model calculations correctly predict the ordering of these states, their energies are compressed at high spins. It is concluded that this compression is an intrinsic feature of shell-model calculations using two-body matrix elements developed for the description of two-body states, and that multiple core excitations need to be considered in order to accurately calculate the energy spacings of the predominantly three-quasiparticle states

STRUCTURE OF Pb-207 POPULATED IN Pb-208+Pb-208 DEEP-INELASTIC COLLISIONS

The yrast structure of 207Pb above the 13=2+ isomeric state has been investigated in deep-inelastic collisions of 208Pb and 208Pb at ATLAS, Argonne National Laboratory. New and previously observed transitions were measured using the Gammasphere detector array. The level scheme of 207Pb is presented up to ∼ 6 MeV, built using coincidence and γ-ray intensity analyses. Spin and parity assignments of states were made, based on angular distributions and comparisons to shell model calculations