Neutron-particle and proton-hole excitations in the N=128 isotones 208 Hg and 209 Tl from spectroscopy following 208 Pb+ 238 U deep-inelastic reactions

Gamma rays in the π−2ν2 nucleus 208Hg and π−1ν2 nucleus 209Tl have been studied at Gammasphere using deep-inelastic reactions induced by a 1360 MeV208 Pb beam on a thick 238U target. Previously unknown yrast γ-ray cascades above the 8+ and 17/2+ nanosecond isomers in 208Hg and 209Tl, respectively, were identified in coincidence with known γ rays deexciting the isomers. Yrast levels up to spin 13− in 208Hg have been located, and they are interpreted in light of the structure of the 210Pb isotone and with the help of shell model calculations. Shell model calculations by using the Vlow–k realistic interaction have been performed for 210Pb and 208Hg, and compared with experiment. The Vlow–k effective Hamiltonian seems to account well for the properties of these neutron-rich shell model nuclei.