Complete identification of states inPb208belowEx=6.2MeV

Abstract

The Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium of the Ludwig-Maximilians-Universitat Munchen and the Technische Universitat Munchen (Garching, Germany), was used to study the Pb-208(p, p'), Pb-206,Pb-207,Pb-208(d, p), and Pb-208(d, d') reactions. One hundred fifty-one states at E-x < 6.20MeV in Pb-208 are identified and spin and parity assigned. Four states are newly identified and new spins and/or parities are assigned to 25 states. Tentative spin assignments are done to five states at 5.90 < E-x < 6.10 MeV. Nearly 50 levels below E-x = 6.20MeV listed by the Nuclear Data Sheets as of 2007 are recognized to be nonexistent or doubly placed. The schematic shell model describing one-particle-one-hole configurations without residual interaction is extended by including two-particle-two-hole configurations. The number of configurations thus predicted at E-x < 6.20MeV nearly agrees with the number of states identified. Several states with dominant two-particle-two-hole configurations are identified. New isobaric analog resonances in Bi-209 with two-particle-one-hole structure are discovered at E-res = 17.6MeV. The excitation energies of 70 states with unnatural parity at E-x < 6.20 MeV are found to agree within about 200 keV with one-particle-one-hole configurations predicted by the extended schematic shell model. In contrast, the excitation energies of about 20 natural parity states are more than 0.5 MeV lower than predicted, demonstrating the residual interaction among the configurations to be much larger for natural parity than for unnatural parity.