ANALOG RESONANCES OF TL-206 AND TL-204

The levels of Tl206 and Tl204 are studied by observing their analog resonances in the reactions Tl205,203(p,p0) and Tl205,203(p,p′). The lowest-lying states formed by a proton hole (3s12) coupled to a neutron hole (3p12, 2f52, or 3p32) are observed to resonate weakly as in the case of the neutron-hole states formed in the Pb206(p,p0) analog resonances. Above 2.5-MeV excitation energy in the parent nucleus, states containing neutron particles coupled to the target ground-state core are observed to resonate strongly. The energy spreads of the dominant configurations [(3s12-1)p(nlj)n]Jπ are deduced by comparing the total widths measured in the inelastic channels to the total widths measured in the decay of the (nlj)n configuration formed in the Pb208(p,p′) reaction. The g92 neutron strength remains highly localized in both Tl206 and Tl204, which have total widths (Γ) of 219 and 217 keV, respectively, compared with the Pb209 width of 253 keV. In the energy region of the 2g72-3d32 neutron stength, Γ=427996 keV for Tl206 and Tl204, respectively, compared to Γ=300 keV for Pb209. The strengths of these configurations are thus spread over an energy range 150 keV in Tl206, 700 keV in Tl204, whereas the two states are split by 50 keV in Pb209. © 1969 The American Physical Society.