The reaction: A means to study the microscopic structure of spin-isospin modes

The microscopic structure of both the Gamow-Teller resonance (GTR) at Eχ = 15.6 MeV and the spin-flip ΔL=1 resonances at higher excitation energies in 208Bi has been investigated by observing their direct proton decay to the 3p12, 2f52, 3p32, 1i32 and 2f72 neutron-hole states in 207Pb, following their excitation via the 208Pb (3He,t) reaction at E(3He) = 450 MeV. Decay protons were measured at backward angles in coincidence with tritons detected at very forward angles including θ = 0°. The total widths of the resonances as well as total and partial proton escape widths were determined and compared to theoretical estimates for the GTR. Using the same experimental set-up and conditions proton decay of the spin-flip ΔL=1 resonances in 12C was also measured.