THE (HE-3,T(P)OVER-BAR) REACTION - A MEANS TO STUDY THE MICROSCOPIC STRUCTURE OF SPIN-ISOSPIN MODES

The microscopic structure of both the Gamow-Teller resonance (GTR) at E(x) = 15.6 MeV and the spin-flip Delta L=1 resonances at higher excitation energies in Bi-208 has been investigated by observing their direct proton decay to the 3(p1/2,) 2f(5/2,) 3(p3/2,) 1i(13/2) and 2f(7/2) neutron-hole states in Pb-207, following their excitation via the (208)pb(He-3,t) reaction at E(3He) = 450 MeV. Decay protons were measured at backward angles in coincidence with tritons detected at very forward angles including theta = 0 degrees. 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 Delta L=1 resonances in C-12 was also measured.