DIRECT PROTON DECAY FROM THE GAMOW-TELLER RESONANCE IN BI-208

Spin-isospin excitations in Bi-208 have been investigated using the Pb -208(He-3,t)Bi-208 reaction at and near theta approximate to 0 degrees at E(He-3)=450 MeV. The microscopic structure of the Gamow-Teller res onance (GTR), the isobaric analog state (IAS), and the spin-flip dipol e (Delta L = 1) resonance (SDR) in Bi-208 has been studied by observin g their direct proton decays to the low-lying neutron-hole states in P b-207. Decay protons were measured at backward angles in coincidence w ith tritons detected at and near 0 degrees. The total branching ratio for proton decay from the GTR is determined to be only 4.9+/-1.3%. The total branching ratio for proton decay from the SDR amounts to 14.1+/ -4.2%. The deduced total widths as well as the total and partial proto n escape widths of the GTR and IAS are found to be in reasonable agree ment with recent theoretical estimates obtained in the framework of th e continuum Tamm-Dancoff approximation.