Measurements using 200 MeV protons of the spin-flip probability parameter ${\mathrm{S}}_{\mathrm{NN}\prime }$ have been made on ${\mathrm{Pb}}^{208}$ covering an excitation energy range of 2 to 24 MeV for momentum transfers from 0.45 to 0.84 ${\mathrm{fm}}^{-1\mathrm{}}$. These data have been compared to calculations that use random-phase-approximation wave functions in an impulse approximation model. Distortions are shown to have a large effect in the calculation of ${\mathrm{S}}_{\mathrm{NN}\prime }$. The calculations describe the data well and suggest that natural-parity transitions contribute significantly to the spin-flip response. A broad structure is observed near 7 MeV; calculations suggest that this structure is composed of a superposition of a number of spins and parities.

• Received 26 April 1991

DOI:https://doi.org/10.1103/PhysRevC.44.R1233