Nuclear response in theFe54(p→,p→’) reaction at 290 MeV

Cross sections, analyzing powers and spin-flip probabilities have been measured for inclusive inelastic scattering of 290 MeV protons from ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ at laboratory angles between 3.1° and 20°. The momentum transfers vary from small values (q∼0.2 ${\mathrm{fm}}^{\mathrm{-}1}$) where individual giant resonances of low multipolarity are observed, to larger values (q∼1.4 ${\mathrm{fm}}^{\mathrm{-}1}$) where quasielastic scattering dominates. Complete measurements of spin observables at 20° are discussed, which show that present impulse approximation models based on either the Dirac or the Schrödinger equation for the nucleon are not capable of reproducing all the data. At all momentum and energy transfers the measured analyzing powers ${\mathit{A}}_{\mathit{y}}$ are smaller than predictions from nonrelativistic calculations. Relativistic calculations explain this reduction of ${\mathit{A}}_{\mathit{y}}$ for data near the quasielastic point (ω=${\mathit{q}}^2$/2m) as an effect of the attractive scalar field in the nuclear medium; however, they fail to reproduce the observed slopes [d(${\mathit{A}}_{\mathit{y}}$)/dω at fixed angle], assuming for the nuclear response a simple Fermi gas model.