The use of quasielastic pion-proton backward scattering at 0.7 GeV/c for studying fermi motion in light nuclei

The plane-wave approximation was used to examine the proton Fermi-momentum distribution in experiments on quasielastic large-momentum-transfer pion-nu cleon scattering in light nuclei Li-6, Li-7, and C-12. It was found that, u nlike the (e, e') reaction, the Fermi-gas model is in poor agreement with e xperiment, whereas the oscillator model adequately describes the spectrum s hape. However, the parameters obtained for these distributions are sizably smaller than those derived from the (e, e') experiments. This suggests that the plane-wave approach is inadequate and that more complicated theoretica l approaches, supposedly allowing for pion-nucleon amplitude modification i n nuclear matter, are necessary for the analysis of experimental data. (C) 2000 MAIK "Nauka/Interperiodica".