Pion- and proton-nucleus interactions at intermediate energy

Abstract

We report on scattering and reaction experiments on light nuclei using the [pi]-meson and proton beams from the Los Alamos Meson Physics Facility (LAMPF) and the Indiana University Cyclotron Facility (IUCF). Differential cross sections, cross section asymmetries, and angular correlation functions have been measured in order to test models of the reaction mechanism and of nuclear structure. At LAMPF we have measured asymmetries for pion scattering from polarized [sup 13]C which are uniquely sensitive to the isoscalar spin density. In order to determine details of the reaction mechanism, we have obtained approval for a scattering experiment on polarized [sup 3]He for which the nuclear structure is very well known. We have completed data taking for two studies of elastic scattering of [pi][sup +] from [sup 6]Li and [sup l3]C. The detailed differential cross sections from these experiments will be used to constrain theoretical analyses of previous polarization experiments done at the Pierre-Scherrer-Institute (PSI) and at LAMPF. We have analyzed [pi]-triton coincidence events from the [sup 4]He([pi],[pi][prime] t)p reaction and have found evidence for direct triton knockout from [sup 4]He. We have extended these angular correlation measurements to higher energies and to [sup 2]H and [sup 3]He targets. At IUCF we have performed the first [sup 4]He(p,n) experiment at intermediate energies, T[sub p] = 100, 147, and 200 MeV, in a search for previously reported narrow states in [sup 4]Li of widths of [approx] 1 MeV. Within the statistics of the data we have found no evidence for such narrow structures.