Elastic scattering of. pi. sup + and. pi. sup minus from sup 4 He between 90 and 240 MeV

In a series of experiments, differential cross sections for elastic scattering of {pi}{sup +} and {pi}{sup {minus}} from {sup 4}He were measured at the Clinton P. Anderson Meson Physics Facility (LAMPF). Data were taken at incident energies between {ital T}{sub {pi}}=90 and 240 MeV using different experimental setups which covered the angular range from far forward ({approx}10{degree}) to far backward angles ({approx}170{degree}). A phase-shift analysis of the data was carried out. The experimental phase shifts are compared with values predicted by a first-order optical model program.