Antiproton - He-4 Interactions At 200 Mev/c

The differential cross sections for antiproton elastic scattering on He-4 at 192.8 MeV/c are measured. The annihilation cross section sigma(a) = (377.6+/-8.0) mb, the elastic cross section sigma(el) = (206.3+/-6.6) mb and the total pBARHe-4 interaction cross section sigma(tot) = (583.9+/-10.4) mb are determined. The ratio of the real to imaginary part of the forward pBARHe-4 amplitude is found: rho = -0.17(-0.33)+0.24. Partial wave analysis reveals that the S, P and D waves are essential in this energy region.