A large acceptance experiment at the CERN Super Proton Synchrotron to study elastic and other 2-body hadronic interactions up to 100 GeV/c

An experiment at the CERN Super Proton Synchrotron to measure elastic scattering between hadrons is described. The equipment, the trigger logic and the data analysis are described in some detail. The data have so far been obtained at 20 GeV/c, 30 GeV/c and 50 GeV/c primary beam momentum. The acceptance of the apparatus covers the c.m. scattering angular range from about 100 to about 1000. The results, which are preliminary, are presented with some accompanying comments. The Constituent Interchange Model is compared to the results at the wider angles in the c.m. system. The model disagrees with the results. However, the scaling law which follows from dimensional considerations assuming that quark dynamics are the fundamental interactions, is consistent with the results in the large c.m. scattering angle region. The antiproton-proton elastic scattering cross section has been measured in the region 1(GeV/c)2 <=-t<=3.5(GeV/c)2 at 50 GeV/c. A dip is observed at -t approx.=1.4(GeV/c)2. The differential cross section coincides with the pp elastic differential cross section at 1500 GeV/c. (Auth.)