Elementary particle physics: Experimental

A research program was performed in high energy experimental particle physics. Studies of high energy hadronic interactions and leptoproduction processes continue using several experimental techniques. Progress was made on the study of multiparticle production processes in nuclei. Ultra-high energy cosmic ray nucleus-nucleus interactions were investigated by the Japanese American Cosmic Emulsion Experiment (JACEE) using balloon-borne emulsion chamber detectors. In the area of particle astrophysics, studies of cosmic ray nuclear interactions made possible the use of the world's most accurate determination of the comparison of the cosmic rays above 10(exp 13)eV. It is the only detector that can observe interaction vertices and identify particles at energies up to 10 to 15 eV. The observations are getting close to placing limits on the acceleration mechanisms postulated for pulsars in which the spin and magnetic moment axes are at different angles. In June, 1989 approval was given by NASA for our participation in the Space Station program. The SCINATT experiment will make use of emulsion chamber detectors, similar to the planned JACEE hybrid balloon flight detectors. These detector will permit precise determination of secondary particle charges, momenta and rapidities, and the accumulation of data will be at least a factor of 10 to 100 greater than in balloon experiments. Emulsion chamber techniques are also employed in an experiment using accelerator heavy ion beams at CERN and Brookhaven National Laboratory to investigate particle production processes in central collisions of nuclei in the energy range 15 to 200A GeV. The study of hadroproduction in lepton interactions is continuing with approval of another 8 months run for deep inelastic muon scattering experiment E665 at Fermilab.