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[en] Continued effort was directed to the study of multiparticle production processes in nuclei. In the earlier phases of this contract, protons were used as the projectile; within the last two years we have begun to investigate cascades produced by projectiles having quite different mean-free-paths in nuclear matter. In the past year, three papers were published summarizing results on multiparticle production on nuclei using hadron and lepton beams. A new experiment was performed at Fermilab to search for new particles produced by neutrino interactions in nucelar emulsion targets located inside the 15' bubble chamber. In this hybrid experiment, the deuterium filled bubble chamber provides a rough location for the interaction vertex, and identifies and momentum analyzes the produced particles while the emulsion provides a close look at the event vertex. The experiment is a collaborative effort involving U.S., Polish and Soviet groups. Russian-made cryogenically sensitized emulsions will be used. As a result of participation in the hybrid emulsion-bubble chamber experiment as well as the earlier muon, pion and proton experiments, at disposal is a unique opportunity to compare and contrast leptoproduction and hadroproduction. Also continued is an analysis of nucleus-nucleus interactions from LBL heavy ion beams. A list of publications is included

[en] Experimental research in high energy physics is summarized. A list of publications is included

[en] Progress was made on a research program directed to the study of multiparticle production in heavy nuclei by 200 to 400 GeV protons and mesons at the Fermi National Accelerator Laboratory. The work was directed to the study of the development of the intranuclear cascading processes in nuclei having atomic mass numbers as large as A = 184. The experimental results have been compared with the current theories, energy-flux-cascade model, two-phase model, coherent-production model and thermodynamic-hydrodynamical model. While each theory provides a satisfactory explanation of a portion of the experimental results, considerably more work is required to understand the development of multiparticle cascades in large nuclei. Work is in progress to investigate the type of particles produced in deep inelastic interactions of 150 GeV muons. A new technique was introduced in this experiment that made it possible to locate very rare modes of interactions in a nuclear emulsion target. The desired high resolution required nuclear emulsions as a target but the rarity of deep-inelastic events, approximately equal to 1/1000, prohibited the use of ordinary scanning methods. The new feature of this experiment was the use of counter systems to predict the location of the interaction. Scanning time was then reduced to a small portion of the experiment. Work on the examination of the deep inelastic interactions started in February and the particles emitted in the interactions are being measured. Information is being sought on the production of particles of the type predicted by theory (charm, etc.) as well as any other ''new'' type of short-lived particles

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[en] A research program to investigate several aspects of the hadronic interaction process at very high energies through nuclear emulsion techniques continues. An experiment at Fermilab searched for new particle production by neutrino interactions in nuclear emulsion targets inside the 15' bubble chamber. In this hybrid experiment, the deuterium-filled bubble chamber provided a rough location for the interaction vertex, and identified and momentum-analyzed the produced particles, while the emulsion provided a close look at the event vertex. A second exposure is planned for late 1980. Continued effort was directed to the study of multiparticle production processes in nuclei. In the earlier phases of this contract, protons and pions were used as the projectile; within the last few years, leptoproduction and nucleus-nucleus interactions have been investigated. There is, of course, considerable theoretical interest in this topic, since the development of intranuclear cascades, their multiplicities, and rapidity distributions are strongly dependent on the nature of the first interaction of the incident particle

[en] We are continuing a research program in high energy experimental particle physics and particle astrophysics. Studies of high energy hadronic interactions were performed using several techniques, in addition, a high energy leptoproduction experiment was continued at the Fermi National Accelerator Laboratory. We are participants in a joint US/Japan program to study nuclear interactions at energies two orders of magnitude greater than those of existing accelerators. The data are being collected with ballon-borne emulsion chambers. The properties of nuclear interactions at these high energies will reveal whether new production mechanisms come into play due to the high nuclear densities and temperatures obtained. We carried out closely related studies of hadronic interactions in emulsions exposed to high energy accelerator beams. We are members of a large international collaboration which has exposed emulsion chamber detectors to beams of ³²S and ¹⁶O with energy 60 and 200 GeV/n at CERN and 15 GeV/n at Brookhaven National Laboratory. The primary objectives of this program are to determine the existence and properties of the hypothesized quark-gluon phase of matter, and its possible relation to a variety of anomalous observations. Studies of leptoproduction processes at high energies involve two separate experiments, one using the Tevatron 500 GeV muon beam and the other exploring the >TeV regime. We are participants in Fermilab experiment E665 employing a comprehensive counter/streamer chamber detector system. During the past year we joined the DUMAND Collaboration, and have been assigned responsibility for development and construction of critical components for the deep undersea neutrino detector facility, to be deployed in 1991. In addition, we are making significant contributions to the design of the triggering system to be used

[en] We are carrying out a research program in high energy experimental particle physics. Studies of high energy hadronic interactions and leptoproduction processes continue using several experimental techniques. Progress has been made on the study of multiparticle production processes in nuclei. Ultra-high energy cosmic ray nucleus-nucleus interactions have been investigated by the Japanese American Cosmic Emulsion Experiment (JACEE) using balloon-borne emulsion chamber detectors. In the area of particle astrophysics, our studies of cosmic ray nuclear interactions have enabled use to make the world's most accurate determination of the comparison of the cosmic rays above 10¹³eV. We have only the detector that can observe interaction vertices and identify particles at energies up to 10**15 eV. Our 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 ate 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 -- 200A GeV. Our study of hadroproduction in lepton interactions is continuing with approval of another 8 months run for deep inelastic muon scattering experiment E665 at Fermilab

[en] We are continuing a research program in particle astrophysics and high energy experimental particle physics. We have joined the DUMAND Collaboration, which is constructing a deep undersea astrophysical neutrino detector near Hawaii. Studies of high energy hadronic interactions using emulsion chamber techniques were also continued, using balloon flight exposures to ultra-high cosmic ray nuclei (JACEE) and accelerator beams. As members of the DUMAND Collaboration, we have responsibility for development a construction of critical components for the deep undersea neutrino detector facility. We have designed and developed the acoustical positioning system required to permit reconstruction of muon tracks with sufficient precision to meet the astrophysical goals of the experiment. In addition, we are making significant contributions to the design of the database and triggering system to be used. Work has been continuing in other aspects of the study of multiparticle production processes in nuclei. We are participants in a joint US/Japan program to study nuclear interactions at energies two orders of magnitude greater than those of existing accelerators, using balloon-borne emulsion chambers. On one of the flights we found two nuclear interactions of multiplicity over 1000 -- one with a multiplicity of over 2000 and pseudorapidity density ∼ 800 in the central region. At the statistical level of the JACEE experiment, the frequency of occurrence of such events is orders of magnitude too large. We have continued our ongoing program to study hadronic interactions in emulsions exposed to high energy accelerator beams