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First experiments with the Plastic Ball

Description: After two and a half years of development and construction, an electronic 4..pi.. detector has been used for the first time in studying relativistic nuclear collisions. This detector complements the visual 4..pi.. detectors like emulsions, AgCl detectors, and the streamer chamber, which have been in use for many years. Only the streamer chamber has the same important feature as the Plastic Ball in being triggerable for specific event types. In a series of experiments with beams of /sup 20/Ne, /sup 40/Ar, and /sup 40/Ca up to energies of 1.05 GeV/u, approximately three million events were measured with various trigger conditions. In contrast to the visual detectors, these events are already totally digitized and ready for immediate analysis. All multiparticle correlations of charged particles are measured in each event and do not have to be determined as an average quantity from two particle inclusive data. Besides the particle identification of the hydrogen and helium isotopes, the Plastic Ball identifies the positive pions. This makes it interesting for the study of pion production, which sets in at around 100 MeV/u incident energy, and has promise to shed some light onto the equation of state of nuclear matter. Besides the analysis of the data in the standard way of selections and of single particle inclusive data, a global analysis is in progress that should allow us to determine the reaction plane, and the event shape in phase space. The operation and general layout of the Plastic Ball are described. (WHK)
Date: March 1, 1982
Creator: Gutbrod, H.H.; Baden, A. & Loehner, H.
Partner: UNT Libraries Government Documents Department

Higgs hunting

Description: The phenomenology of the Higgs boson in the standard SU(2) x U(1) electroweak model is reviewed. We compare signatures and cross sections for various Higgs production mechanisms: (1) toponium radiative decay (xi ..-->.. H/sup 0/..gamma..); (2) gluon gluon fusion (gg ..-->.. H/sup 0/); (3) Compton-like process (gc ..-->.. H/sup 0/c); and (4) bremsstrahlungs at Z/sup 0/ resonance. It is argued that new detection techniques for heavy particle identification could be helpful in triggering the rare Higgs signals from the backgrounds.
Date: January 1, 1982
Creator: Keung, W.Y.
Partner: UNT Libraries Government Documents Department

4. pi. physics with the plastic ball

Description: 4 ..pi.. data taken with the Plastic Ball show that cluster production in relativistic nuclear collisions depends on both the size of the participant volume and the finite size of the cluster. The measurement of the degree of thermalization and the search for collective flow will permit the study of the applicability of macroscopic concepts such as temperature and density.
Date: October 1, 1982
Creator: Gutbrod, H.H.; Loehner, H.; Poskanzer, A.M.; Renner, T.; Riedesel, H.; Ritter, H.G. et al.
Partner: UNT Libraries Government Documents Department

High-resolution spectrometer at PEP

Description: A description is presented of the High Resolution Spectrometer experiment (PEP-12) now running at PEP. The advanced capabilities of the detector are demonstrated with first physics results expected in the coming months.
Date: January 1, 1982
Creator: Weiss, J.M. & Collaboration, HRS
Partner: UNT Libraries Government Documents Department

Study of /sup 12/C interactions at HISS

Description: Single-particle inclusive measurements in high-energy nuclear physics have provided the foundation for a number of models of interacting nuclear fluids. Such measurements yield information on the endpoints of the evolution of highly excited nuclear systems. However, they suffer from the fact that observed particles can be formed in a large number of very different evolutionary paths. To learn more about how interactions proceed we have performed a series of experiments in which all fast nuclear fragments are analyzed for each individual interaction. These experiments were performed at the LBL Bevalac HISS (Heavy Ion Spectrometer System) facility where we studied the interaction of 1 GeV/nuc 12C nuclei with targets of C, CH/sub 2/, Cu, and U. In this paper we describe HISS and present some preliminary results of the experiment.
Date: December 1, 1982
Creator: Crawford, H.J.
Partner: UNT Libraries Government Documents Department

High-luminosity considerations

Description: There appears to be some controversy over how high a luminosity one can use before a variety of detector limitations impose a practical limit. Factors leading to flux limitations for a variety of detector types are discussed, and practical considerations to extending those limits are reviewed. Also, a method of reducing the effects of pileup inherent in calorimeter use at L = 10/sup 33//cm/sup 2//sec is given.
Date: January 1, 1982
Creator: Platner, E.D.
Partner: UNT Libraries Government Documents Department