120716454
Evidence of muonium formation using thin gold foils in vacuum
121317828
MEASUREMENT OF POLARIZATION IN K$sup +$p ELASTIC SCATTERING AT 1.37, 1.45, 1.71, AND 1.89 GeV/c AND PHASE-SHIFT ANALYSIS.
122598679
Measurement of the polarization parameter in K$sup +$p elastic scattering
Full angular distributions of the polarization parameter in elastic ${K}^{+}p$ scattering at 1.37, 1.45, 1.60, 1.71, 1.80, 1.89, 2.11, and 2.31 GeV/c are presented. These data were obtained in an experiment at the Zero Gradient Synchrotron using a polarized proton target with arrays of scintillation and \ifmmode \check{C}\else \v{C}\fi{}erenkov counters to detect the scattered particles.
119364085
DOUBLE-HYPERFRAGMENT EVENT PRODUCED BY K$sup -$ INTERACTION AT 2.3 Bev/c IN NUCLEAR EMULSION
An event is shown that consists of two hyperfragments and a meson (K/sup +) coming from a single interaction star found in a nuclear emulsion stack exposed to a meson (K/sup -/) beam at 2.3 and 2.5 Bev/c. Unique identification of the hyperfragments is impossible, but the binding energy favors LAMBDA H/sup 4/ or LAMBDA He/sup 4/. The nature of the production mechanism cannot be determined on the basis of the iniormation available in this single event. (C.E.S.)
122557716
Measurement of the polarization parameter in K+p elastic scattering at 1.60, 1.80, 2.11 and 2.31 GeV/c
Abstract The polarization parameter for K+p elastic scattering has been measured at 1.60, 1.80, 2.11 and 3.31 GeV/c incident momenta over the entire angular range with an emphasis on the backward region. The results in the extreme backward region appear to be small and consistent with zero.
122067625
Quasielastic charmed-baryon production and exclusive strange-particle production by high-energy neutrinos
Three charmed-baryon candidates produced in the quasielastic reaction ..nu..n..--> mu../sup -/..lambda../sub c//sup +/..--> mu../sup -/..lambda pi../sup +/ were found in an exposure of the Fermilab deuterium-filled 15-ft bubble chamber to a wide-band neutrino beam. We also found that the cross section of the associated-production reaction ..nu..n..--> mu../sup -/..lambda..K/sup +/ is (5.5 +- 1.3 +- 1.1) x 10/sup -40/ cm/sup 2/ for E/sub ..nu../>10 GeV, and is approximately independent of energy. In addition we studied the cross sections of some quasi-two-body associated strange-particle production reactions other than ..mu../sup -/..lambda..K/sup +/.
53626095
Recent Heavy Ion Results with the ATLAS Detector at the LHC
Results are presented from the ATLAS collaboration from the 2010 LHC heavy ion run, during which nearly 10 inverse microbarns of luminosity were delivered. Soft physics results include charged particle multiplicities and collective ow. The charged particle multiplicity, which tracks initial state entropy production, increases by more than a factor of two relative to the top RHIC energy, with a centrality dependence very similar to that previously measured at RHIC. Measurements of elliptic ow out to large transverse momentum also show similar results to what was measured at RHIC. Extensions of these measurements to higher harmonics have also been made, and can be used to explain structures in the two-particle correlation functions that had long been attributed to jet-medium interactions. New hard probe measurements include single muons, jets and high pT hadrons. Single muons at high momentum are used to extract the yield of W bosons and are found to be consistent within statistical uncertainties with binary collision scaling. Conversely, jets are found to be suppressed in central events by a factor of two relative to peripheral events, with no signicant dependence on the jet energy. Fragmentation functions are also found to be the same in central and peripheral events. Updated asymmetry results conrm previous measurements with increased statistics, and multiple jet cone sizes are presented. Finally, charged hadron spectra have been measured out to 30 GeV, and their centrality dependence relative to peripheral events is similar to that found for jets.
1646349
Heavy ion physics at the LHC with the ATLAS detector
The ATLAS detector at CERN will provide a high-resolution longitudinally segmented calorimeter and precision tracking for the upcoming study of heavy ion collisions at the LHC ( GeV). The calorimeter covers |η| < 5 with both electromagnetic and hadronic sections, while the inner detector spectrometer covers |η| < 2.5. ATLAS will study a full range of observables necessary to characterize the hot and dense matter formed at the LHC. Global measurements (particle multiplicities, collective flow) will provide access into its thermodynamic and hydrodynamic properties. Measuring complete jets out to 100's of GeV will allow detailed studies of energy loss and its effect on jets. Quarkonia will provide a handle on deconfinement mechanisms. ATLAS will also study the structure of the nucleon and nucleus using forward physics probes and ultraperipheral collisions, both enabled by segmented zero degree calorimeters.
17018955
Landau Hydrodynamics and RHIC Phenomena
The basic physical assumptions and results of Landau's hydrodynamic model of particle production are reviewed. It is argued that these results have sufficient descriptive and predictive power in strong-interaction phenomenology, including recent RHIC data, to warrant a closer examination of the physical assumptions.
14033897
RELATIVISTIC HEAVY ION PHYSICS: RESULTS FROM AGS TO RHIC
High-energy collisions of heavy ions provide a means to study QCD in a regime of high parton density, and may provide insight into its phme structure. Results from the four experiments at RHIC (BRAHMS, PHENIX, PHOBOS and STAR) are presented, and placed in context with the lower energy data from the AGS and SPS accelerators. The focus is on the insights these measurements provide into the time history of the collision process. Taken together, the data point to the creation of a deconfined state of matter that forms quickly, expands rapidly and freezes out suddenly. With the new RHIC data, systematic data now exists for heavy ion collisions as a function of {radical}s over several orders of magnitude and as a function of impact parameter. These data test the interplay between hard and soft processes in a large-volume system where nucleons are struck multiple times. The data is consistent with creating a deconfined state (jet quenching) that forms quickly (saturation models), expands rapidly (radial and elliptic flow) and freezes out suddenly (single freezeout and blast wave fits). There are also intriguing connections with particle production in elementary systems, which point to the role of the energy available for particle production on the features of the final state. Many in this field are optimistic that the careful understanding of this experimental data may lead t o the theoretical breakthroughs that will connect these complex systems to the fundamental lattice predict ions.
118405036
Quantitative and Conceptual Considerations for Extracting the Knudsen Number in Heavy Ion Collisions
In this article, we examine the methodology for extracting the Knudsen number (K) and the ratio of shear viscosity to entropy density ({eta}/s) developed by Drescher et al. [1]. The final result for {eta}/s turns out to be quite sensitive to Glauber parameters, particularly the parameter x, which controls the balance between N{sub part} and N{sub coll}. We also explore how alternative formulations of the functional relation between the elliptic flow and Knudsen number (K={lambda}/R{sup -}) impacts the physics conclusions, based on Pade approximants. Finally, we extend the calculation to include a limiting minimum value on the mean free path proportional to the DeBroglie wavelength. These results emphasize the importance of clarifying the initial state used in different calculations as well as the ambiguities inherent in using a transport approach in a strongly coupled regime.