Nuclear Experiment·nucl-ex
5 papers—2 primary·3 cross-listed·reconstructed*
An outlook on physics at the high energy frontier of nucleus-nucleus collisions is presented, on the basis of the new results presented at Quark Matter 2011 by the LHC and RHIC experiments.
Holger Eberhardt (for the CBELSA/TAPS collaboration)🇩🇪
Near threshold omega meson photoproduction is studied with the CBELSA/TAPS experiment at the ELSA accelerator of Bonn University. Single as well as double polarization observables are measured using either linear or circular polarized photon beams and a longitudinal polarized proton target.
Yu.N. Uzikov🇷🇺 · J. Haidenbauer🇩🇪 · B.A. Prmantaeva🇰🇿
Antiproton scattering off and targets is considered at beam energies below 300 MeV within the Glauber-Sitenko approach, utilizing the amplitudes of the Jülich model as input. A good agreement with available data on differential cross sections and on and reaction cross sections is obtained. Predictions for polarized total He cross sections are presented, calculated within the single-scattering approximation and including Coulomb-nuclear interference effects. The kinetics of the polarization buildup is discussed.
Lei Chang🇺🇸 · Craig D. Roberts🇺🇸 · Peter C. Tandy🇺🇸
We provide a brief review of recent progress in the study of mesons using QCD's Dyson-Schwinger equations. Along the way we touch on aspects of confinement and dynamical chiral symmetry breaking but in the main focus upon: exact results for pseudoscalar mesons, including aspects of the eta-eta' problem; a realisation that the so-called vacuum condensates are actually an intrinsic, localised property of hadrons; an essentially nonperturbative procedure for constructing a symmetry-preserving Bethe-Salpeter kernel, which has enabled a demonstration that dressed-quarks possess momentum-dependent anomalous chromo- and electromagnetic moments that are large at infrared momenta, and resolution of a longstanding problem in understanding the mass-splitting between rho- and a1-mesons such that they are now readily seen to be parity partners in the meson spectrum; features of electromagnetic form factors connected with charged and neutral pions; and computation and explanation of valence-quark distribution functions in pseudoscalar mesons. We argue that in solving QCD, a constructive feedback between theory and extant and forthcoming experiments will enable constraints to be placed on the infrared behaviour of QCD's beta-function, the nonperturbative quantity at the core of hadron physics.
T. Brunner🇨🇦 · A.R. Mueller · K. O'Sullivan🇺🇸 · M.C. Simon🇨🇦 · M. Kossick · S. Ettenauer🇨🇦 · A.T. Gallant🇨🇦 · E. Mané🇨🇦 · D. Bishop · M. Good🇨🇦 · G. Gratta🇺🇸 · J. Dilling🇨🇦
Bradbury Nielsen gates are well known devices used to switch ion beams and are typically applied in mass or mobility spectrometers for separating beam constituents by their different flight or drift times. A Bradbury Nielsen gate consists of two interleaved sets of electrodes. If two voltages of the same amplitude but opposite polarity are applied the gate is closed, and for identical (zero) potential the gate is open. Whereas former realizations of the device employ actual wires resulting in difficulties with winding, fixing and tensioning them, our approach is to use two grids photo-etched from a metallic foil. This design allows for simplified construction of gates covering large beam sizes up to at least 900\,mm with variable wire spacing down to 250\,\textmu m. By changing the grids the wire spacing can be varied easily. A gate of this design was installed and systematically tested at TRIUMF's ion trap facility, TITAN, for use with radioactive beams to separate ions with different mass-to-charge ratios by their time-of-flight.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.