124960626
Beam characterization with video imaging systems at the ANL 50 MeV H/sup -/ beamline
Video imaging systems consisting of scintillators, charge-coupled device (CCD) cameras, and in-beam CCD detectors are being used to characterize beams at the Argonne National Laboratory (ANL) 50 MeV H/sup -/ beamline. The characterization technique consists of placing pinholes, slits, or wires in the beam and viewing the resulting images or shadows on a downstream scintillator or CCD. The images are digitally recorded using a frame grabber and stored in computer memory where they are analyzed to determine Twiss parameters and local beam divergence. Since many of the measurements involve low-intensity beams and require good position resolution, studies have been performed on scintillators to obtain sensitivity and resolution data. Various scintillators, including Rarex, CsI, and CaF/sub 2/, have been evaluated. An in-beam CCD imager has also been tested.<<ETX>>
22020112
Operating Experience with the Resonance Extraction Slow Spill Control System at the Zero Gradient Synchrotron
Simultaneous resonance extraction to two proton lines became operational in spring of 1975. The spill quality was initially poor due to 100% structure in the two to six kHz range. This paper describes the empirical techniques developed to provide a smooth spill. These techniques consist of applying radial or azimuthal disturbances to the proton beam. It has been found that the most effective disturbing frequency depends uniquely on the beam momentum. Quite an array of new equipment had to be built for magnetic control of the unbunched beam. Brief descriptions of this equipment are provided.
119436928
Center vortices and the asymptotic string tension
Abstract We present a method for locating center vortices (“fluxons”) in thermalized lattice gauge field configurations. We find evidence, in lattice Monte Carlo simulations, that the asymptotic string tension of fundamental-representation Wilson loops is due to fluctuations in the number of center vortices linking those loops.
121645626
Plasma signatures from chiral condensates around quark multiplets
Abstract We study the structure of the QCD vacuum by analyzing the chiral condensate around static quark multiplets. We find a suppression of the chiral condensate around quark multiplet sources relative to the vacuum which decreases with higher sea quark mass and increases with higher multiplicity of the sources. Across the deconfinement phase transition the suppression becomes less pronounced. The behavior of different multiplets seems to fit into a screening law with Casimir scaling. The suppression of meson production as a consequence of the restoration of chiral symmetry is discussed.