Thomson scattering in the corona of laser-produced gold plasmas (open access)

Thomson scattering in the corona of laser-produced gold plasmas

Thomson scattering measurements of the electron temperature in laser- produced gold plasmas are presented. We irradiated a flat gold disk target with one laser beam of the Nova laser facility. A second laser beam probed the plasma at a distance of 500{mu}m with temporally resolved Thomson scattering. The electron temperature measurements are compared with hydrodynamic simulations using the code LASNEX for experiments applying smoothed and unsmoothed heater beams. In case of an unsmoothed heater beam the simulations predict temperatures which are about 40% higher than our measured data. Although the agreement is improved for a smoothed heater beam, discrepancies exist in the decay phase of the plasma. We discuss possible explanations for these observations.
Date: May 8, 1996
Creator: Glenzer, S. H.; Back, C. A.; Estabrook, K. G. & MacGowan, B. J.
System: The UNT Digital Library
Gist: A scientific graphics package for Python (open access)

Gist: A scientific graphics package for Python

{open_quotes}Gist{close_quotes} is a scientific graphics library written by David H. Munro of Lawrence Livermore National Laboratory (LLNL). It features support for three common graphics output devices: X Windows, (Color) PostScript, and ANSI/ISO Standard Computer Graphics Metafiles (CGM). The library is small (written directly to Xlib), portable, efficient, and full-featured. It produces X versus Y plots with {open_quotes}good{close_quotes} tick marks and tick labels, 2-dimensional quadrilateral mesh plots with contours, vector fields, or pseudo color maps on such meshes, with 3-dimensional plots on the way. The Python Gist module utilizes the new {open_quotes}Numeric{close_quotes} module due to J. Hugunin and others. It is therefore fast and able to handle large datasets. The Gist module includes an X Windows event dispatcher which can be dynamically added (e.g., via importing a dynamically loaded module) to the Python interpreter after a simple two-line modification to the Python core. This makes fast mouse-controlled zoom, pan, and other graphic operations available to the researcher while maintaining the usual Python command-line interface. Munro`s Gist library is already freely available. The Python Gist module is currently under review and is also expected to qualify for unlimited release.
Date: May 8, 1996
Creator: Busby, L.E.
System: The UNT Digital Library
The heavy top quark and supersymmetry (open access)

The heavy top quark and supersymmetry

Three aspects of supersymmetric theories are discussed: electroweak symmetry breaking, the issues of flavor, and gauge unification. The heavy top quark plays an important, sometimes dominant, role in each case. Additional symmetries lead to extensions of the standard model which can provide an understanding for many of the outstanding problems of particle physics. A broken supersymmetric extension of spacetime allows electroweak symmetry breaking to follow from the dynamics of the heavy top quark; an extension of isospin provides a constrained framework for understanding the pattern of quark and lepton masses; and a grand unified extension of the standard model gauge group provides an elegant understanding of the gauge quantum numbers of the components of a generation. Experimental signatures for each of these additional symmetries are discussed.
Date: May 8, 1996
Creator: Hall, L.J.
System: The UNT Digital Library