The Gluon Spin Asymmetry as a Link to Delta G and Orbital Angular Momentum

The fundamental program in high energy spin physics focuses on the spin structure of the nucleon. The gluon and orbital angular momentum components of the nucleon spin are virtually unknown. The J_z=1/2 sum rule involves the integrated parton densities and can be used to extract information on the orbital angular momentum and its evolution. To avoid any bias on a model of Delta G, we assume that the gluon asymmetry, A=Delta G/G can be used to extract Delta G over a reasonable kinematic region. Combining the results for Delta G with the evolution equations, we can determine a theoretical expression for the orbital angular momentum and its evolution.Comment: 4 pages, LaTeX2e, 1 figure. Talk given at SPIN2004, Trieste, Ital

A Comparison of Spin Observable Predictions for RHIC

There have been many versions of spin-dependent parton distributions in the literature. Although most agree with present data within uncertainties, they are based upon different physical assumptions. Some physical models are discussed and the corresponding predictions for double spin asymmetries are shown. A summary of the most feasible measurements in the appropriate kinematic regions at RHIC, which should yield the most useful information about the polarized gluon distribution, is given.Comment: 7 pages, 3 Postscript figures. To be published in the proceedings of the Circum-Pan-Pacific RIKEN Workshop on High Energy Spin Physics, RIKEN, Waco, Japan, November 3-6, 199

Determining Spin-Flavor Dependent Distributions

Many of the present and planned polarization experiments are focusing on determination of the polarized glue. There is a comparable set of spin experiments which can help to extract information on the separate flavor-dependent polarized distributions. This talk will discuss possible sets of experiments, some of which are planned at BNL, CERN, DESY and JHF, which can be used to determine these distributions. Comments will include the estimated degree to which these distributions can be accurately found.Comment: 6 pages, LaTeX, uses aipproc.sty. Talk given at SPIN 2002, Brookhaven National Laboratory, September 9-13, 200

Polarized Parton Distributions and the Polarized Gluon Asymmetry

The flavor-dependent valence, sea quark and antiquark spin distributions can be determined separately from theoretical assumptions and experimental data. We have determined the valence distributions using the Bjorken sum rule and have extracted polarized sea distributions, assuming that the quarks and anti-quarks for each flavor are symmetric. Other experiments have been proposed which will allow us to completely break the SU(3) symmetry of the sea flavors. To create a physical model for the polarized gluons, we investigate the gluon spin asymmetry in a proton, $A_G(x,Q^2)={{\Delta G(x,Q^2)}\over {G(x,Q^2)}}$. By assuming that htis is is approximately $Q^2$ invariant, we can completely determine the $x$-dependence of this asymmetry, which satisfies constituent counting rules and reproduces the basic results of the Bremsstrahlung model originated by Close and Sivers. This asymmetry can be combined with the measured unpolarized gluon density, $G(x,Q^2)$ to provide a prediction for $\Delta G(x,Q^2)$. Existing and proposed experiments can test both the prediction of scale-invariance for $A_G(x,Q^2)$ and the nature of $\Delta G$ itself. These models will be discussed along with suggestions for specific experiments which can be performed at energies typical of HERA, RHIC and LHC to determine these polarized distributions.Comment: 8 pages, LaTeX, 1 figure. Talk given at the 3rd Circum-Pan-Pacific Symposium on High Energy Spin Physics, Beijing, China, October, 200

Experimental Procedure for the Determination of the Number of Paramagnetic Centers

The determination of the number of paramagnetic centers in a given crystal is usually performed by comparing the resonance signal of the unknown centers with that of a calibrated standard. The two most often used standards are CuSO4·5H2O and DPPH. In the procedure described below the number of "spins" is obtained from a measurement of the reflection coefficient of a reflection cavity containing the spins; or more specifically from the change in the reflection coefficient between the "on resonance" and "off resonance" conditions. The measurements can be performed with the aid of the conventional equipment for the measurement of reflection coefficients. Great simplification is realized when a variable coupling cavity [1] is used

OpenPING: A Reflective Middleware for the Construction of Adaptive Networked Game Applications

The emergence of distributed Virtual Reality (VR) applications that run over the Internet has presented networked game application designers with new challenges. In an environment where the public internet streams multimedia data and is constantly under pressure to deliver over widely heterogeneous user-platforms, there has been a growing need that distributed VR applications be aware of and adapt to frequent variations in their context of execution. In this paper, we argue that in contrast to research efforts targeted at improvement of scalability, persistence and responsiveness capabilities, much less attempts have been aimed at addressing the flexibility, maintainability and extensibility requirements in contemporary distributed VR platforms. We propose the use of structural reflection as an approach that not only addresses these requirements but also offers added value in the form of providing a framework for scalability, persistence and responsiveness that is itself flexible, maintainable and extensible. We also present an adaptive middleware platform implementation called OpenPING1 that supports our proposal in addressing these requirements