HIGH PERPENDICULAR CHARGED PARTICLES AZIMUTHAL CORRELATION IN PHENIX. (open access)

HIGH PERPENDICULAR CHARGED PARTICLES AZIMUTHAL CORRELATION IN PHENIX.

A two-particle azimuthal correlation analysis of the PHENIX data taken at {radical}s{sub NN} = 130 GeV/c is discussed. A comparison of the magnitude of v{sub 2}(p{perpendicular}) extracted from the correlation analysis with those obtained from a reaction plane analysis by the STAR collaboration, indicate surprisingly small non-flow contributions. A similar comparison obtained from the CERES experiment at {radical}s{sub NN} = 17 GeV/c shows stronger non-flow contributions for a similar p{perpendicular}-range which can be attributed to the presence of mini-jets. It is argued that for the p{perpendicular}-range below 2-3 GeV/c the RHIC results may be indicative of a novel particle production mechanism related to low-x gluon saturation.
Date: January 13, 2002
Creator: RAK,J. FOR THE PHENIX COLLABORATION
System: The UNT Digital Library
SCALING PROPERTIES OF THE TRANSVERSE MASS SPECTRA. (open access)

SCALING PROPERTIES OF THE TRANSVERSE MASS SPECTRA.

Motivated from the formation of an initial state of gluon-saturated matter, we discuss scaling relations for the transverse mass spectra at BNL's Relativistic Heavy-Ion Collider (RHIC). We show on linear plots, that the transverse mass spectra for various hadrons can be described by an universal function in m{sub t}. The transverse mass spectra for different centralities can be rescaled into each other. Finally, we demonstrate that m{sub t}-scaling is also present in proton-antiproton collider data and compare it to m{sub t}-scaling at RHIC.
Date: January 13, 2002
Creator: Schaffner-Bielich, J.; Kharzeev, D.; Mclerran, L. & Venugopalan, R.
System: The UNT Digital Library
VERTICAL MIXING AND CHEMISTRY OVER AN ARID URBAN SITE: FIRST RESULTS FROM AIRCRAFT OBSERVATIONS MADE DURING THE PHOENIX SUNRISE CAMPAIGN. (open access)

VERTICAL MIXING AND CHEMISTRY OVER AN ARID URBAN SITE: FIRST RESULTS FROM AIRCRAFT OBSERVATIONS MADE DURING THE PHOENIX SUNRISE CAMPAIGN.

The role of boundary layer mixing is increasingly recognized as an important factor in determining the concentrations of ozone and other trace gases near the surface. While the concentrations at the surface can vary widely due to horizontal transport of chemical plumes, the boundary layer is also characterized by turbulence that follows a diurnal cycle in height and intensity. Surface oxidant concentrations can therefore undergo significant changes even in the absence of photochemistry. A central goal of the Phoenix 2001 Field Campaign was to study vertical mixing with the onset of convection and to quantify the effect of this mixing on chemistry within an urban boundary layer. As part of this study, a series of low altitude aircraft sampling flights were made over the Greater Phoenix area between June 16-30, 2001. The resulting observations, in conjunction with a series of surface measurements and meteorological observations, are being used to study the vertical transport and reactivity of ozone and ozone-precursors shortly after sunrise. Additional details of this campaign are given in Doran, et al. (2002). It was anticipated that turbulence over Phoenix at night would be suppressed as a result of cooling of the boundary layer over the city. By sampling …
Date: January 13, 2002
Creator: Berkowitz, C. M.; Springston, S. R.; Doran, J. C. & Fast, J. D.
System: The UNT Digital Library
Fast Wavefront Reconstruction in Large Adaptive Optics Systems Using the Fourier Transform (open access)

Fast Wavefront Reconstruction in Large Adaptive Optics Systems Using the Fourier Transform

Wavefront Reconstruction using the Fast Fourier Transform and spatial filtering is shown to be computationally tractable and sufficiently accurate for use in large Shack Hartmann-based adaptive optics systems (up to at least 10,000 actuators). This method is significantly faster and can have lower noise propagation than traditional VMM reconstructors. The boundary problem which prevented the accurate reconstruction of phase in circular apertures using square-grid FTs is identified and solved. The methods are adapted for use on the Fried-geometry. Detailed performance analysis of mean squared error and noise propagation for FT methods is presented, using both theory and simulation.
Date: January 13, 2002
Creator: Poyneer, L; Gravel, D T & Brase, J M
System: The UNT Digital Library