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ENGINEERING OF THE AGS SNAKE COIL ASSEMBLY. (open access)

ENGINEERING OF THE AGS SNAKE COIL ASSEMBLY.

A 30% Snake superconducting magnet is proposed to maintain polarization in the AGS proton beam, the magnetic design of which is described elsewhere. The required helical coils for this magnet push the limits of the technology developed for the RHIC Snake coils. First, fields must be provided with differing pitch along the length of the magnet. To accomplish this, a new 3-D CAD system (''Pro/Engineer'' from PTC), which uses parametric techniques to enable fast iterations, has been employed. Revised magnetic field calculations are then based on the output of the mechanical model. Changes are made in turn to the model on the basis of those field calculations. To ensure that accuracy is maintained, the final solid model is imported directly into the CNC machine programming software, rather than by the use of graphics translating software. Next, due to the large coil size and magnetic field, there was concern whether the structure could contain the coil forces. A finite element analysis was performed, using the 3-D model, to ensure that the stresses and deflections were acceptable. Finally, a method was developed using ultrasonic energy to improve conductor placement during coil winding, in an effort to minimize electrical shorts due to conductor …
Date: May 12, 2003
Creator: ANERELLA,M. GUPTA,R. KOVACH,P. MARONE,A. PLATE,S. POWER,K. SCHMALZLE,J. WILLEN,E.
System: The UNT Digital Library
DETERMINING THE RATIO OF THE H+ YIELDS TV TO H+ YIELDS TB DECAY RATES FOR LARGE TAN BETA AT THE LARGE HADRON COLLIDER. (open access)

DETERMINING THE RATIO OF THE H+ YIELDS TV TO H+ YIELDS TB DECAY RATES FOR LARGE TAN BETA AT THE LARGE HADRON COLLIDER.

We present results on the determination of the observable ratio R = BR(H{sup +} {yields} {tau}{sup +}{nu}{sup -})/BR(H{sup +} {yields} t{bar b}) of charged Higgs boson decay rates as a discriminant quantity between Supersymmetric and non-Supersymmetric models. Simulation of measurements of this quantity through the analysis of the charged Higgs production process gb {yields} tbH{sup +} and relative backgrounds in the two above decay channels has been performed in the context of ATLAS. A {approx} 12-14% accuracy on R can be achieved for tan {beta} = 50, m{sub H{sup {+-}}} = 300-500 GeV and after an integrated luminosity of 300 fb{sup -1}. With this precision measurement, the Large Hadron Collider (LHC) can easily discriminate between models for the two above scenarios, so long as tan {beta} > 20.
Date: May 27, 2003
Creator: ASSAMAGAN,K. A. GUASCH,J. MORETTI,S. PENARANDA,S.
System: The UNT Digital Library
Charged Higgs bosons in the transition region M{sub H{sup {+-}}} {approx} m{sub t} at the LHC (open access)

Charged Higgs bosons in the transition region M{sub H{sup {+-}}} {approx} m{sub t} at the LHC

We illustrate preliminary results obtained through Monte Carlo (HERWIG) and detector (ATLFAST) simulations of the H{sup {+-}} {yields} {tau}{sup {+-}}{nu}{sub {tau}} signature of charged Higgs bosons with masses comparable to that of the top quark.
Date: May 25, 2003
Creator: ASSAMAGAN,K. A. GUCHAIT,M. MORETTI,S.
System: The UNT Digital Library
Heavy-Duty Emissions Control: Plasma-Facilitated vs Reformer-Assisted Lean NOx Catalysis (open access)

Heavy-Duty Emissions Control: Plasma-Facilitated vs Reformer-Assisted Lean NOx Catalysis

Progress has been made in the control of combustion processes to limit the formation of environmentally harmful species, but lean burn vehicles, such as those powered by diesel engines used for the majority of commercial trucking and off-road applications, remain a major source of nitrogen oxides (NOx) and particulate matter (PM) emissions. Tighter control of the combustion process coupled with exhaust gas recirculation has brought emissions in line with 2004 targets worldwide. Additional modifications to the engine control system, somewhat limited NOx control, and PM filters will likely allow the 2007 limits to be met for the on-highway regulations for heavy-duty engines in the United States. Concern arises when the NOx emission limit of 0.2 g/bhphr set for the year 2010 is considered.
Date: August 24, 2003
Creator: Aardahl, C. L.; Rozmiarek, R. T.; Rappe, K. G.; Mendoza, D. P. & Park, P. W.
System: The UNT Digital Library
A Fusion Chamber for the 2002 Robust Point Design (open access)

A Fusion Chamber for the 2002 Robust Point Design

A top-level overview of the mechanical design for the 2002 Robust Point Design (RPD-2002) fusion chamber is introduced. It is based on the HYLIFE-II design and includes modifications to the liquid pocket configuration and first structural wall (FSW), facilitates periodic maintenance or replacement of internal components, and is compliant with all other RPD-2002 parameters. This work has been carried out by constructing a parametric computer model capable of being updated as future changes become necessary.
Date: October 1, 2003
Creator: Abbott, R P
System: The UNT Digital Library
Simulation Data as Data Streams (open access)

Simulation Data as Data Streams

Computational or scientific simulations are increasingly being applied to solve a variety of scientific problems. Domains such as astrophysics, engineering, chemistry, biology, and environmental studies are benefiting from this important capability. Simulations, however, produce enormous amounts of data that need to be analyzed and understood. In this overview paper, we describe scientific simulation data, its characteristics, and the way scientists generate and use the data. We then compare and contrast simulation data to data streams. Finally, we describe our approach to analyzing simulation data, present the AQSim (Ad-hoc Queries for Simulation data) system, and discuss some of the challenges that result from handling this kind of data.
Date: November 19, 2003
Creator: Abdulla, G.; Arrighi, W. & Critchlow, T.
System: The UNT Digital Library
Partition of solutes into wet and dry ethers; an LFER analysis (open access)

Partition of solutes into wet and dry ethers; an LFER analysis

Article on the partition of solutes into wet and dry ethers and an LFER analysis.
Date: June 10, 2003
Creator: Abraham, M. H. (Michael H.) & Acree, William E. (William Eugene)
System: The UNT Digital Library
Some Novel Liquid Partitioning Systems: Water-Ionic Liquids and Aqueous Biphasic Systems (open access)

Some Novel Liquid Partitioning Systems: Water-Ionic Liquids and Aqueous Biphasic Systems

Article on water-ionic liquids and aqueous biphasic systems and some novel liquid partitioning systems.
Date: January 11, 2003
Creator: Abraham, M. H. (Michael H.); Zissimos, Andreas M.; Huddleston, Jonathan G.; Willauer, Heather D.; Rogers, Robin D. & Acree, William E. (William Eugene)
System: The UNT Digital Library
Evolution of Electronic Properties of (Cu(In,Ga)Se2 (CIGS)-Based Solar Cells During a 3-Stage Growth Process: Preprint (open access)

Evolution of Electronic Properties of (Cu(In,Ga)Se2 (CIGS)-Based Solar Cells During a 3-Stage Growth Process: Preprint

We investigated the electronic properties of ZnO/CdS/CIGS /Mo/SLG polycrystalline thin-film solar cells with compositions ranging from Cu-rich to In(Ga)-rich by deep-level transient spectroscopy (DLTS) and capacitance-voltage (C-V) measurements. This compositional change represents the evolution of the film during growth by the 3-stage process. Two sets (four samples each) of CIGS thin films were prepared with Ga/(In+Ga) ratios of~0.3 (low Ga) and~0.6 (high Ga). The Cu/(In+Ga) ratio ranges from 1.24 (Cu-rich) to 0.88 (In(Ga)-rich). The films were treated with NaCN to remove the Cu2-xSe phase where needed. Key results include: (1) For low-Ga devices, DLTS data show that acceptor-like traps dominate in samples where CIGS grains do not go through the Cu-rich to In(Ga)-rich transition, whereas donor-like traps dominate in In(Ga)-rich samples. Therefore, we see a clear transformation of defects from acceptor-like to donor-like traps. The activation energies of these traps range from 0.12 to 0.63 eV. We also observed that NaCN treatment eliminates a deep minority trap in the In(Ga)-rich devices, (2) For high-Ga devices, only majority-carrier traps were detected. These traps again range from shallow to deep, (3) The carrier concentration around the junction and the density of traps decrease as the CIGS becomes more In(Ga)-rich.
Date: April 1, 2003
Creator: AbuShama, J. A.; Johnston, S.; Ahrenkiel, R.; Crandall, R.; Young, D. & Noufi, R.
System: The UNT Digital Library
Heterogeneidad estructural y lumínica del sotobosque de una selva nublada andina de Venezuela (open access)

Heterogeneidad estructural y lumínica del sotobosque de una selva nublada andina de Venezuela

Article discussing the understory of an Andean cloud forest in the Sierra Nevada National Park, Venezuela.
Date: July 2003
Creator: Acevedo, Miguel F.; Ataroff, Michele; Monteleone, Susan & Estrada, Carlos A.
System: The UNT Digital Library
Fuel and Additive Characterization for HCCI Combustion (open access)

Fuel and Additive Characterization for HCCI Combustion

This paper shows a numerical evaluation of fuels and additives for HCCl combustion. First, a long list of candidate HCCl fuels is selected. For all the fuels in the list, operating conditions (compression ratio, equivalence ratio and intake temperature) are determined that result in optimum performance under typical operation for a heavy-duty engine. Fuels are also characterized by presenting Log(p)-Log(T) maps for multiple fuels under HCCl conditions. Log(p)-Log(T) maps illustrate important processes during HCCl engine operation, including compression, low temperature heat release and ignition. Log(p)-Log(T) diagrams can be used for visualizing these processes and can be used as a tool for detailed analysis of HCCl combustion. The paper also includes a ranking of many potential additives. Experiments and analyses have indicated that small amounts (a few parts per million) of secondary fuels (additives) may considerably affect HCCl combustion and may play a significant role in controlling HCCl combustion. Additives are ranked according to their capability to advance HCCl ignition. The best additives are listed and an explanation of their effect on HCCl combustion is included.
Date: February 12, 2003
Creator: Aceves, S. M.; Flowers, D.; Martinez-Frias, J.; Espinosa-Loza, F.; Pitz, W. J. & Dibble, R.
System: The UNT Digital Library
U-Th/He age of phenocrystic garnet from the 79AD eruption of Mt. Vesuvius (open access)

U-Th/He age of phenocrystic garnet from the 79AD eruption of Mt. Vesuvius

None
Date: November 3, 2003
Creator: Aciego, Sarah; Kennedy, B. M.; DePaolo, Donald J.; Christensen, John N. & Hutcheon, Ian
System: The UNT Digital Library
Effects of Nonlinear Absorption in BK7 and Color Glasses at 355 nm (open access)

Effects of Nonlinear Absorption in BK7 and Color Glasses at 355 nm

We have demonstrated a simple experimental technique that can be used to measure the nonlinear absorption coefficients in glasses. We determine BK7, UG1, and UG11 glasses to have linear absorption coefficients of 0.0217 {+-} 10% cm{sup -1}, 1.7 {+-} 10% cm{sup -1}, and 0.82 {+-} 10% cm{sup -1}, respectively, two-photon absorption cross-sections of 0.025 {+-} 20% cm/GW, 0.035 {+-} 20% cm/GW, and 0.047 {+-} 20% cm/GW, respectively, excited-state absorption cross-sections of 8.0 x 10{sup -18} {+-} 20% cm{sup 2}, 2.8 x 10{sup -16} {+-} 20% cm{sup 2}, and 5 x 10{sup -17} {+-} 20% cm{sup 2}, respectively, and solarization coefficients of 8.5 x 10{sup -20} {+-} 20% cm{sup 2}, 2.5 x 10{sup -18} {+-} 20% cm{sup 2}, and 1.3 x 10{sup -19} {+-} 20% cm{sup 2}, respectively. For our application, nonlinear effects in 10-cm of BK7 are small ({le} 2%) for 355-nm fluences < 0.2 J/cm{sup 2} for flat-top pulses. However, nonlinear effects are noticeable for 355-nm fluences at 0.8 J/cm{sup 2}. In particular, we determine a 20% increase in the instantaneous absorption from linear, a solarization rate of 4% per 100 shots, and a 10% temporal droop introduced in the pulse, for 355-nm flat-top pulses at a fluence of …
Date: November 12, 2003
Creator: Adams, J. J.; McCarville, T.; Bruere, J.; McElroy, J. & Peterson, J.
System: The UNT Digital Library
Azimuthal anisotropy at RHIC: The first and fourth harmonics (open access)

Azimuthal anisotropy at RHIC: The first and fourth harmonics

No abstract prepared.
Date: October 28, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Azimuthally sensitive HBT in Au+Au collisions at sqrt(snn) = 200 GeV (open access)

Azimuthally sensitive HBT in Au+Au collisions at sqrt(snn) = 200 GeV

No abstract prepared.
Date: December 8, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Cross sections and transverse single-spin asymmetries in forward neutral pion production from proton collisions at sqrt(s) = 200 GeV (open access)

Cross sections and transverse single-spin asymmetries in forward neutral pion production from proton collisions at sqrt(s) = 200 GeV

No abstract prepared.
Date: October 29, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Event-by-event hexb pt hexb fluctuations in Au-Au collisions atsqrt(sNN) = 130 GeV (open access)

Event-by-event hexb pt hexb fluctuations in Au-Au collisions atsqrt(sNN) = 130 GeV

We present the first large-acceptance measurement of event-wise <p{sub t}> fluctuations in Au-Au collisions at {radical}s{sub NN} = 130 GeV. Significant nonstatistical fluctuations are observed. The measured fractional r.m.s. width excess of the event-wise <p{sub t}> distribution for the 15% most-central events for charged hadrons within |{eta}| < 1 and 0.15 {le} p{sub t} {le} 2 GeV/c is 13.7 {+-} 0.1(stat) {+-}1.3(syst)% relative to a statistical reference. The variation of charge-independent fluctuation excess with centrality is non-monotonic but smooth. Charge-dependent nonstatistical fluctuations are also observed.
Date: September 2, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Identified particle distributions in pp and Au+Au collisions atsqrt sNN=200 GeV (open access)

Identified particle distributions in pp and Au+Au collisions atsqrt sNN=200 GeV

Transverse mass and rapidity distributions for charged pions, charged kaons, protons and antiprotons are reported for {radical}sNN = 200 GeV pp and Au+Au collisions at RHIC. The transverse mass distributions are rapidity independent within |y| < 0.5, consistent with a boost-invariant system in this rapidity interval. Spectral shapes and relative particle yields are similar in pp and peripheral Au+Au collisions and change smoothly to central Au+Au collisions. No centrality dependence was observed in the kaon and antiproton production rates relative to the pion production rate from medium-central to central collisions. Chemical and kinetic equilibrium model fits to our data reveal strong radial flow and relatively long duration from chemical to kinetic freeze-out in central Au+Au collisions. The chemical freeze-out temperature appears to be independent of initial conditions at RHIC energies.
Date: October 6, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Multi-strange baryon production in Au+Au collisions at {radical}s{sub NN} = 130 GeV (open access)

Multi-strange baryon production in Au+Au collisions at {radical}s{sub NN} = 130 GeV

The transverse mass spectra and mid-rapidity yields for {Xi}s and {Omega}s plus their anti-particles are presented. The 10% most central collision yields suggest that the amount of multi-strange particles produced per produced charged hadron increases from SPS to RHIC energies. A hydrodynamically inspired model fit to the spectra, which assumes a thermalized source, seems to indicate that these multi-strange particles experience a significant transverse flow effect, but are emitted when the system is hotter and the flow is smaller than values obtained from a combined fit to {pi}, K, p and {lambda}s.
Date: July 30, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Multi-strange baryon production in Au-Au collisions at sqrt(sNN) = 130 GeV (open access)

Multi-strange baryon production in Au-Au collisions at sqrt(sNN) = 130 GeV

The transverse mass spectra and mid-rapidity yields for {Xi}s and {Omega}s plus their anti-particles are presented. The 10% most central collision yields suggest that the amount of multi-strange particles produced per produced charged hadron increases from SPS to RHIC energies. A hydrodynamically inspired model fit to the spectra, which assumes a thermalized source, seems to indicate that these multi-strange particles experience a significant transverse flow effect, but are emitted when the system is hotter and the flow is smaller than values obtained from a combined fit to {pi}, K, p and {Lambda}s.
Date: July 31, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Particle-type dependence of azimuthal anisotropy and nuclearmodification of particle production in Au+Au collisions at sNN = 200GeV (open access)

Particle-type dependence of azimuthal anisotropy and nuclearmodification of particle production in Au+Au collisions at sNN = 200GeV

We present STAR measurements of the azimuthal anisotropy parameter v{sub 2} and the binary-collision scaled centrality ratio R{sub CP} for kaons and lambdas ({Lambda} + {bar {Lambda}}) at mid-rapidity in Au+Au collisions at {radical}s{sub NN} = 200 GeV. In combination, the v{sub 2} and R{sub CP} particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish p{sub T} {approx} 5 GeV/c as the value where the centrality dependent baryon enhancement ends. The K{sub S}{sup 0} and {Lambda} + {bar {Lambda}} v{sub 2} values are consistent with expectations of constituent-quark-number scaling from models of hadron formation by parton coalescence or recombination.
Date: June 18, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Pion-Kaon correlations in central Au+Au collisions at {radical}(s{sub NN}) = 130 GeV (open access)

Pion-Kaon correlations in central Au+Au collisions at {radical}(s{sub NN}) = 130 GeV

No abstract prepared.
Date: July 31, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at sqrt(sNN) = 200 GeV (open access)

Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at sqrt(sNN) = 200 GeV

Identified mid-rapidity particle spectra of {pi}{sup {+-}}, K{sup {+-}}, and p({bar p}) from 200 GeV p+p and d+Au collisions are reported. A time-of-flight detector based on multi-gap resistive plate chamber technology is used for particle identification. The particle-species dependence of the Cronin effect is observed to be significantly smaller than that at lower energies. The ratio of the nuclear modification factor (R{sub dAu}) between (p+ {bar p}) and charged hadrons (h) in the transverse momentum range 1.2 < p{sub T} < 3.0 GeV/c is measured to be 1.19 {+-} 0.05(stat) {+-} 0.03(syst) in minimum-bias collisions and shows little centrality dependence. The yield ratio of (p + {bar p})/h in minimum-bias d+Au collisions is found to be a factor of 2 lower than that in Au+Au collisions, indicating that the Cronin effect alone is not enough to account for the relative baryon enhancement observed in heavy ion collisions at RHIC.
Date: September 16, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library
Rapidity and centrality dependence of proton and anti-proton production from 197Au+197Au collisions at {radical}(s{sub NN}) = 130 GeV (open access)

Rapidity and centrality dependence of proton and anti-proton production from 197Au+197Au collisions at {radical}(s{sub NN}) = 130 GeV

We report on the rapidity and centrality dependence of proton and anti-proton transverse mass distributions from {sup 197}Au + {sup 197}Au collisions at {radical}s{sub NN} = 130 GeV as measured by the STAR experiment at RHIC. Our results are from the rapidity and transverse momentum range of |y| < 0.5 and 0.35 < p{sub t} < 1.00 GeV/c. For both protons and anti-protons, transverse mass distributions become more convex from peripheral to central collisions demonstrating characteristics of collective expansion. The measured rapidity distributions and the mean transverse momenta versus rapidity are flat within |y| < 0.5. Comparisons of our data with results from model calculations indicate that in order to obtain a consistent picture of the proton(anti-proton) yields and transverse mass distributions the possibility of pre-hadronic collective expansion may have to be taken into account.
Date: June 20, 2003
Creator: Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
System: The UNT Digital Library