Pseudorapidity Asymmetry and Centrality Dependence of Charged Hadron Spectra in d+Au collisions at sqrt(sNN) = 200 GeV (open access)

Pseudorapidity Asymmetry and Centrality Dependence of Charged Hadron Spectra in d+Au collisions at sqrt(sNN) = 200 GeV

The pseudorapidity asymmetry and centrality dependence of charged hadron spectra in d+Au collisions at {radical}s{sub NN} = 200 GeV are presented. The charged particle density at mid-rapidity, its pseudorapidity asymmetry and centrality dependence are reasonably reproduced by a Multi-Phase Transport model, by HIJING, and by the latest calculations in a saturation model. Ratios of transverse momentum spectra between backward and forward pseudorapidity are above unity for p{sub T} below 5 GeV/c. The ratio of central to peripheral spectra in d+Au collisions shows enhancement at 2 < p{sub T} < 6 GeV/c, with a larger effect at backward rapidity than forward rapidity. Our measurements are in qualitative agreement with gluon saturation and in contrast to calculations based on incoherent multiple partonic scatterings.
Date: January 12, 2005
Creator: Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
System: The UNT Digital Library
On the Significance of the Contribution of Multiple-Electron Capture Processes to Cometary X-Ray Emission (open access)

On the Significance of the Contribution of Multiple-Electron Capture Processes to Cometary X-Ray Emission

We report laboratory studies of the role played by multiple-electron capture (MEC) in solar wind induced cometary X-ray emission. Collisions of Ne{sup 10+} with He, Ne, Ar, CO, and CO{sub 2} have been investigated by means of the traditional singles X-ray spectroscopy in addition to the triple-coincidence measurements of X-rays, scattered projectile, and target recoil ions for the atomic targets. The coincidence measurements enable the reduction of the singles X-ray spectra into partial spectra originating in single-electron capture (SEC) and MEC collisions. The measurements provide unequivocal evidence for a significant role played by MEC, and strongly suggest that models based solely on SEC are bound to yield erroneous conclusions on the solar wind composition and velocities and on cometary atmospheres. The experimental relative importance of MEC collisions is compared with molecular classical-over-the-barrier model (MCBM), classical trajectory Monte Carlo (CTMC), and multi-channel Landau-Zener (MCLZ), calculations which can qualitatively reproduce the experimental trends.
Date: May 12, 2005
Creator: Ali, R.; Neill, P. A.; Beiersdorfer, P.; Harris, C. L.; Rakovi?, M. J.; Wang, J. G. et al.
System: The UNT Digital Library
Performance of 2nd Generation BaBar Resistive Plate Chambers (open access)

Performance of 2nd Generation BaBar Resistive Plate Chambers

The BaBar detector has operated nearly 200 Resistive Plate Chambers (RPCs), constructed as part of an upgrade of the forward endcap muon detector, for the past two years. The RPCs experience widely different background and luminosity-driven singles rates (0.01-10 Hz/cm{sup 2}) depending on position within the endcap. Some regions have integrated over 0.3 C/cm{sup 2}. RPC efficiency measured with cosmic rays is high and stable. The average efficiency measured with beam is also high. However, a few of the highest rate RPCs have suffered efficiency losses of 5-15%. Although constructed with improved techniques and minimal use of linseed oil, many of the RPCs, which are operated in streamer mode, have shown increased dark currents and noise rates that are correlated with the direction of the gas flow and the integrated current. Studies of the above aging effects are presented and correlated with detector operating conditions.
Date: July 12, 2005
Creator: Anulli, F.; Baldini, R.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Patteri, P. et al.
System: The UNT Digital Library
Dalitz Plot Analysis of D0 to K0K+ K- (open access)

Dalitz Plot Analysis of D0 to K0K+ K-

A Dalitz plot analysis of approximately 12,500 D{sup 0} events reconstructed in the hadronic decay D{sup 0} {yields} {bar K}{sup 0} K{sup +}K{sup -} is presented. This analysis is based on a data sample of 91.5 fb{sup -1} collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage rings at SLAC running at center-of-mass energies on and 40 MeV below the {Upsilon}(4S) resonance. The events are selected from e{sup +}e{sup -} {yields} c{bar c} annihilations using the decay D*{sup +} {yields} D{sup 0}{pi}{sup +}. The following ratio of branching fractions has been obtained: BR = {Lambda}(D{sup 0} {yields} {bar K}{sup 0}K{sup +}K{sup -})/{Lambda}(D{sup 0} {yields} {bar K}{sup 0}{pi}{sup +}{pi}{sup -}) = (15.8 {+-} 0.1(stat.) {+-} 0.5 (syst.)) x 10{sup -2}. Estimates of fractions and phases for resonant and non-resonant contributions to the Dalitz plot are also presented. The a{sub 0}(980) {yields} {bar K}K projection has been extracted with little background. A search for Cp asymmetries on the Dalitz plot has been performed.
Date: July 12, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Evidence for B+ to K0barK+ and B0 to K0K0bar, and Measurement of the Branching Fraction and Search for Direct CP Violation in B+ to K0pi+ (open access)

Evidence for B+ to K0barK+ and B0 to K0K0bar, and Measurement of the Branching Fraction and Search for Direct CP Violation in B+ to K0pi+

The authors present evidence for the b {yields} d penguin-dominated decays B{sup +} {yields} {bar K}{sup 0}K{sup +} and B{sup 0} {yields} K{sup 0}{bar K}{sup 0} with significances of 3.5 and 4.5 standard deviations, respectively. The results are based on a sample of 227 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. We measure the branching fractions {Beta}(B{sup +} {yields} {bar K}{sup 0}K{sup +}) = (1.5 {+-} 0.5 {+-} 0.1) x 10{sup -6} (< 2.4 x 10{sup -6}) and {Beta}(B{sup 0} {yields} K{sup 0}{bar K}{sup 0}) = (1.19{sub -0.35}{sup +0.40} {+-} 0.13) x 10{sup -6}, where the uncertainties are statistical and systematic, respectively, and the upper limit on the branching fraction for {bar K}{sup 0}K{sup +} is at the 90% confidence level. They also present improved measurements of the charge-averaged branching fraction {Beta}(B{sup +} {yields} K{sup 0}{pi}{sup +}) = (26.0 {+-} 1.3 {+-} 1.0) x 10{sup -6} and CP-violating charge asymmetry {Alpha}{sub CP} (K{sup 0}{pi}{sup +}) = -0.09 {+-} 0.05 {+-} 0.01, where the uncertainties are statistical and systematic, respectively.
Date: July 12, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Measurement of Branching Fractions and Mass Spectra of B to K pi pi gamma (open access)

Measurement of Branching Fractions and Mass Spectra of B to K pi pi gamma

The authors present a measurement of the partial branching fractions and mass spectra of the exclusive radiative penguin processes B {yields} K{pi}{pi}{gamma} in the range m{sub K{pi}{pi}} < 1.8 GeV/c{sup 2}. They reconstruct four final states: K{sup +}{pi}{sup -}{pi}{sup +}{gamma}, K{sup +}{pi}{sup -}{pi}{sup 0}{gamma}, K{sub S}{sup 0}{pi}{sup -}{pi}{sup +}{gamma}, and K{sub S}{sup 0}{pi}{sup +}{pi}{sup 0}{gamma}, where K{sub S}{sup 0} {yields} {pi}{sup +}{pi}{sup -}. Using 232 million e{sup +}e{sup -} {yields} B{bar B} events recorded by the BABAR experiment at the PEP-II asymmetric-energy storage ring, they measure the branching fractions {Beta}(B{sup +} {yields} K{sup +}{pi}{sup -}{pi}{sup +}{gamma}) = (2.95 {+-} 0.13(stat.) {+-} 0.20(syst)) x 10{sup -5}, {Beta}(B{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0}{gamma}) = (4.07 {+-} 0.22(stat.) {+-} 0.31(syst.)) x 10{sup -5}, {Beta}(B{sup 0} {yields} K{sup 0}{pi}{sup +}{pi}{sup -}{gamma}) = (1.85 {+-} 0.21(stat.) {+-} 0.12(syst.)) x 10{sup -5}, and {Beta}(B{sup +} {yields} K{sup 0}{pi}{sup +}{pi}{sup 0}{gamma}) = (4.56 {+-} 0.42(stat.) {+-} 0.31(syst.)) x 10{sup -5}.
Date: July 12, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Measurement of the Branching Fraction of B0 Meson Decay to a_1^+(1260) pi- (open access)

Measurement of the Branching Fraction of B0 Meson Decay to a_1^+(1260) pi-

We present a preliminary measurement of the branching fraction of the B meson decay B{sup 0} {yields} a{sub 1}{sup +}(1260){pi}{sup -}with a{sub 1}{sup +}(1260) {yields} {pi}{sup +}{pi}{sup +}{pi}{sup -}. The data sample corresponds to 218 x 10{sup 6} B{bar B} pairs produced in e{sup +}e{sup -} annihilation through the {Upsilon}(4S) resonance. We find the branching fraction (40.2 {+-} 3.9 {+-} 3.9) x 10{sup -6}, where the first error quoted is statistical and the second is systematic. The fitted values of the a{sub 1}(1260) parameters are m{sub a{sub 1}} = 1.22 {+-} 0.02 GeV/c{sup 2} and {Lambda}{sub a{sub 1}} = 0.423 {+-} 0.050 GeV/c{sup 2}.
Date: July 12, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Measurement of the Time-Dependent CP-Violating Asymmetry in $B^0 \to K^{0}_s\pi^0\gamma$ Decays (open access)

Measurement of the Time-Dependent CP-Violating Asymmetry in $B^0 \to K^{0}_s\pi^0\gamma$ Decays

We present a measurement of the time-dependent CP-violating asymmetry in B{sup 0} {yields} K*{sup 0}{gamma} decays with K*{sup 0} {yields} K{sub S}{sup 0}{pi}{sup 0} based on 232 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. In a sample containing 157 {+-} 16 signal decays, we measure S{sub K*{sup 0}{gamma}} = -0.21 {+-} 0.40 {+-} 0.05 and C{sub K*{sup 0}{gamma}} = -0.40 {+-} 0.23 {+-} 0.03, where the first error is statistical and the second systematic. We also explore B{sup 0} {yields} K{sub S}{sup 0}{pi}{sup 0}{gamma} decays with 1.1 < m{sub K{sub S}{sup 0}{pi}{sup 0}} < 1.8 GeV/c{sup 2} and find 59 {+-} 13 signal events with S{sub K{sub S}{sup 0}{pi}{sup 0}{gamma}} = 0.9 {+-} 1.0 {+-} 0.2 and C{sub K{sub S}{sup 0}{pi}{sup 0}{gamma}} = -1.0 {+-} 0.5 {+-} 0.2.
Date: July 12, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
DIII-D Diagnostic Systems (open access)

DIII-D Diagnostic Systems

None
Date: October 12, 2005
Creator: Boivin, R. L.; Luxon, J. L.; Austin, M. E.; Brooks, N. H.; Burrell, K. H.; Doyle, E. J. et al.
System: The UNT Digital Library
Solid-Solid Phase Transition Kinetics of FOX-7 (open access)

Solid-Solid Phase Transition Kinetics of FOX-7

Since it was developed in the late 1990s, 1,1-diamino-2,2-dinitroethene (FOX-7), with lower sensitivity and comparable performance to RDX, has received increasing interest. This paper will present our results for the phase changes of FOX-7 using DSC and HFC (Heat Flow Calorimetry). DSC thermal curves recorded at linear heating rates of 0.10, 0.35 and 1.0 C min{sup -1} show two endothermic peaks and two exothermic peaks. The two endothermic peaks represent solid-solid phase transitions, which have been observed in the literature at 114 C ({beta}-{gamma}) and 159 C ({gamma}-{delta}) by both DSC and XPD (X-ray powder diffraction) measurements. The first transition shifts from 114.5 to 115.8 C as the heating rate increases from 0.10 to 1.0 C min{sup -1}, while the second transition shifts from 158.5 to 160.4 C. Cyclical heating experiments show the endotherms and exotherms for a first heating through the {gamma} phase to the {delta} phase, a cooling and reversion to the {alpha} or {beta} phase, and a second heating to the {gamma} and {delta} phases. The data are interpreted using kinetic models with thermodynamic constraints.
Date: July 12, 2005
Creator: Burnham, A K; Weese, R K; Wang, R; Kwok, Q M & Jones, D G
System: The UNT Digital Library
CIRCE, the Proposed Coherent Infrared Center at the LawrenceBerkeley National Laboratory (open access)

CIRCE, the Proposed Coherent Infrared Center at the LawrenceBerkeley National Laboratory

At the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory (LBNL), we are proposing the construction of CIRCE (Coherent InfraRed Center), a ring-based photon source completely optimized for the generation of coherent synchrotron radiation (CSR) in the terahertz frequency range [1]. CIRCE exploits the full complement of the CSR-production mechanisms presently available for obtaining top performance, including a photon flux exceeding by more than nine orders of magnitude that of existing ''conventional'' broadband terahertz sources.
Date: July 12, 2005
Creator: Byrd, John M.; Martin, Michael M. & Sannibale, Fernando
System: The UNT Digital Library
POTENTIAL FOR HIGGS PHYSICS AT THE LHC AND SUPER-LHC. (open access)

POTENTIAL FOR HIGGS PHYSICS AT THE LHC AND SUPER-LHC.

The expected sensitivity of the LHC experiments to the discovery of the Higgs boson and the measurement of its properties is presented in the context of both the standard model and the its minimal supersymmetric extension. Prospects for a luminosity-upgraded ''Super-LHC'' are also presented. If it exists, the LHC should discover standard model Higgs boson, measure its mass accurately, and make various measurements of its couplings, spin and CP properties. In the context of the CP-conserving MSSM, the LHC should be able to discover one or more Higgs bosons over the entire m{sub A}-tan {beta} plane, with two or more observable in many cases. The large number of channels available insure a robust discovery and offer many opportunities for additional measurements. Observation of H {yields} {mu}{mu}, measurement of the tri-linear Higgs self-coupling, and various search channels are statistics-limited, and only possible with a luminosity upgrade. A luminosity upgrade would substantially improve some of the coupling measurements and generally extend the sensitivity in the MSSM Higgs plane. Efforts are ongoing to understand the upgrade of the LHC to the Super-LHC.
Date: December 12, 2005
Creator: CRANMER, K.S.
System: The UNT Digital Library
The growth of epitaxial uranium oxide observed by micro-Raman spectroscopy (open access)

The growth of epitaxial uranium oxide observed by micro-Raman spectroscopy

Raman spectroscopy can be performed with micrometer resolution and can thus be used to determine the dependence of oxide thickness on the substrate's grain structure or local impurity inclusions. The Raman signal amplitude emitted from an epitaxial uranium oxide layer as a function of oxide thickness has been modeled for light of 632.8 nm wavelength incident on the oxide and reflected from the uranium substrate using the optical properties determined by spectrophotometry. The model shows that the Raman signal increases with oxide thickness and saturates at about 150 nm thickness. The model was compared with the measured Raman signal amplitude of an epitaxial uranium oxide layer growing in air with a known time dependence of oxide growth.
Date: December 12, 2005
Creator: Caculitan, N & Siekhaus, W J
System: The UNT Digital Library
New developments for the site-specific attachment of protein to surfaces (open access)

New developments for the site-specific attachment of protein to surfaces

Protein immobilization on surfaces is of great importance in numerous applications in biology and biophysics. The key for the success of all these applications relies on the immobilization technique employed to attach the protein to the corresponding surface. Protein immobilization can be based on covalent or noncovalent interaction of the molecule with the surface. Noncovalent interactions include hydrophobic interactions, hydrogen bonding, van der Waals forces, electrostatic forces, or physical adsorption. However, since these interactions are weak, the molecules can get denatured or dislodged, thus causing loss of signal. They also result in random attachment of the protein to the surface. Site-specific covalent attachment of proteins onto surfaces, on the other hand, leads to molecules being arranged in a definite, orderly fashion and uses spacers and linkers to help minimize steric hindrances between the protein surface. This work reviews in detail some of the methods most commonly used as well as the latest developments for the site-specific covalent attachment of protein to solid surfaces.
Date: May 12, 2005
Creator: Camarero, J A
System: The UNT Digital Library
Measurements of Radiation Near An Atomic Spectral Line From the Interaction of a 30-GeV Electron Beam And a Long Plasma (open access)

Measurements of Radiation Near An Atomic Spectral Line From the Interaction of a 30-GeV Electron Beam And a Long Plasma

Emissions produced or initiated by a 30 GeV electron beam propagating through a {approx}1 m long heat pipe oven containing neutral and partially ionized vapor have been measured near atomic spectral lines in a beam-plasma wakefield experiment. The Cerenkov spatial profile has been studied as a function of oven temperature and pressure, observation wavelength, and ionizing laser intensity and delay. The Cerenkov peak angle is affected by the creation of plasma; estimates of plasma and neutral density have been extracted. Increases in visible background radiation consistent with increased plasma recombination emissions due to dissipation of wakefields were simultaneously measured.
Date: September 12, 2005
Creator: Catravas, P.; Chattopadhyay, S.; Esarey, E.; Leemans, W. P.; Assmann, R.; Decker, F. J. et al.
System: The UNT Digital Library
A Contract Based System For Large Data Visualization (open access)

A Contract Based System For Large Data Visualization

VisIt is a richly featured visualization tool that is used to visualize some of the largest simulations ever run. The scale of these simulations requires that optimizations are incorporated into every operation VisIt performs. But the set of applicable optimizations that VisIt can perform is dependent on the types of operations being done. Complicating the issue, VisIt has a plugin capability that allows new, unforeseen components to be added, making it even harder to determine which optimizations can be applied. We introduce the concept of a contract to the standard data flow network design. This contract enables each component of the data flow network to modify the set of optimizations used. In addition, the contract allows for new components to be accommodated gracefully within VisIt's data flow network system.
Date: April 12, 2005
Creator: Childs, H. R.; Brugger, E S; Bonnell, K S; Meredith, J S; Miller, M C; Whitlock, B J et al.
System: The UNT Digital Library
Registration and Fusion of X-Ray and Ultrasound Images for As-Built Modeling (open access)

Registration and Fusion of X-Ray and Ultrasound Images for As-Built Modeling

None
Date: September 12, 2005
Creator: Clark, G A & Jackson, J A
System: The UNT Digital Library
W-Band Sheet Beam Klystron Simulation (open access)

W-Band Sheet Beam Klystron Simulation

With the development of ever higher energy particle accelerators comes the need for compactness and high gradient, which in turn require very high frequency high power rf sources. Recent development work in W-band accelerating techniques has spurred the development of a high-power W-band source. Axisymmetric sources suffer from fundamental power output limitations (P{sub sat} {approx} {lambda}{sup 2}) brought on by the conflicting requirements of small beam sizes and high beam current. The sheet beam klystron allows for an increase in beam current without substantial increase in the beam current density, allowing for reduced cathode current densities and focusing field strengths. Initial simulations of a 20:1 aspect ratio sheet beam/cavity interaction using the 3 dimensional particle-in-cell code Magic3D have demonstrated a 35% beam-power to RF power extraction efficiency. Calculational work and numerical simulations leading to a prototype W-band sheet beam klystron will be presented, together with preliminary cold test structure studies of a proposed RF cavity geometry.
Date: September 12, 2005
Creator: Colby, E. R.; Caryotakis, G.; Fowkes, W. R. & Smithe, D. N.
System: The UNT Digital Library
STATISTICAL CHALLENGES FOR SEARCHES FOR NEW PHYSICS AT THE LHC. (open access)

STATISTICAL CHALLENGES FOR SEARCHES FOR NEW PHYSICS AT THE LHC.

Because the emphasis of the LHC is on 5{sigma} discoveries and the LHC environment induces high systematic errors, many of the common statistical procedures used in High Energy Physics are not adequate. I review the basic ingredients of LHC searches, the sources of systematics, and the performance of several methods. Finally, I indicate the methods that seem most promising for the LHC and areas that are in need of further study.
Date: September 12, 2005
Creator: Cranmer, Kyle
System: The UNT Digital Library
Accelerator Mass Spectrometry Allows for Cellular Quantification of Doxorubicin at Femtomolar Concentrations (open access)

Accelerator Mass Spectrometry Allows for Cellular Quantification of Doxorubicin at Femtomolar Concentrations

Accelerator mass spectrometry (AMS) is a highly sensitive analytical methodology used to quantify the content of radioisotopes, such as {sup 14}C, in a sample. The primary goals of this work were to demonstrate the utility of AMS in determining cellular [{sup 14}C]doxorubicin (DOX) concentrations and to develop a sensitive assay that is superior to high performance liquid chromatography (HPLC) for the quantification of DOX at the tumor level. In order to validate the superior sensitivity of AMS versus HPLC with fluorescence detection, we performed three studies comparing the cellular accumulation of DOX: one in vitro cell line study, and two in vivo xenograft mouse studies. Using AMS, we quantified cellular DOX content up to 4 hours following in vitro exposure at concentrations ranging from 0.2 pg/ml (345 fM) to 2 {micro}g/ml (3.45 {micro}M) [{sup 14}C]DOX. The results of this study show that, compared to standard fluorescence-based HPLC, the AMS method was over five orders of magnitude more sensitive. Two in vivo studies compared the sensitivity of AMS to HPLC using a nude mouse xenograft model in which breast cancer cells were implanted subcutaneously. After sufficiently large tumors formed, DOX was administered intravenously at two dose levels. Additionally, we tested the …
Date: April 12, 2005
Creator: DeGregorio, M W; Dingley, K H; Wurz, G T; Ubick, E & Turteltaub, K W
System: The UNT Digital Library
Two Rounds of Whole Genome Duplication in the Ancestral Vertebrate (open access)

Two Rounds of Whole Genome Duplication in the Ancestral Vertebrate

The hypothesis that the relatively large and complex vertebrate genome was created by two ancient, whole genome duplications has been hotly debated, but remains unresolved. We reconstructed the evolutionary relationships of all gene families from the complete gene sets of a tunicate, fish, mouse, and human, then determined when each gene duplicated relative to the evolutionary tree of the organisms. We confirmed the results of earlier studies that there remains little signal of these events in numbers of duplicated genes, gene tree topology, or the number of genes per multigene family. However, when we plotted the genomic map positions of only the subset of paralogous genes that were duplicated prior to the fish-tetrapod split, their global physical organization provides unmistakable evidence of two distinct genome duplication events early in vertebrate evolution indicated by clear patterns of 4-way paralogous regions covering a large part of the human genome. Our results highlight the potential for these large-scale genomic events to have driven the evolutionary success of the vertebrate lineage.
Date: April 12, 2005
Creator: Dehal, Paramvir & Boore, Jeffrey L.
System: The UNT Digital Library
Imaging of Tissue Micro-Structures using a Multi-Modal Microscope Design (open access)

Imaging of Tissue Micro-Structures using a Multi-Modal Microscope Design

We investigate a microscope design that offers high signal sensitivity and hyperspectral imaging capabilities and allows for implementation of various optical imaging approaches while its operational complexity is minimized. This system utilizes long working distance microscope objectives that enable for off-axis illumination of the tissue thereby allowing for excitation at any optical wavelength and nearly eliminating spectral noise from the optical elements. Preliminary studies using human and animal tissues demonstrate the feasibility of this approach for real-time imaging of intact tissue microstructures using autofluorescence and light scattering imaging methods.
Date: August 12, 2005
Creator: Demos, S G; Lieber, C A; Lin, B & Ramsamooj, R
System: The UNT Digital Library
Amplification of 1 ps Pulse Length Beam by Stimulated Raman Scattering of a 1 ns Beam in a Low Density Plasma (open access)

Amplification of 1 ps Pulse Length Beam by Stimulated Raman Scattering of a 1 ns Beam in a Low Density Plasma

The compression of a laser pulse by amplification of an ultra short pulse beam which seeds the stimulated Raman scatter of the first beam has been long been discussed in the context of solid and gas media. We investigate the possibility of using intersecting beams in a plasma to compress nanosecond pulses to picosecond duration by scattering from driven electron waves. Recent theoretical studies have shown the possibility of efficient compression with large amplitude, non-linear Langmuir waves driven either by SRS [1] or non-resonantly [2]. We describe experiments in which a plasma suitable for pulse compression is created, and amplification of an ultra short pulse beam is demonstrated.
Date: June 12, 2005
Creator: Dewald, E.; Kirkwood, R. K.; Niemann, C.; Meezan, N.; Wilks, S. C.; Divol, L. et al.
System: The UNT Digital Library
Practical Twistor Spinoffs: On-Shell Tree and Loop Recursion Relations (open access)

Practical Twistor Spinoffs: On-Shell Tree and Loop Recursion Relations

I briefly review how on-shell recursion relations, whose development was stimulated by recent twistor-space approaches, have been applied to compute tree and one-loop amplitudes in QCD.
Date: July 12, 2005
Creator: Dixon, Lance J.
System: The UNT Digital Library