Prospects for Electron Imaging with Ultrafast Time Resolution (open access)

Prospects for Electron Imaging with Ultrafast Time Resolution

Many pivotal aspects of material science, biomechanics, and chemistry would benefit from nanometer imaging with ultrafast time resolution. Here we demonstrate the feasibility of short-pulse electron imaging with t10 nanometer/10 picosecond spatio-temporal resolution, sufficient to characterize phenomena that propagate at the speed of sound in materials (1-10 kilometer/second) without smearing. We outline resolution-degrading effects that occur at high current density followed by strategies to mitigate these effects. Finally, we present a model electron imaging system that achieves 10 nanometer/10 picosecond spatio-temporal resolution.
Date: January 26, 2007
Creator: Armstrong, M R; Reed, B W; Torralva, B R & Browning, N D
System: The UNT Digital Library
Status of the Nif Power Conditioning System (open access)

Status of the Nif Power Conditioning System

The NIF Power Conditioning System provides the pulsed excitation required to drive flashlamps in the laser's optical amplifiers. Modular in design, each of the 192 Main Energy Storage Modules (MESMs) storage up to 2.2 MJ of electrical energy in its capacitor bank before delivering the energy to 20 pairs of flashlamps in a 400 {micro}s pulse (10% power points). The peak current of each MESM discharge is 0.5 MA. Production, installation, commissioning and operation of the NIF Power Conditioning continue to progress rapidly, with the goals of completing accelerated production in late 2007 and finishing commissioning by early 2008, all the while maintaining an aggressive operations schedule. To date, more than 80% of the required modules have been assembled, shipped and installed in the facility, representing more that 240 MJ of stored energy available for driving NIF flashlamps. The MESMs have displayed outstanding reliability during daily, multiple-shift operations.
Date: July 26, 2007
Creator: Arnold, P.; Hulsey, S.; Ullery, G.; Petersen, D.; Pendleton, D.; Ollis, C. et al.
System: The UNT Digital Library
A Search for B+ to tau+ nu (open access)

A Search for B+ to tau+ nu

The authors present a search for the decay B{sup +} {yields} {tau}{sup +}{nu} using 383 x 10{sup 6} B{bar B} pairs collected at the {Upsilon}(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. A sample of events with one reconstructed semileptonic B decay (B{sup -} {yields} D{sup 0}{ell}{sup -}{bar {nu}}{sub {ell}}X) is selected, and in the recoil a search for B{sup +} {yields} {tau}{sup +}{nu} is performed. The {tau} is identified in the following channels: {tau}{sup +} {yields} e{sup +}{nu}{bar {nu}}, {tau}{sup +} {yields} {mu}{sup +}{nu}{bar {nu}}, {tau}{sup +} {yields} {pi}{sup +} {bar {nu}} and {tau}{sup +} {yields} {pi}{sup +}{pi}{sup 0}{bar {nu}}. They measure a branching fraction of {Beta}(B{sup +} {yields} {tau}{sup +}{nu}) = (0.9 {+-} 0.6(stat.) {+-} 0.1(syst.)) x 10{sup -4}. In the absence of a significant signal, we calculate an upper limit at the 90% confidence level of {Beta}(B{sup +} {yields} {tau}{sup +}{nu}) < 1.7 x 10{sup -4}. They calculate the product of the B meson decay constant f{sub B} and |V{sub ub}| to be f{sub B} {center_dot} |V{sub ub}| = (7.2{sub -2.8}{sup +2.0}(stat.) {+-} 0.2(syst.)) x 10{sup -4} GeV.
Date: June 26, 2007
Creator: Aubert, B.
System: The UNT Digital Library
ELECTRICAL SAFETY IMPROVEMENT PROJECT A COMPLEX WIDE TEAMING INITIATIVE (open access)

ELECTRICAL SAFETY IMPROVEMENT PROJECT A COMPLEX WIDE TEAMING INITIATIVE

This paper describes the results of a year-long project, sponsored by the Energy Facility Contractors Group (EFCOG) and designed to improve overall electrical safety performance throughout Department of Energy (DOE)-owned sites and laboratories. As evidenced by focused metrics, the Project was successful primarily due to the joint commitment of contractor and DOE electrical safety experts, as well as significant support from DOE and contractor senior management. The effort was managed by an assigned project manager, using classical project-management principles that included execution of key deliverables and regular status reports to the Project sponsor. At the conclusion of the Project, the DOE not only realized measurable improvement in the safety of their workers, but also had access to valuable resources that will enable them to do the following: evaluate and improve electrical safety programs; analyze and trend electrical safety events; increase electrical safety awareness for both electrical and non-electrical workers; and participate in ongoing processes dedicated to continued improvement.
Date: November 26, 2007
Creator: BJ, GRAY
System: The UNT Digital Library
Superconducting Photoinjector (open access)

Superconducting Photoinjector

One of the frontiers in FEL science is that of high power. In order to reach power in the megawatt range, one requires a current of the order of one ampere with a reasonably good emittance. The superconducting laser-photocathode RF gun with a high quantum efficiency photocathode is the most natural candidate to provide this performance. The development of a 1/2 cell superconducting photoinjector designed to operate at up to a current of 0.5 amperes and beam energy of 2 MeV and its photocathode system are the subjects covered in this paper. The main issues are the photocathode and its insertion mechanism, the power coupling and High Order Mode damping. This technology is being developed at BNL for DOE nuclear physics applications such as electron cooling at high energy and electron ion colliders..
Date: August 26, 2007
Creator: Ben-Zvi,I.; Burrill, A.; Calaga, R.; Chang, X.; Grover, R.; Gupta, R. et al.
System: The UNT Digital Library
The Super Flavor Factory (open access)

The Super Flavor Factory

The main physics goals of a high luminosity e{sup +}e{sup -} flavor factory are discussed, including the possibilities to perform detailed studies of the CKM mechanism of quark mixing, and constrain virtual Higgs and Non-Standard Model particle contributions to the dynamics of rare B{sub u,d,s} decays. The large samples of D mesons and {tau} leptons produced at a flavor factory will result in improved sensitivities on D mixing and lepton flavor violation searches, respectively. One can also test fundamental concepts such as lepton universality to much greater precision than existing constraints and improve the precision on tests of CPT from B meson decays. Recent developments in accelerator physics have demonstrated the feasibility to build an accelerator that can achieve luminosities of {Omicron}(10{sup 36} cm{sup -2} s{sup -1}).
Date: January 26, 2007
Creator: Bevan, A.J. & /Queen Mary, U. of London
System: The UNT Digital Library
A review of ground-based heavy-ion radiobiology relevant to space radiation risk assessment: Part II. Cardiovascular and immunological effects (open access)

A review of ground-based heavy-ion radiobiology relevant to space radiation risk assessment: Part II. Cardiovascular and immunological effects

The future of manned space flight depends on an analysis of the numerous potential risks of travel into deep space. Currently no radiation dose limits have been established for these exploratory missions. To set these standards more information is needed about potential acute and late effects on human physiology from appropriate radiation exposure scenarios, including pertinent radiation types and dose rates. Cancer risks have long been considered the most serious late effect from chronic daily relatively low-dose exposures to the complex space radiation environment. However, other late effects from space radiation exposure scenarios are under study in ground-based accelerator facilities and have revealed some unique particle radiation effects not observed with conventional radiations. A comprehensive review of pertinent literature that considers tissue effects of radiation leading to functional detriments in specific organ systems has recently been published (NCRP National Council on Radiation Protection and Measurements, Information Needed to Make Radiation Protection Recommendations for Space Missions Beyond Low-Earth Orbit, Report 153, Bethesda, MD, 2006). This paper highlights the review of two non-cancer concerns from this report: cardiovascular and immunological effects.
Date: February 26, 2007
Creator: Blakely, Eleanor A. & Chang, Polly Y.
System: The UNT Digital Library
Magnetic Fields above the Surface of aSuperconductor with Internal Magnetism (open access)

Magnetic Fields above the Surface of aSuperconductor with Internal Magnetism

The author presents a method for calculating the magnetic fields near a planar surface of a superconductor with a given intrinsic magnetization in the London limit. He computes solutions for various magnetic domain boundary configurations and derives relations between the spectral densities of the magnetization and the resulting field in the vacuum half space, which are useful if the magnetization can be considered as a statistical quantity and its features are too small to be resolved individually. The results are useful for analyzing and designing magnetic scanning experiments. Application to existing data from such experiments on Sr{sub 2}RuO{sub 4} show that a domain wall would have been detectable, but the magnetic field of randomly oriented small domains and small defects may have been smaller than the experimental noise level.
Date: June 26, 2007
Creator: Bluhm, Hendrik & /Stanford U., Phys. Dept. /SLAC, SSRl
System: The UNT Digital Library
Effectiveness of Electrostatic Shielding and Electronic Subtraction to Correct for the Hole Trapping in Cdznte Semiconductor Detectors. (open access)

Effectiveness of Electrostatic Shielding and Electronic Subtraction to Correct for the Hole Trapping in Cdznte Semiconductor Detectors.

CdZnTe (CZT) is a very promising material for nuclear-radiation detectors. CZT detectors operate at ambient temperatures and offer high detection efficiency and excellent energy resolution, placing them ahead of high-purity Ge for those applications where cryogenic cooling is problematic. The progress achieved in CZT detectors over the past decade is founded on the developments of robust detector designs and readout electronics, both of which helped to overcome the effects of carrier trapping. Because the holes have low mobility, only electrons can be used to generate signals in thick CZT detectors, so one must account for the variation of the output signal versus the locations of the interaction points. To obtain high spectral resolution, the detector's design should provide a means to eliminate this dependence throughout the entire volume of the device. In reality, the sensitive volume of any ionization detector invariably has two regions. In the first, adjacent to the collecting electrode, the amplitude of the output signal rapidly increases almost to its maximum as the interaction point is located farther from the anode; in the rest of the volume, the output signal remains nearly constant. Thus, the quality of CZT detector designs can be characterized based on the magnitude …
Date: August 26, 2007
Creator: Bolotnikov, A. E.; Camarda, G. S.; Hossain, A.; Cui, Y. & James, R. B.
System: The UNT Digital Library
Bayesian Processing for the Detection of Radioactive Contraband from Uncertain Measurements (open access)

Bayesian Processing for the Detection of Radioactive Contraband from Uncertain Measurements

With the increase in terrorist activities throughout the world, the need to develop techniques capable of detecting radioactive contraband in a timely manner is a critical requirement. The development of Bayesian processors for the detection of contraband stems from the fact that the posterior distribution is clearly multimodal eliminating the usual Gaussian-based processors. The development of a sequential bootstrap processor for this problem is discussed and shown how it is capable of providing an enhanced signal for eventual detection.
Date: June 26, 2007
Creator: Candy, James V.; Sale, Kenneth; Guidry, Brian L.; Breitfeller, Eric; Manatt, Douglas & Chambers, David
System: The UNT Digital Library
Book Review Geostatistical Analysis of Compositional Data (open access)

Book Review Geostatistical Analysis of Compositional Data

Compositional data are represented as vector variables with individual vector components ranging between zero and a positive maximum value representing a constant sum constraint, usually unity (or 100 percent). The earth sciences are flooded with spatial distributions of compositional data, such as concentrations of major ion constituents in natural waters (e.g. mole, mass, or volume fractions), mineral percentages, ore grades, or proportions of mutually exclusive categories (e.g. a water-oil-rock system). While geostatistical techniques have become popular in earth science applications since the 1970s, very little attention has been paid to the unique mathematical properties of geostatistical formulations involving compositional variables. The book 'Geostatistical Analysis of Compositional Data' by Vera Pawlowsky-Glahn and Ricardo Olea (Oxford University Press, 2004), unlike any previous book on geostatistics, directly confronts the mathematical difficulties inherent to applying geostatistics to compositional variables. The book righteously justifies itself with prodigious referencing to previous work addressing nonsensical ranges of estimated values and error, spurious correlation, and singular cross-covariance matrices.
Date: March 26, 2007
Creator: Carle, S F
System: The UNT Digital Library
Large-timestep mover for particle simulations of arbitrarilymagnetized species (open access)

Large-timestep mover for particle simulations of arbitrarilymagnetized species

For self-consistent ion-beam simulations including electron motion, it is desirable to be able to follow electron dynamics accurately without being constrained by the electron cyclotron timescale. To this end, we have developed a particle-advance that interpolates between full particle dynamics and drift motion. By making a proper choice of interpolation parameter, simulation particles experience physically correct parallel dynamics, drift motion, and gyroradius when the timestep is large compared to the cyclotron period, though the effective gyro frequency is artificially low; in the opposite timestep limit, the method approaches a conventional Boris particle push. By combining this scheme with a Poisson solver that includes an interpolated form of the polarization drift in the dielectric response, the movers utility can be extended to higher-density problems where the plasma frequency of the species being advanced exceeds its cyclotron frequency. We describe a series of tests of the mover and its application to simulation of electron clouds in heavy-ion accelerators.
Date: March 26, 2007
Creator: Cohen, R. H.; Friedman, A.; Grote, D. P. & Vay, J. L.
System: The UNT Digital Library
Rare B Decays in Collider Experiments (open access)

Rare B Decays in Collider Experiments

The recent results on the semileptonic and leptonic rare B decays from the collider experiments are reviewed. Additionally, the recent measurements of lepton flavor violation in {tau} decays are presented.
Date: January 26, 2007
Creator: Cuhadar-Donszelmann, T. & U., /British Columbia
System: The UNT Digital Library
HYDROGEN TECHNOLOGY RESEARCH AT THE SAVANNAH RIVER NATIONAL LABORATORY, CENTER FOR HYDROGEN RESEARCH, AND THE HYDROGEN TECHNOLOGY RESEARCH LABORATORY (open access)

HYDROGEN TECHNOLOGY RESEARCH AT THE SAVANNAH RIVER NATIONAL LABORATORY, CENTER FOR HYDROGEN RESEARCH, AND THE HYDROGEN TECHNOLOGY RESEARCH LABORATORY

The Savannah River National Laboratory (SRNL) is a U.S. Department of Energy research and development laboratory located at the Savannah River Site (SRS) near Aiken, South Carolina. SRNL has over 50 years of experience in developing and applying hydrogen technology, both through its national defense activities as well as through its recent activities with the DOE Hydrogen Programs. The hydrogen technical staff at SRNL comprises over 90 scientists, engineers and technologists, and it is believed to be the largest such staff in the U.S. SRNL has ongoing R&D initiatives in a variety of hydrogen storage areas, including metal hydrides, complex hydrides, chemical hydrides and carbon nanotubes. SRNL has over 25 years of experience in metal hydrides and solid-state hydrogen storage research, development and demonstration. As part of its defense mission at SRS, SRNL developed, designed, demonstrated and provides ongoing technical support for the largest hydrogen processing facility in the world based on the integrated use of metal hydrides for hydrogen storage, separation and compression. The SRNL has been active in teaming with academic and industrial partners to advance hydrogen technology. A primary focus of SRNL's R&D has been hydrogen storage using metal and complex hydrides. SRNL and its Hydrogen Technology …
Date: February 26, 2007
Creator: Danko, E
System: The UNT Digital Library
Effect of Pre-Equilibrium Spin Distribution on 48Ti Cross Sections (open access)

Effect of Pre-Equilibrium Spin Distribution on 48Ti Cross Sections

None
Date: February 26, 2007
Creator: Dashdorj, D.; Kawano, T.; Garrett, P. E.; Becker, J. A.; Agvaanluvsan, U.; Bernstein, L. A. et al.
System: The UNT Digital Library
Thoughts on Verification of Nuclear Disarmament (open access)

Thoughts on Verification of Nuclear Disarmament

It is my pleasure to be here to day to participate in this Conference. My thanks to the organizers for preparing such an interesting agenda on a very difficult topic. My effort in preparing my presentation was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48. And as many of you know Lawrence Livermore National Laboratory is now, as of Oct 1st, under contract to the Lawrence Livermore National Security LLC. There has been a long history of how to view verification of arms control agreements. The basis for verification during the days of SALT was that verification would be based on each country's national technical means. For treaties dealing with strategic missiles this worked well as the individual items subject to verification were of such a size that they were visible by the National Technical Means available at the time. And it was felt that the counting of missiles and launchers could be verified by our National Technical Means. For nuclear testing treaties the use of seismic measurements developed into a capability that was reasonably robust for all but the smallest of nuclear tests. However, once we …
Date: September 26, 2007
Creator: Dunlop, W H
System: The UNT Digital Library
21nm X-Ray Laser Thomson Scattering of Laser-Heated Exploding Foil Plasmas (open access)

21nm X-Ray Laser Thomson Scattering of Laser-Heated Exploding Foil Plasmas

Recent experiments were carried out on the Prague Asterix Laser System (PALS) towards the demonstration of a soft x-ray laser Thomson scattering diagnostic for a laser-produced exploding foil. The Thomson probe utilized the Ne-like zinc x-ray laser which was double-passed to deliver {approx}1 mJ of focused energy at 21.2 nm wavelength and lasting {approx}100 ps. The plasma under study was heated single-sided using a Gaussian 300-ps pulse of 438-nm light (3{omega} of the PALS iodine laser) at laser irradiances of 10{sup 13}-10{sup 14} W cm{sup -2}. Electron densities of 10{sup 20}-10{sup 22} cm{sup -3} and electron temperatures from 200 to 500 eV were probed at 0.5 or 1 ns after the peak of the heating pulse during the foil plasma expansion. A flat-field 1200 line mm{sup -1} variable-spaced grating spectrometer with a cooled charge-coupled device readout viewed the plasma in the forward direction at 30{sup o} with respect to the x-ray laser probe. We show results from plasmas generated from {approx}1 {micro}m thick targets of Al and polypropylene (C{sub 3}H{sub 6}). Numerical simulations of the Thomson scattering cross-sections will be presented. These simulations show electron peaks in addition to a narrow ion feature due to collective (incoherent) Thomson scattering. The …
Date: September 26, 2007
Creator: Dunn, J.; Rus, B.; Mocek, T.; Nelson, A. J.; Foord, M. E.; Rozmus, W. et al.
System: The UNT Digital Library
Compulsory Deep Mixing of 3He and CNO Isotopes on the First Giant Branch (open access)

Compulsory Deep Mixing of 3He and CNO Isotopes on the First Giant Branch

We have found a deep-mixing process which occurs during First Giant Branch (FGB) evolution. It begins at the point in evolution where the surface convection zone (SCZ), having previously grown in size, starts to shrink, and it is driven by a local minimum that develops in the mean molecular weight as a result of the burning of {sup 3}He. This mixing can solve two important observational problems. One is why the interstellar medium (ISM) has not been considerably enriched in {sup 3}He since the Big Bang. The other is why products of nucleosynthesis such as {sup 13}C are progressively enriched on the upper FGB, when classical stellar modeling says that no further enrichment should take beyond the First Dredge-Up (FDU) episode, somewhat below the middle of the FGB.
Date: July 26, 2007
Creator: Eggleton, P P; Dearborn, D P & Lattanzio, J
System: The UNT Digital Library
Characterization of an AO-OCT system (open access)

Characterization of an AO-OCT system

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-volumetric-resolution, images of the retina. The AO-OCT system at UC Davis has been under development for 2 years and has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging [1]. The current system uses an AOptix bimorph deformable mirror (DM) for low-order, high-stroke correction [2] and a 140-actuator Boston Micromachines DM for high-order correction [3]. We are beginning to investigate the potential for increasing the image contrast in this system using higher-order wavefront correction. The first step in this analysis is to quantify the residual wavefront error (WFE) in the current system. Developing an error budget is a common tool for improved performance and system design in astronomical AO systems [4, 5]. The process for vision science systems is also discussed in several texts e.g. [6], but results from this type of analysis have rarely been included in journal articles on AO for vision science. Careful characterization of the AO system will lead to improved performance and inform the design of a future high-contrast system. In general, an AO system error budget must include an analysis of three categories …
Date: July 26, 2007
Creator: Evans, J. W.; Zawadzki, R. J.; Jones, S.; Olivier, S. & Werner, J. S.
System: The UNT Digital Library
Remarkable Strontium B-Site Occupancy in FerroelectricPb(Zr1-xTix)O3 Solid Solutions Doped with Cryolite-Type StrontiumNiobate (open access)

Remarkable Strontium B-Site Occupancy in FerroelectricPb(Zr1-xTix)O3 Solid Solutions Doped with Cryolite-Type StrontiumNiobate

New high-performance ferroelectric materials based on Pb(Zr{sub 1-x}Ti{sub x})O{sub 3} (PZT) that are doped with cryolite-type strontium niobate (SNO, Sr{sub 4}(Sr{sub 2-2y/3}Nb{sub 2+2y/3})O{sub 11+y}V{sub 0,1-y} with 0 {le} y {le} 1), hence denoted PZT:SNO, and their microscopic structure are described. The combination of exceptional piezoelectric properties, i.e. a piezoelectric strain constant of d{sub 33} {approx} 760 pm/V, with excellent stability and degradation resistance makes ferroelectric PZT:SNO solid solutions very attractive for use in novel and innovative piezoelectric actuator and transducer applications. Extended X-ray absorption fine-structure (EXAFS) analyses of PZT:SNO samples revealed that {approx}10 % of the Sr cations occupy the nominal B-sites of the perovskite-type PZT host lattice. This result was supported by EXAFS analyses of both a canonical SrTiO{sub 3} perovskite and two SNO model and reference compounds. Fit models that do not account for Sr cations on B-sites were ruled out. A clear Sr-Pb peak in Fourier transformed EXAFS data visually confirmed this structural model. The generation of temporary oxygen vacancies and the intricate defect chemistry induced by SNO-doping of PZT are crucial for the exceptional materials properties exhibited by PZT:SNO materials.
Date: April 26, 2007
Creator: Feltz, A.; Schmidt-Winkel, P.; Schossman, M.; Booth, C.H. & Albering, J.
System: The UNT Digital Library
Colliding with a crunching bubble (open access)

Colliding with a crunching bubble

In the context of eternal inflation we discuss the fate of Lambda = 0 bubbles when they collide with Lambda< 0 crunching bubbles. When the Lambda = 0 bubble is supersymmetric, it is not completely destroyed by collisions. If the domain wall separating the bubbles has higher tension than the BPS bound, it is expelled from the Lambda = 0 bubble and does not alter its long time behavior. If the domain wall saturates the BPS bound, then it stays inside the Lambda = 0 bubble and removes a finite fraction of future infinity. In this case, the crunch singularity is hidden behind the horizon of a stable hyperbolic black hole.
Date: March 26, 2007
Creator: Freivogel, Ben; Freivogel, Ben; Horowitz, Gary T. & Shenker, Stephen
System: The UNT Digital Library
Future GLAST Observations of Supernova Remnants And Pulsar Wind Nebulae (open access)

Future GLAST Observations of Supernova Remnants And Pulsar Wind Nebulae

Shell-type Supernova remnants (SNRs) have long been known to harbour a population of ultra-relativistic particles, accelerated in the Supernova shock wave by the mechanism of diffusive shock acceleration. Experimental evidence for the existence of electrons up to energies of 100 TeV was first provided by the detection of hard X-ray synchrotron emission as e.g. in the shell of the young SNR SN1006. Furthermore using theoretical arguments shell-type Supernova remnants have long been considered as the main accelerator of protons - Cosmic rays - in the Galaxy; definite proof of this process is however still missing. Pulsar Wind Nebulae (PWN) - diffuse structures surrounding young pulsars - are another class of objects known to be a site of particle acceleration in the Galaxy, again through the detection of hard synchrotron X-rays such as in the Crab Nebula. Gamma-rays above 100 MeV provide a direct access to acceleration processes. The GLAST Large Area telescope (LAT) will be operating in the energy range between 30 MeV and 300 GeV and will provide excellent sensitivity, angular and energy resolution in a previously rather poorly explored energy band. We will describe prospects for the investigation of these Galactic particle accelerators with GLAST.
Date: September 26, 2007
Creator: Funk, S.
System: The UNT Digital Library
Energy Dependent Morphology in the PWN Candidate HESS J1825-137 (open access)

Energy Dependent Morphology in the PWN Candidate HESS J1825-137

Observations with H.E.S.S. revealed a new source of very high-energy (VHE) gamma-rays above 100 GeV - HESS J1825-137 - extending mainly to the south of the energetic pulsar PSRB1823-13. A detailed spectral and morphological analysis of HESS J1825-137 reveals for the first time in VHE gamma-ray astronomy a steepening of the energy spectrum with increasing distance from the pulsar. This behavior can be understood by invoking radiative cooling of the IC-Compton gamma-ray emitting electrons during their propagation. In this scenario the vastly different sizes between the VHE gamma-ray emitting region and the X-ray PWN associated with PSRB1823-13 can be naturally explained by different cooling timescales for the radiating electron populations. If this scenario is correct, HESS J1825-137 can serve as a prototype for a whole class of asymmetric PWN in which the X-rays are extended over a much smaller angular scales than the gamma-rays and can help understanding recent detections of X-ray PWN in systems such as HESS J1640-465 and HESS J1813-178. The future GLAST satellite will probe lower electron energies shedding further light on cooling and diffusion processes in this source.
Date: September 26, 2007
Creator: Funk, S.; /KIPAC, Menlo Park; Hinton, J. A.; U., /Leeds; deJager, O. C. & /North West U., South Africa
System: The UNT Digital Library
Visual Analysis of Weblog Content (open access)

Visual Analysis of Weblog Content

In recent years, one of the advances of the World Wide Web is social media and one of the fastest growing aspects of social media is the blogosphere. Blogs make content creation easy and are highly accessible through web pages and syndication. With their growing influence, a need has arisen to be able to monitor the opinions and insight revealed within their content. In this paper we describe a technical approach for analyzing the content of blog data using a visual analytic tool, IN-SPIRE, developed by Pacific Northwest National Laboratory. We highlight the capabilities of this tool that are particularly useful for information gathering from blog data.
Date: March 26, 2007
Creator: Gregory, Michelle L.; Payne, Deborah A.; McColgin, Dave; Cramer, Nick O. & Love, Douglas V.
System: The UNT Digital Library