CHEMICAL SAFETY: ASKING THE RIGHT QUESTIONS (open access)

CHEMICAL SAFETY: ASKING THE RIGHT QUESTIONS

Recent reports have shown that, despite efforts to the contrary, chemical accidents continue to occur at an unacceptable rate and there is no evidence that this rate is decreasing. Based on this observation, one can conclude that previous analyses have not accurately identified and implemented appropriate fixes to eliminate identified root causes for chemical events. Based on this, it is time to reevaluate chemical accident data with a fresh eye and determine (a) what corrective actions have already been identified but have not been implemented, (b) what other root causes may be involved, and (c) what new corrective actions should be taken to eliminate these newly identified root causes.
Date: August 5, 2008
Creator: Simmons, F
Object Type: Article
System: The UNT Digital Library

Educating Consumers: New Content on Diesel Vehicles, Diesel Exhaust Fluid, and Selective Catalytic Reduction Technologies on the AFDC

Presentation covers new content available on the Alternative Fuels and Advanced Vehicle Data Center regarding diesel vehicles, diesel exhaust fluid, and selective catalytic reduction technologies.
Date: August 5, 2008
Creator: Brodt-Giles, D.
Object Type: Presentation
System: The UNT Digital Library
PHASE I SINGLE CELL ELECTROLYZER TEST RESULTS (open access)

PHASE I SINGLE CELL ELECTROLYZER TEST RESULTS

This document reports the results of Phase I Single Cell testing of an SO{sub 2}-Depolarized Water Electrolyzer. Testing was performed primarily during the first quarter of FY 2008 at the Savannah River National Laboratory (SRNL) using an electrolyzer cell designed and built at SRNL. Other facility hardware were also designed and built at SRNL. This test further advances this technology for which work began at SRNL in 2005. This research is valuable in achieving the ultimate goal of an economical hydrogen production process based on the Hybrid Sulfur (HyS) Cycle. The focus of this work was to conduct single cell electrolyzer tests to further develop the technology of SO{sub 2}-depolarized electrolysis as part of the HyS Cycle. The HyS Cycle is a hybrid thermochemical cycle that may be used in conjunction with advanced nuclear reactors or centralized solar receivers to produce hydrogen by water-splitting. Like all other sulfur-based cycles, HyS utilizes the high temperature thermal decomposition of sulfuric acid to produce oxygen and regenerate sulfur dioxide. The unique aspect of HyS is the generation of hydrogen in a water electrolyzer that is operated under conditions where dissolved sulfur dioxide depolarizes the anodic reaction, resulting in substantial voltage reduction. Low cell …
Date: August 5, 2008
Creator: Steimke, J & Timothy Steeper, T
Object Type: Report
System: The UNT Digital Library
Neutral Kaon Interferometry in Au+Au collisions at sqrt(s_NN) =200 GeV (open access)

Neutral Kaon Interferometry in Au+Au collisions at sqrt(s_NN) =200 GeV

We present the first statistically meaningful results fromtwo-K0s interferometry in heavy-ion collisions. A model that takes theeffect of the strong interaction into account has been used to fit themeasured correlation function. The effects of single and coupled channelwere explored. At the mean transverse mass m_T = 1.07 GeV, we obtain thevalues R = 4.09 +- 0.46 (stat.) +- 0.31 (sys) fm and lambda = 0.92 +-0.23 (stat) +- 0.13 (sys), where R and lambda are the invariant radiusand chaoticity parameters respectively. The results are qualitativelyconsistent with m_T systematics established with pions in a scenariocharacterized by a strong collective flow.
Date: August 5, 2006
Creator: Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type: Article
System: The UNT Digital Library
Measurement of B \to X \gamma Decays and Determination of |V_{td}/V_{ts}| (open access)

Measurement of B \to X \gamma Decays and Determination of |V_{td}/V_{ts}|

Using a sample of 383 million B{bar B} events collected by the BABAR experiment, they measure sums of seven exclusive final states B {yields} X{sub d(s)}{gamma}, where X{sub d}(X{sub s}) is a non-strange (strange) charmless hadronic system in the mass range 0.6-1.8 GeV/c{sup 2}. After correcting for unmeasured decay modes in this mass range, they obtain a branching fraction for b {yields} d{gamma} of (7.2 {+-} 2.7(stat.) {+-} 2.3(syst.)) x 10{sup -6}. Taking the ratio of X{sub d} to X{sub s} they find {Lambda}(b {yields} d{gamma})/{Lambda}(b {yields} s{gamma}) = 0.033 {+-} 0.013(stat.) {+-} 0.009(syst.), from which they determine |V{sub td}/V{sub ts}| = 0.177 {+-} 0.043.
Date: August 5, 2008
Creator: Collaboration, The BABAR & Aubert, B.
Object Type: Article
System: The UNT Digital Library
ATWS Transients for the 2400 MWt Gas-Cooled Fast Reactor (open access)

ATWS Transients for the 2400 MWt Gas-Cooled Fast Reactor

Reactivity transients have been analyzed with an updated RELAPS-3D (ver. 2.4.2) system model of the pin core design for the 2400MWt gas-cooled fast reactor (GCFR). Additional reactivity parameters were incorporated in the RELAP5 point-kinetics model to account for reactivity feedbacks due to axial and radial expansion of the core, fuel temperature changes (Doppler effect), and pressure changes (helium density changes). Three reactivity transients without scram were analyzed and the incidents were initiated respectively by reactivity ramp, loss of load, and depressurization. During the course of the analysis the turbine bypass model for the power conversion unit (PCU) was revised to enable a better utilization of forced flow cooling after the PCU is tripped. The analysis of the reactivity transients demonstrates the significant impact of the PCU on system pressure and core flow. Results from the modified turbine bypass model suggest a success path for the GCFR to mitigate reactivity transients without scram.
Date: August 5, 2007
Creator: Cheng, L. Y. & Ludewig, H.
Object Type: Report
System: The UNT Digital Library
Intelligent Control via Wireless Sensor Networks for Advanced Coal Combustion Systems (open access)

Intelligent Control via Wireless Sensor Networks for Advanced Coal Combustion Systems

Numerical Modeling of Solid Gas Flow, System Identification for purposes of modeling and control, and Wireless Sensor and Actor Network design were pursued as part of this project. Time series input-output data was obtained from NETL's Morgantown CFB facility courtesy of Dr. Lawrence Shadle. It was run through a nonlinear kernel estimator and nonparametric models were obtained for the system. Linear and first-order nonlinear kernels were then utilized to obtain a state-space description of the system. Neural networks were trained that performed better at capturing the plant dynamics. It is possible to use these networks to find a plant model and the inversion of this model can be used to control the system. These models allow one to compare with physics based models whose parameters can then be determined by comparing them against the available data based model. On a parallel track, Dr. Kumar designed an energy-efficient and reliable transport protocol for wireless sensor and actor networks, where the sensors could be different types of wireless sensors used in CFB based coal combustion systems and actors are more powerful wireless nodes to set up a communication network while avoiding the data congestion. Dr. Ahmadi's group studied gas solid flow in …
Date: August 5, 2007
Creator: Behal, Aman; Kumar, Sunil & Ahmadi, Goodarz
Object Type: Report
System: The UNT Digital Library
FULL-SCALE COLD CRUCIBLE TEST ON VITRIFICATION OF SAVANNAH RIVER SITE SB4 HLW SURROGATE (open access)

FULL-SCALE COLD CRUCIBLE TEST ON VITRIFICATION OF SAVANNAH RIVER SITE SB4 HLW SURROGATE

The full-scale cold crucible test on vitrification of sludge batch 4 (SB4) Savannah River Site HLW surrogate using a 418 mm inner diameter stainless steel crucible was carried-out for 66 hrs. Commercially available Frit 503-R4 (8 wt.% Li{sub 2}O, 16 wt.% B{sub 2}O{sub 3}, 76 wt.% SiO{sub 2}) was used as a glass forming additive at a calcine to frit ratio of 1:1 (50 wt.% calcine, 50 wt.% frit). Two portions of slurry prepared from frit and mixture of chemicals simulating waste in amount of {approx}750 kg and from frit and waste surrogate prepared by the SRT-MST-2007-00070 procedure in amount of {approx}1,300 kg with water content of {approx}27 and {approx}50 wt.%, respectively, was processed and {approx}875 kg of the vitrified product in total ({approx}415 + 460 kg) was obtained. Average parameters were as follows: vibration power - 121.6 to 134.1 kW, feed rate (capacity) - 25.1 to 39.8 kg/hr, glass pour rate (productivity) - 14.0 kg/hr specific energy expenses for feed processing - 4.8 to 3.4 kW x hr/kg, specific energy expenses for glass production (melting ratio) - 8.7 to 9.6 kW x hr/kg, specific glass productivity - 2453 kg/(m{sup 2} x d). The product was composed of major vitreous …
Date: August 5, 2008
Creator: Marra, J
Object Type: Article
System: The UNT Digital Library
CHARACTERIZATION OF VITRIFIED SAVANNAH RIVER SITE SB4 WASTE SURROGATE PRODUCED IN COLD CRUCIBLE (open access)

CHARACTERIZATION OF VITRIFIED SAVANNAH RIVER SITE SB4 WASTE SURROGATE PRODUCED IN COLD CRUCIBLE

Savannah River Site (SRS) sludge batch 4 (SB4) waste surrogate with high aluminum and iron content was vitrified with commercially available Frit 503-R4 (8 wt.% Li{sub 2}O, 16 wt.% B2O3, 76 wt.% SiO{sub 2}) by cold crucible inductive melting using lab- (56 mm inner diameter), bench- (236 mm) and large-scale (418 mm) cold crucible. The waste loading ranged between 40 and 60 wt.%. The vitrified products obtained in the lab-scale cold crucible were nearly amorphous with traces of unreacted quartz in the product with 40 wt.% waste loading and traces of spinel phase in the product with 50 wt.% waste loading. The glassy products obtained in the bench-scale cold crucible are composed of major vitreous and minor iron-rich spinel phase whose content at {approx}60 wt.% waste loading may achieve {approx}10 vol.%. The vitrified waste obtained in the large-scale cold crucible was also composed of major vitreous and minor spinel structure phases. No nepheline phase has been found. Average degree of crystallinity was estimated to be {approx}12 vol.%. Anionic motif of the glass network is built from rather short metasilicate chains and boron-oxygen constituent based on boron-oxygen triangular units.
Date: August 5, 2008
Creator: Marra, J
Object Type: Article
System: The UNT Digital Library
What Is the Largest Einstein Radius in the Universe? (open access)

What Is the Largest Einstein Radius in the Universe?

The Einstein radius plays a central role in lens studies as it characterizes the strength of gravitational lensing. In particular, the distribution of Einstein radii near the upper cutoff should probe the probability distribution of the largest mass concentrations in the universe. Adopting a triaxial halo model, we compute expected distributions of large Einstein radii. To assess the cosmic variance, we generate a number of Monte-Carlo realizations of all-sky catalogues of massive clusters. We find that the expected largest Einstein radius in the universe is sensitive to parameters characterizing the cosmological model, especially {sigma}{sub s}: for a source redshift of unity, they are 42{sub -7}{sup +9}, 35{sub -6}{sup +8}, and 54{sub -7}{sup +12} arcseconds (errors denote 1{sigma} cosmic variance), assuming best-fit cosmological parameters of the Wilkinson Microwave Anisotropy Probe five-year (WMAP5), three-year (WMAP3) and one-year (WMAP1) data, respectively. These values are broadly consistent with current observations given their incompleteness. The mass of the largest lens cluster can be as small as {approx} 10{sup 15} M{sub {circle_dot}}. For the same source redshift, we expect in all-sky {approx} 35 (WMAP5), {approx} 15 (WMAP3), and {approx} 150 (WMAP1) clusters that have Einstein radii larger than 2000. For a larger source redshift of 7, …
Date: August 5, 2008
Creator: Oguri, Masamune & Blandford, Roger D.
Object Type: Article
System: The UNT Digital Library
Radiological Risk Assessment for King County Wastewater Treatment Division (open access)

Radiological Risk Assessment for King County Wastewater Treatment Division

Staff of the King County Wastewater Treatment Division (WTD) have concern about the aftermath of a radiological dispersion event (RDE) leading to the introduction of significant quantities of radioactive material into the combined sanitary and storm sewer system in King County, Washington. Radioactive material could come from the use of a radiological dispersion device (RDD). RDDs include "dirty bombs" that are not nuclear detonations but are explosives designed to spread radioactive material (National Council on Radiation Protection and Measurements (NCRP) 2001). Radioactive material also could come from deliberate introduction or dispersion of radioactive material into the environment, including waterways and water supply systems. This document develops plausible and/or likely scenarios, including the identification of likely radioactive materials and quantities of those radioactive materials to be involved. These include 60Co, 90Sr, 137Cs, 192Ir, 226Ra, plutonium, and 241Am. Two broad categories of scenarios are considered. The first category includes events that may be suspected from the outset, such as an explosion of a "dirty bomb" in downtown Seattle. The explosion would most likely be heard, but the type of explosion (e.g., sewer methane gas or RDD) may not be immediately known. Emergency first responders must be able to quickly detect the radioisotopes …
Date: August 5, 2005
Creator: Strom, Daniel J.
Object Type: Report
System: The UNT Digital Library
A SPICE Model and Electrostatic Field Analysis of the MOS Turn-Off Thyristor (open access)

A SPICE Model and Electrostatic Field Analysis of the MOS Turn-Off Thyristor

This paper presents a circuit model and an electrostatic field analysis with an approximate model of the SDM170HK MOS turn-off thyristor (MTO) fabricated by Silicon Power Corporation. The circuit model consists of five cells, each containing two bipolar junction transistors and three resistors. The turn-off feature of the MTO was simulated by inserting an array of 21 Fairchild FDS6670A MOSFET importable sub-circuit components between the cathode and the turn-on gate. The model was then used to create a four-terminal sub-circuit component representing the MTO that can be readily imported into computer-aided circuit design programs such as PSPICE and Micro-Cap. The generated static I-V characteristics and simulated switching waveforms are shown. The electrostatic field analysis was done for the maximum operating voltage of 4.5 kV using the Ansoft Maxwell 3D field simulator. Electrostatic field magnitudes that exceed the nominal air breakdown threshold of 30 kV/cm were observed surrounding the simulated turn-off gate wire, the turn-off gate ring contact, and the cathode ring contact. The resulting areas of high fields are a concern, as arc track marks have been found on the inner surface of the ceramic insulator near the internal gate connections of a failed device.
Date: August 5, 2002
Creator: Kelly, D. Q.; Mayhall, D. J.; Wilson, M. J. & Lahowe, D. A.
Object Type: Report
System: The UNT Digital Library
Addressing Problems with Scene-Based Wave Front Sensing (open access)

Addressing Problems with Scene-Based Wave Front Sensing

Scene-Based Wave Front Sensing uses the correlation between successive subimages to determine phase aberrations which blur digital images. Adaptive Optics technology uses deformable mirrors to correct for these phase aberrations and make the images clearer. The correlation between temporal subimages gives tip-tilt information. If these images do not have identical image content, tip-tilt estimations may be incorrect. Motion detection is necessary to help avoid errors initiated by dynamic subimage content. In this document, I will discuss why edge detection fails as a motion detection method on low resolution images and how thresholding the normalized variance of individual pixels is successful for motion detection.
Date: August 5, 2003
Creator: Chan, C
Object Type: Report
System: The UNT Digital Library
Through Weld Inspection of Wrought Stainless Steel Piping Using Phased-Array Ultrasonic Probes. (open access)

Through Weld Inspection of Wrought Stainless Steel Piping Using Phased-Array Ultrasonic Probes.

A study was conducted to assess the ability of phased-array ultrasonic techniques to detect and accurately determine the size of flaws from the far-side of wrought austenitic piping welds. Far-side inspections of these welds are currently performed on a “best effort” basis and do not conform to ASME Code Section XI Appendix VIII performance demonstration requirements. For this study, four circumferential welds in 610mm diameter, 36mm thick ASTM A-358, Grade 304 vintage austenitic stainless steel pipe were examined. The welds were fabricated with varied welding parameters; both horizontal and vertical pipe orientations were used, with air and water backing, to simulate field welding conditions. A series of saw cuts, electro-discharge machined (EDM) notches, and implanted fatigue cracks were placed into the heat affected zones of the welds. The saw cuts and notches range in depth from 7.5% to 28.4% through-wall. The implanted cracks ranged in depth from 5% through wall to 64% through wall. The welds were examined with two phased-array probes, a 2.0 MHz transmit-receive longitudinal wave array and a 2.0 MHz transmit-receive shear wave array. These examinations showed that both phased-array transducers were able to detect and accurately length-size, but not depth size, all of the notches and …
Date: August 5, 2004
Creator: Anderson, Michael T.; Cumblidge, Stephen E. & Doctor, Steven R.
Object Type: Article
System: The UNT Digital Library
Coefficient of Thermal Expansion of the Beta and Delta Polymorphs of HMX (open access)

Coefficient of Thermal Expansion of the Beta and Delta Polymorphs of HMX

Dimensional changes related to temperature cycling of the beta and delta polymorphs of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) are important for a variety of applications. The coefficient of thermal expansion (CTE) of the beta and delta phases are measured and reported in this work over a temperature range of -20 C to 215 C. In addition, dimensional changes associated with the phase transition were measured, both through the transition and back down. Initially, differential scanning calorimetry (DSC) was used to investigate back conversion of the delta phase to the beta phase polymorph. The most successful approach was first to measure the amount of the beta to delta conversion, then after a given cooling period a repeat analysis, to measure the heat consumed by a second pass through the beta to delta phase transition. In addition, TMA is used to measure the dimensional change of a 0.20-gram sample of HMX during its initial heating and then three days later during a 2nd heating. This HMX shows the beta to delta phase transition a second time, thereby confirming the back conversion from delta to beta phase HMX.
Date: August 5, 2004
Creator: Weese, R K; Burnham, A K & Maienschein, J L
Object Type: Article
System: The UNT Digital Library
IEA Implementing Agreements and Annexes: A Guide for Building Technologies Program Managers (open access)

IEA Implementing Agreements and Annexes: A Guide for Building Technologies Program Managers

This guide presents insights and guidance from DOE’s gathered through longstanding and extensive participation in IEA implementing agreements (IAs) and annexes. Even though DOE has been a key participant in international research activities through the IEA since the 1970s, the experience, knowledge, and institutional memory associated with these activities can be lost or forgotten easily as key DOE managers retire or leave the department. The guide seeks to assemble in a single reference some of the learning that has occurred through participation in IEA IAs as a guide for BTP managers currently responsible for IAs and for those who might consider entering into new IEA activities in the future.
Date: August 5, 2008
Creator: Evans, Meredydd; Meier, Alan & Runci, Paul J.
Object Type: Report
System: The UNT Digital Library
Accretion onto the first stellar mass black holes (open access)

Accretion onto the first stellar mass black holes

The first stars, forming at redshifts z > 15 in minihalos with M {approx} 10{sup 5-6} M{sub {circle_dot}} may leave behind remnant black holes, which could conceivably have been the 'seeds' for the supermassive black holes observed at z {approx}< 7. We study remnant black hole growth through accretion, including for the first time the radiation emitted due to accretion, with adaptive mesh refinement cosmological radiation-hydrodynamical simulations. The effects of photo-ionization and heating dramatically affect the large-scale inflow, resulting in negligible mass growth. We compare cases with accretion luminosity included and neglected to show that accretion radiation drastically changes the environment within 100 pc of the black hole, increasing gas temperatures by an order of magnitude. Gas densities are reduced and further star formation in the same minihalo is prevented for the two hundred million years we followed. Without radiative feedback included most seed black holes do not gain mass as efficiently as has been hoped for in previous theories, implying that black hole remnants of Pop III stars in minihalos are not likely to be miniquasars. Most importantly, however, our calculations demonstrate that if these black holes are indeed accreting close to the Bondi-Hoyle rate with ten percent radiative …
Date: August 5, 2009
Creator: Alvarez, Marcelo A.; Wise, John H. & Abel, Tom
Object Type: Article
System: The UNT Digital Library
Albeni Falls Wildlife Mitigation Project, 2008 Annual Report. (open access)

Albeni Falls Wildlife Mitigation Project, 2008 Annual Report.

The Albeni Falls Interagency Work Group (AFIWG) was actively involved in implementing wildlife mitigation activities in late 2007, but due to internal conflicts, the AFIWG members has fractionated into a smaller group. Implementation of the monitoring and evaluation program continued across protected lands. As of 2008, The Albeni Falls Interagency Work Group (Work Group) is a coalition comprised of wildlife managers from three tribal entities (Kalispel Tribe, Kootenai Tribe, Coeur d Alene Tribe) and the US Army Corps of Engineers. The Work Group directs where wildlife mitigation implementation occurs in the Kootenai, Pend Oreille and Coeur d Alene subbasins. The Work Group is unique in the Columbia Basin. The Columbia Basin Fish and Wildlife Authority (CBFWA) wildlife managers in 1995, approved what was one of the first two project proposals to implement mitigation on a programmatic basis. The maintenance of this kind of approach through time has allowed the Work Group to implement an effective and responsive habitat protection program by reducing administrative costs associated with site-specific project proposals. The core mitigation entities maintain approximately 9,335 acres of wetland/riparian habitats in 2008.
Date: August 5, 2009
Creator: Soults, Scott
Object Type: Report
System: The UNT Digital Library
Nature Collections: Energy - Supplement and Websit Focussing on Scientific and Social Aspects of Energy Research (open access)

Nature Collections: Energy - Supplement and Websit Focussing on Scientific and Social Aspects of Energy Research

Journal article submitted as a final report - publication date August 2007
Date: August 5, 2009
Creator: Nature Publishing Group
Object Type: Report
System: The UNT Digital Library

Striving for a Standard Protocol for Preconditioning or Stabilization of Polycrystalline Thin Film Photovoltaic Modules

Stabilization/preconditioning promise stable performance. CV-derived depletion width changes & hysteresis appear linked to stability; dark exposure in forward bias emulates light exposure at 1-sun.
Date: August 5, 2009
Creator: del Cueto, J. A.; Deline, C. A.; Albin, D. S.; Rummel, S. R. & Anderberg, A.
Object Type: Presentation
System: The UNT Digital Library
System Dynamics and Control System for a High Bandwidth Rotary Actuator and Fast Tool Servo (open access)

System Dynamics and Control System for a High Bandwidth Rotary Actuator and Fast Tool Servo

This paper explores some of the system dynamics and control issues for a short-stroke rotary actuator that we designed and tested for a new fast tool servo referred to as the 10 kHz rotary fast tool servo. The use of a fast tool servo (FTS) with a diamond turning machine for producing non-axisymmetric or textured surfaces on a workpiece is well known. In a previous paper [1] the authors provide details on the mechanical design and trade-off issues that were considered during the design phase for the fast tool servo. At the heart of that machine is the normal-stress variable reluctance rotary actuator described in more detail in this paper. In addition to producing the torque that is needed for the 10 kHz rotary fast tool servo, the actuator produces a force and is therefore referred to as a hybrid rotary/linear actuator. The actuator uses bias and steering magnetic fluxes for linearizing the torque versus current relationship. Certain types of electric engraving heads use an actuator similar in principle to our hybrid actuator. In the case of the engraving heads, the actuator is used to produce and sustain a resonating mechanical oscillator. This is in sharp contrast to the arbitrary …
Date: August 5, 2005
Creator: Montesanti, R C & Trumper, D L
Object Type: Article
System: The UNT Digital Library
Magnetic Tools for Lab-on-a-chip Technologies (open access)

Magnetic Tools for Lab-on-a-chip Technologies

This study establishes a set of magnetics-based tools that have been integrated with microfluidic systems. The overall impact of the work begins to enable the rapid and efficient manipulation and detection of magnetic entities such as particles, picoliter-sized droplets, or bacterial cells. Details of design, fabrication, and theoretical and experimental assessments are presented. The manipulation strategy has been demonstrated in the format of a particle diverter, whereby micron-sized particles are actively directed into desired flow channels at a split-flow junction by means of integrated microelectromagnets. Magnetic detection has been realized by deploying Giant Magnetoresistance (GMR) sensors--microfabricated structures originally developed for use as readout elements in computer hard-drives. We successfully transferred the GMR technology to the lab-on-a-chip arena, and demonstrated the versatility of the concept in several important areas: real-time, integrated monitoring of the properties of multiphase droplet flows; rapid quantitative determination of the concentration of magnetic nanoparticles in droplets of ferrofluids; and high-speed detection of individual magnetic microparticles and magnetotactic bacteria. The study also includes novel schemes for hydrodynamic flow focusing that work in conjunction with GMR-based detection to ensure precise navigation of the sample stream through the GMR detection volume, therefore effectively establishing a novel concept of a microfabricated …
Date: August 5, 2006
Creator: Pekas, Nikola Slobodan
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The SPARX Project: R & D Activity Towards X-Rays FEL Sources (open access)

The SPARX Project: R & D Activity Towards X-Rays FEL Sources

SPARX is an evolutionary project proposed by a collaboration among ENEA-INFN-CNR-Universita di Roma Tor Vergata aiming at the construction of a FELSASE X-ray source in the Tor Vergata Campus. The first phase of the SPARX project, funded by Government Agencies, will be focused on R&D activity on critical components and techniques for future X-ray facilities as described in this paper.
Date: August 5, 2005
Creator: Alesini, D.; Bellaveglia, M.; Bertolucci, S.; Biagini, M. E.; Boni, R.; Boscolo, M. et al.
Object Type: Article
System: The UNT Digital Library
Unusual Pulsed X-Ray Emission from the Young, High Magnetic Field Pulsar PSR J1119--6127 (open access)

Unusual Pulsed X-Ray Emission from the Young, High Magnetic Field Pulsar PSR J1119--6127

We present XMM-Newton observations of the radio pulsar PSR J1119-6127, which has an inferred age of 1,700 yr and surface dipole magnetic field strength of 4.1 x 10{sup 13} G. We report the first detection of pulsed X-ray emission from PSR J1119-6127. In the 0.5-2.0 keV range, the pulse profile shows a narrow peak with a very high pulsed fraction of (74 {+-} 14)%. In the 2.0-10.0 keV range, the upper limit for the pulsed fraction is 28% (99% confidence). The pulsed emission is well described by a thermal blackbody model with a temperature of T{infinity} = 2.4{sub -0.2}{sup +0.3} x 10{sup 6} K and emitting radius of 3.4{sub -0.3}{sup +1.8} km (at a distance of 8.4 kpc). Atmospheric models result in problematic estimates for the distance/emitting area. PSR J1119-6127 is now the radio pulsar with smallest characteristic age from which thermal X-ray emission has been detected. The combined temporal and spectral characteristics of this emission are unlike those of other radio pulsars detected at X-ray energies and challenge current models of thermal emission from neutron stars.
Date: August 5, 2005
Creator: Gonzalez, M. E.; Kaspi, V. M.; Camilo, F.; Gaensler, B. M. & Pivovaroff, M. J.
Object Type: Article
System: The UNT Digital Library