Electrochemical NO{sub x} Sensors for Automotive Diesel Exhaust (open access)

Electrochemical NO{sub x} Sensors for Automotive Diesel Exhaust

New emissions regulations will increase the need for compact, inexpensive sensors for monitoring and control of automotive exhaust gas pollutants. Species of interest include hydrocarbons, carbon monoxide, and oxides of nitrogen (NO{sub x}). The current work is directed towards the development of fast, high sensitivity electrochemical NO{sub x} sensors for automotive diesel applications. We have investigated potentiometric NO sensors with good sensitivity and fast response when operated in 10% O{sub 2}. The sensors consist of yttria-stabilized zirconia substrates attached with NiCr{sub 2}O{sub 4} sensing electrodes and Pt reference electrodes. A composite NiCr{sub 2}O{sub 4}:Rh sensing electrode is shown to give significantly faster response than NiCr{sub 2}O{sub 4} alone. The exact role of the Rh in enhancing the response speed is not clear at present. However, the Rh appears to accumulate at the contacts between the NiCr{sub 2}O{sub 4} particles and may enhance the inter-particle electronic conduction. Ongoing testing of these sensors is being performed to elucidate the sensing mechanisms and to quantify cross sensitivity to, for example, NO{sub 2}.
Date: November 25, 2002
Creator: Martin, L. P.; Pham, A. Q. & Glass, R. S.
System: The UNT Digital Library
Status of Safety& Environmental Activities for Inertial Fusion Energy (open access)

Status of Safety& Environmental Activities for Inertial Fusion Energy

Over the past several years, significant progress has been made in the analysis of safety and environmental (S&E) issues for inertial fusion energy (IFE). Detailed safety assessments have been performed for the baseline power plant concepts, as well as for a conceptual target fabrication facility. Safety analysis results are helping to drive the agenda for experiments. A survey of the S&E characteristics--both radiological and chemical--of candidate target materials has been completed. Accident initiating events have been identified and incorporated into master logic diagrams, which will be essential to the detailed safety analyses that will be needed in the future. Studies of aerosol generation and transport will have important safety implications. A Monte Carlo-based uncertainty analysis procedure has been developed for use in neutron activation calculations. Finally, waste management issues are receiving increased attention and are deserving of further discussion.
Date: November 25, 2002
Creator: Latkowski, J. F.; Reyes, S.; Cadwallader, L. C.; Sharpe, J. P.; Marshall, T. D.; Merrill, B. J. et al.
System: The UNT Digital Library
Strategies and tools for whole genome alignments (open access)

Strategies and tools for whole genome alignments

The availability of the assembled mouse genome makespossible, for the first time, an alignment and comparison of two largevertebrate genomes. We have investigated different strategies ofalignment for the subsequent analysis of conservation of genomes that areeffective for different quality assemblies. These strategies were appliedto the comparison of the working draft of the human genome with the MouseGenome Sequencing Consortium assembly, as well as other intermediatemouse assemblies. Our methods are fast and the resulting alignmentsexhibit a high degree of sensitivity, covering more than 90 percent ofknown coding exons in the human genome. We have obtained such coveragewhile preserving specificity. With a view towards the end user, we havedeveloped a suite of tools and websites for automatically aligning, andsubsequently browsing and working with whole genome comparisons. Wedescribe the use of these tools to identify conserved non-coding regionsbetween the human and mouse genomes, some of which have not beenidentified by other methods.
Date: November 25, 2002
Creator: Couronne, Olivier; Poliakov, Alexander; Bray, Nicolas; Ishkhanov,Tigran; Ryaboy, Dmitriy; Rubin, Edward et al.
System: The UNT Digital Library
Calorimetry in CDF Run 2 (open access)

Calorimetry in CDF Run 2

The integrated calorimetry environment of CDF Run 2 comprises the Run 1 sampling scintillator calorimeters, electromagnetic preshower and shower maximum detectors, new scintillating-fiber endplug detectors, radioactive source calibration systems, dedicated trigger paths, and new custom front-end electronics. Together they form a general-purpose calorimetry system which was successfully commissioned in 2000/2001. The initial performance is described here, along with a glimpse of first CDF Run 2 data.
Date: October 25, 2002
Creator: Erbacher, R.
System: The UNT Digital Library
CDF - Secondary vertex trigger (open access)

CDF - Secondary vertex trigger

At the beginning of 2002 a new data taking with an upgraded trigger system started for the CDF collaboration. One of the major improvements is the track trigger. A fast processor reconstructs tracks in the central drift chamber and the Silicon Vertex Tracker combines these tracks with the silicon vertex detector information to have track parameters with a precision as good as the offine reconstruction. This system allows CDF to trigger on tracks significantly displaced from the primary vertex with high efficiency for signal events like charm and beauty and to keep low background rates. The performances, in terms of resolution and efficiency, of both the processors are illustrated and the firsts physics results are discussed.
Date: October 25, 2002
Creator: Lucchesi, D.
System: The UNT Digital Library
The CKM Experiment (open access)

The CKM Experiment

I describe the CKM experiment, a new initiative using the Fermilab Main Injector to obtain {approx} 100 events of the ultra-rare decay mode K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}}. The branching ratio will be used to extract |V*{sub ts}V{sub td}|. Due to the decay mode's theoretical cleanliness, it plays a key role in over-constraining the Standard Model description of CP violation.
Date: October 25, 2002
Creator: Nguyen, Hogan H.
System: The UNT Digital Library
A cryomodule for the RIA driver linac. (open access)

A cryomodule for the RIA driver linac.

We present a cryomodule design for the superconducting linacs for the proposed Rare Isotope Accelerator Facility (RIA). This paper discusses the design of a cryomodule for all the drift-tube-loaded superconducting cavities required for the machine. The same basic design will be used for the low and medium velocity sections of the driver linac and also for sections of the radioactive ion beam (RIB) linac. Fundamental design choices such as separate vs. common beam and insulating vacuum spaces are driven by the clean fabrication techniques required for optimum cavity performance. The design can be adapted to a variety of cavity geometries.
Date: October 25, 2002
Creator: Fuerst, J. D. & Shepard, K. W.
System: The UNT Digital Library
Disappearance of back-to-back high p {sub T} hadron correlations in central Au+Au collisions at {radical}s{sub NN} = 200 GeV (open access)

Disappearance of back-to-back high p {sub T} hadron correlations in central Au+Au collisions at {radical}s{sub NN} = 200 GeV

Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudo-rapidity range and full azimuth in Au+Au and p+p collisions at = {radical}s{sub NN} = 200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes already observed in elementary collisions. A strong back-to-back correlation exists for p+p and peripheral Au + Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.
Date: October 25, 2002
Creator: Adler, C.; Ahammed, Z.; Allgower, C.; Amonett, J.; Anderson, B. D.; Anderson, M. et al.
System: The UNT Digital Library
Kinetics of phase growth in Nb3Sn formation for heat treatment optimization (open access)

Kinetics of phase growth in Nb3Sn formation for heat treatment optimization

The kinetics of growth and superconducting properties of Nb{sub 3}Sn are investigated as a function of the heat treatment (HT) duration and temperature for Internal Tin and Powder-in-Tube strands at 650, 700 and 750 C. For all times and temperatures, the Nb{sub 3}Sn layer thickness is measured, the critical current at 4.2 K is tested as a function of magnetic field, and the upper critical field is evaluated. Results of the layer critical current density are also shown as a function of HT duration and temperature.
Date: October 25, 2002
Creator: Barzi, Emanuela & Mattafirri, Sara
System: The UNT Digital Library
Photon and jet physics at the Collider Detector at Fermilab (open access)

Photon and jet physics at the Collider Detector at Fermilab

We summarize recent Run 1 photon and jet measurements from p{bar b} collisions at {radical}s = 0.63 TeV and 1.8 TeV using data collected at the Collider Detector at Fermilab (CDF). First Run 2 results at {radical}s = 1.96 TeV are also presented together with predictions of the kinematic reach accessible with 15 fb{sup -1} of Run 2 data. Data are compared to the predictions of Quantum Chromodynamics (QCD).
Date: October 25, 2002
Creator: Dittmann, J.
System: The UNT Digital Library
Preventing and Removing Contamination in a Natural Radiocarbon Sample Preparation Laboratory (open access)

Preventing and Removing Contamination in a Natural Radiocarbon Sample Preparation Laboratory

The introduction of elevated {sup 14}C contamination into a natural radiocarbon sample preparation laboratory can occur through many different pathways. The most difficult to control is the introduction of contaminated samples from outside labs. Laboratories can remain {sup 14}C contaminated as a result of earlier tracer based research, even if ''hot'' work has not occurred in the laboratories in decades. Prior to accepting samples from outside collaborators, it is recommended that the collaborators test their labs for {sup 14}C contamination. Any surface in a lab that has high use by multiple people has the potential to be contaminated. The standard procedure for determining whether a collaborator's lab is contaminated consists of swiping lab surfaces with small glass fiber filters wetted with alcohol and measuring them for {sup 14}C content using AMS. Volatile {sup 14}C can be detected by using aerosol monitors consisting of fine soot that is depleted in {sup 14}C. These monitors can be set out in the laboratory in question to check for volatile {sup 14}C contamination. In the event that a hot sample is introduced in the natural radiocarbon sample prep laboratory, all sample submission should be stopped until the lab is declared clean. Samples already being …
Date: October 25, 2002
Creator: Zermeno, P.; Kurdyla, D. K.; Buchholz, B. A.; Heller, S. J.; Frantz, B. R.; Brown, T. A. et al.
System: The UNT Digital Library
Search for CP violation in hyperon decays. (open access)

Search for CP violation in hyperon decays.

Direct CP violation in nonleptonic hyperon decays can be established by comparing the decays of hyperons and anti-hyperons. For {Xi} decay to {Lambda} {pi} followed by {Lambda} to p{pi}, the proton distribution in the rest frame of Lambda is governed by the product of the decay parameters {alpha}{sub {Xi}} {alpha}{sub {Lambda}}. The asymmetry A{sub {Xi}{Lambda}}, proportional to the difference of {alpha}{sub {Xi}}{alpha}{sub {Lambda}} of the hyperon and anti-hyperon decays, vanishes if CP is conserved. We report on an analysis of a fraction of 1997 and 1999 data collected by the Hyper CP (E871) collaboration during the fixed-target runs at Fermilab. The preliminary measurement of the asymmetry is {Alpha}{sub {Xi}{Lambda}} = [-7 {+-} 12(stat) {+-} 6.2(sys)] x 10{sup -4}, an order of magnitude better than the present limit.
Date: October 25, 2002
Creator: Zyla, Piotr
System: The UNT Digital Library
Searches at the Tevatron (open access)

Searches at the Tevatron

Results of searches performed by CDF and D0 are presented. Most of the results are based on data taken during the 1994-95 data taking period (Run I), but some preliminary results from the current data taking period (Run II) are included.
Date: October 25, 2002
Creator: Orejudos, W.
System: The UNT Digital Library
Silicon detector upgrades for the Tevatron Run 2 (open access)

Silicon detector upgrades for the Tevatron Run 2

The current silicon devices being used by the D0 and CDF collaborations for the Tevatron Run 2a, which is expected to end in 2005 after accumulating about 2 fb{sup -1} of data, will need to be replaced due to radiation damage for the following data collection period designated as Run 2b. We will discuss these silicon replacement plans, the more uniform design of the detectors between D0 and CDF, and the current status of their fabrication.
Date: October 25, 2002
Creator: Kruse, M.
System: The UNT Digital Library
The sodium-cooled fast reactor (SFR). (open access)

The sodium-cooled fast reactor (SFR).

The primary mission for the SFR is the management of high-level wastes, and in particular, management of plutonium and other actinides. The Generation IV Roadmap Fuel Cycle Crosscut Group (FCCG) found that the limiting factor facing an essential role for nuclear energy with the once-through cycle is the availability of repository space worldwide [FCCG Report]. This becomes an important issue, requiring new repository development in only a few decades. Systems that employ a fully closed fuel cycle hold the promise to reduce repository space and performance requirements, although their costs must be held to acceptable levels. Closed fuel cycles, working alone or symbiotically with systems using a once-through cycle, permit partitioning the nuclear waste and management of each partitioned fraction. In the longer term, beyond 50 years, or if major new missions requiring nuclear energy production (such as a major growth in the use of hydrogen as an energy carrier) develop, uranium resource availability also becomes a limiting factor unless breakthroughs occur in mining or extraction technologies. Fast spectrum reactors have the ability to utilize almost all of the energy in the natural uranium versus the 1% utilized in thermal spectrum systems.
Date: October 25, 2002
Creator: Lineberry, M. J. & Allen, T. R.
System: The UNT Digital Library
Tevatron magnets and orbit vibrations (open access)

Tevatron magnets and orbit vibrations

We report results of recent measurements of vibrations of the Tevatron collider elements and orbit movements over large diapason of frequencies.
Date: October 25, 2002
Creator: Vladimir Shiltsev, Todd Johnson and Xiao-Long Zhang
System: The UNT Digital Library
Addressing Key Science and Technology Issues for IFE Chambers, Target Fabrication and Target Injection (open access)

Addressing Key Science and Technology Issues for IFE Chambers, Target Fabrication and Target Injection

Significant progress has been made in addressing critical issues for high repetition rate chambers, target fabrication and injection for inertial fusion energy (IFE) for both heavy ion and laser drivers. Research is being conducted in a coordinated manner by national laboratories, universities and industry. This paper provides an overview of U.S. research activities and discusses how interface considerations (such as beam propagation and target survival during injection) impact design choices.
Date: September 25, 2002
Creator: Meier, W. R.; Goodin, D. T.; Nobile, A.; Besenbruch, G.; Haynes, D.; Hoffer, J. et al.
System: The UNT Digital Library
An Electronic Flash Lamp System to Replace the Traditional, Explosively-Driven Light Source (open access)

An Electronic Flash Lamp System to Replace the Traditional, Explosively-Driven Light Source

Electronic flash lamps are being developed at the Lawrence Livermore National Laboratory (LLNL). These lamps are intended to replace the traditional explosively driven Argon-gas filled light sources (Argon candles) that are currently used to provide illumination for high speed rotating mirror-framing cameras. At Livermore, we are developing an electronic flash lamp system that can match or exceed the light output of a traditional Argon candle. These systems utilize a Plasma Arc Lamp developed by PRISM Science Inc of Chatham, MA, USA. In the past, high-speed photography requiring explosively driven light sources were a one-time-only event that destroyed fixtures and optical alignment. The electronic flash lamp system, utilizing the Plasma Arc Lamp, will replace the explosively driven lighting systems and provide the capability to dry run experimental setups and repeat tests without damage to the experimental set-up. The electronic flash lamp system eliminates the problem of collateral damage to the experiment and does not add to the overall amount of explosives needed for a single test. Since the Pulsed-Power driver is remotely located, only the flash lamp itself is destroyed when the explosive shot is fired. The flexible geometry of this light source also enables the user to create complex light …
Date: September 25, 2002
Creator: Stigman, W L; Kihara, R & Scarpetti, R D
System: The UNT Digital Library
Ferromagnetic Ga1-xMnxAs produced by ion implantation and pulsed laser melting (open access)

Ferromagnetic Ga1-xMnxAs produced by ion implantation and pulsed laser melting

None
Date: September 25, 2002
Creator: Scarpulla, M. A.; Dubon, O. D.; Yu, K. M.; Monteiro, O.; Pillai, M. R.; Aziz, M. J. et al.
System: The UNT Digital Library
Particle and Heat Transport in a Dense Wall-Confined MTF Plasma (Theory and Simulations) (open access)

Particle and Heat Transport in a Dense Wall-Confined MTF Plasma (Theory and Simulations)

Plasma beta in Magnetized Target Fusion (MTF) systems is sometimes much greater than 1, and the plasma may be in direct contact with the imploding liner. Plasma processes are strongly dominated by inter-particle collisions. Under such conditions, the plasma microturbulence, behavior of alpha particles, and plasma equilibria are very different from conventional fusion systems. The present paper contains the most comprehensive analysis of the corresponding phenomena to date. 2D numerical simulations of plasma convection in the targets of a diffuse pinch type demonstrate an onset of convection in this configuration.
Date: September 25, 2002
Creator: Ryutov, D. D.; Barnes, D. C.; Bauer, B. S.; Hammer, J. H.; Hartman, C. W.; Kirkpatrick, R. C. et al.
System: The UNT Digital Library
WSSX - A Joint U.S.-Russian Nuclear Counter-Terrorism Exchange (open access)

WSSX - A Joint U.S.-Russian Nuclear Counter-Terrorism Exchange

In 1994, the U. S. and Russian Federation governments formally agreed to exchange information on the safety and security of nuclear weapons. This agreement included three major elements, called Technical Working Groups (TWGs). TWG C deals with counter-terrorism. Its four assigned actions and U.S./Russian experience are reviewed in this paper. Although active exchange programs were created under TWGs A and B, involving workshops and laboratory-to-laboratory development projects, little work was initiated in TWG C, due to the sensitive nature of this information. After 9/11, however, it became clear that much could be gained by having each country share information to help solve the problem of nuclear proliferation among terrorist groups. Government-to-government meetings have reaffirmed the initial agreement to exchange information on this topic, and a number of joint project proposals are now under discussion. The Joint Steering Committee that oversees this exchange has approved approximately 20 projects. They include such topics as terrorist threat scenario development, detection of nuclear material and explosives in transportation containers, analysis of material mass and configuration, and consequence mitigation. It is expected that the joint development of these capabilities will enhance our ability to respond to a nuclear threat and to facilitate mutual assistance, should …
Date: September 25, 2002
Creator: Crites, T. R.
System: The UNT Digital Library
Attaining Tier 2 Emissions Through Diesel Engine and Aftertreatment Integration - Strategy and Experimental Results (open access)

Attaining Tier 2 Emissions Through Diesel Engine and Aftertreatment Integration - Strategy and Experimental Results

The feasibility of diesel engines to meet the stringent emissions regulations of 2007 and beyond is an important consideration for light trucks and other personal transportation vehicles. Integrated engine and aftertreatment systems have been developed at Detroit Diesel Corporation for multiple engine and vehicle platforms. Tier 2 emissions technologies have been demonstrated with significant fuel economy advantage compared to the respective production gasoline engines while maintaining excellent drivability.
Date: August 25, 2002
Creator: Aneja, R.; Bolton, B.; Hakim, N. & Pavlova-MacKinnon, Z.
System: The UNT Digital Library
Comparative Toxicity of Combined Particle and Semi-Volatile Organic Fractions of Gasoline and Diesel Emissions (open access)

Comparative Toxicity of Combined Particle and Semi-Volatile Organic Fractions of Gasoline and Diesel Emissions

Little is known about the relative health hazards presented by emissions from in-use gasoline and diesel engines. Adverse health effects have been ascribed to engine emissions on the basis of: (1) the presence of known toxic agents in emissions; (2) high-dose animal and bacterial mutagenicity tests; and (3) studies indicating gradients of health effects with proximity to roadways. Most attention has been given to the particulate fraction of emissions; little attention has been given to the semi-volatile organic fraction. However, the semi-volatile fraction overlaps the particulate fraction in composition and is always present in the vicinity of fresh emissions. Although the potential health effects of diesel emissions have been frequently studied and debated during the past 20 years (EPA, 2002), relatively little attention has been given to the toxicity of emissions from gasoline engines. In view of the considerable progress in cleaning up diesel emissions, it would be useful to compare the toxicity of emissions from contemporary on-road diesel technology with that of emissions from the in-use gasoline fleet that is well-accepted by the public. It would also be useful to have a set of validated tests for rapid, cost-effective comparisons of the toxicity of emission samples, both for comparisons …
Date: August 25, 2002
Creator: Mauderly, Joe; Seagrave, JeanClare; McDonald, Jacob; Gigliotti,Andrew; Nikula, Kristen; Seilkop, Steven et al.
System: The UNT Digital Library
Detailed Analysis and Control Issues of Homogeneous Charge Compression Ignition (HCCI) (open access)

Detailed Analysis and Control Issues of Homogeneous Charge Compression Ignition (HCCI)

Homogeneous charge compression ignition (HCCI) is a new combustion technology that may develop as an alternative to diesel engines with high efficiency and low NOx and particulate matter emissions. This paper describes the HCCI research activities being currently pursued at Lawrence Livermore National Laboratory and at the University of California Berkeley. Current activities include analysis as well as experimental work.
Date: August 25, 2002
Creator: Aceves, Salvador M.; Flowers, Daniel L.; Martinez-Frias, Joel; Espinosa-Loza, Francisco & Dibble, Robert
System: The UNT Digital Library