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Modeling of the primary proton beamline of the Fermilab NuMI project (open access)

Modeling of the primary proton beamline of the Fermilab NuMI project

The 120 GeV primary proton beamline for the NuMI-MINOS [1] experiment at Fermilab will transport one of the most intense high-energy beams ever constructed. in parallel operation with the Collider program, 80% of the intensity capability of the Fermilab Main Injector can be sent to NuMI. Radiation safety pertaining to residual activity, damage of equipment and irradiation of groundwater is a primary concern. A particular challenge is that this beam will be transported to and targeted in a cavern excavated in rock in an aquifer region. A model of the beamline, including transport elements and excavated enclosures, has been built in the radiation simulation program MARS. This model has been used to determine limits for allowable beam loss, and to study effects of instabilities and of various failure types. Some results obtained with this model are presented.
Date: August 14, 2001
Creator: Striganov, Sergei; Childress, S.; Drozhdin, S.; Grossman, N.; Lucas, P. & Mokhov, N.
System: The UNT Digital Library
Experience with magnetic shielding of a large scale accelerator (open access)

Experience with magnetic shielding of a large scale accelerator

It is not unusual to place multiple accelerators in a common enclosure to save on civil construction costs. This often complicates operations, especially if accelerators are affecting each other. At Fermilab, the influence of a rapidly cycling Main Injector (MI) synchrotron on an antiproton storage ring (Recycler), placed in a common tunnel, was initially found to be unacceptable for a reliable operation of the Recycler. Initial closed orbit excursions in the Recycler ring during the MI ramp were in excess of 5 mm (rms). This paper describes a shielding technique, used to reduce these orbit excursions by a factor of five.
Date: August 14, 2001
Creator: al., Sergei Nagaitsev et
System: The UNT Digital Library
The deuteron: structure and form factors (open access)

The deuteron: structure and form factors

A brief review of the history of the discovery of the deuteron in provided. The current status of both experiment and theory for the elastic electron scattering is then presented.
Date: February 14, 2001
Creator: Garcon, M. & Orden, J.W. Van
System: The UNT Digital Library
NMIS Experience for Facility-To-Facility Transfer (open access)

NMIS Experience for Facility-To-Facility Transfer

One of the applications of template matching for arms control/warhead dismantlement transparency regimes is for monitoring facility-to-facility transfers. In 1999, three highly enriched uranium (HEU) weapons components for which the Nuclear Materials Identification System (NMIS) signatures had been obtained at the shipper's site were received at the Y-12 National Security Complex. The NMIS signatures obtained upon receipt of these items were compared with those at the shipper's site to confirm the identity of the item received. This paper describes the use of NMIS for these shipper-receiver confirmations.
Date: June 14, 2001
Creator: Mattingly, J. K.; Chiang, L. G.; Mullens, J. A. & Mihalczo, J. T.
System: The UNT Digital Library
Upgrade of the Wide-Angle Neutron Diffractometer at the High-Flux Isotope Reactor (open access)

Upgrade of the Wide-Angle Neutron Diffractometer at the High-Flux Isotope Reactor

The Wide-Angle Neutron Diffractometer (WAND) installed at the High-Flux Isotope Reactor (HFIR) has been upgraded for new experiments. The main feature of this upgrade is the replacement of its detector with a newly developed curved one-dimensional 3He position-sensitive counter composed of 624 individual anodes. From the results of test-measurements of the detector performance, it is found that the intrinsic angular resolution and the maximum neutron-counting rate per anode are 0.25 degrees and 2.0 x 10 counts/second, respectively.
Date: August 14, 2001
Creator: Ishii, Y.
System: The UNT Digital Library
Ductilization of Cr via Oxide Dispersions (open access)

Ductilization of Cr via Oxide Dispersions

Work by Scruggs et al. in the 1960's demonstrated that up to 20% tensile ductility could be achieved at room-temperature in sintered and extruded powder metallurgical Cr alloyed with MgO. During sintering, much of the MgO converts to a MgCr{sub 2}O{sub 4} spinel, which was hypothesized to getter nitrogen from the Cr, rendering it ductile. Recent efforts at Oak Ridge National Laboratory (ORNL) have succeeded in duplicating this original effect. Preliminary results suggest that the ductilization mechanism may be more complicated than the simple nitrogen gettering mechanism proposed by Scruggs, as some ductility was observed at room-temperature in Cr-MgO alloys containing nitride precipitates. Results of microstructural characterization and room-temperature mechanical property studies are presented for Cr-6MgO-(0-2.2)Ti wt.% as a function of hot-pressing and extrusion. Possible mechanisms by which the MgO additions may improve the room-temperature ductility of Cr are discussed.
Date: February 14, 2001
Creator: Brady, M.P.
System: The UNT Digital Library
Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels--Two-Year Results with Third-Generation Blowing Agents (open access)

Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels--Two-Year Results with Third-Generation Blowing Agents

Laboratory data are presented on the effect of constant-temperature aging on the apparent thermal conductivity of polyurethane foam insulation for refrigerators and freezers. The foam specimens were blown with HCFC-141b and with three of its potential replacements--HFC-134a, HFC-245fa, and cyclopentane. Specimens were aged at constant temperatures of 90 F, 40 F, and {minus}10 F. Thermal conductivity measurements were made on two types of specimens: full-thickness simulated refrigerator panels containing foam enclosed between solid plastic sheets, and thin slices of core foam cut from similar panels. Results are presented for the first two years of a multi-year aging study. Preliminary comparisons of measured data with predictions of a mathematical aging model are presented.
Date: February 14, 2001
Creator: Wilkes, K. E.
System: The UNT Digital Library
Natural Gas as a Future Fuel for Heavy-Duty Vehicles (open access)

Natural Gas as a Future Fuel for Heavy-Duty Vehicles

In addition to their significant environmental impacts, medium-duty and heavy-duty (HD) vehicles are high volume fuel users. Development of such vehicles, which include transit buses, refuse trucks, and HD Class 6-8 trucks, that are fueled with natural gas is strategic to market introduction of natural gas vehicles (NGV). Over the past five years the Department of Energy's (DOE) Office of Heavy Vehicle Technologies (OHVT) has funded technological developments in NGV systems to support the growth of this sector in the highly competitive transportation market. The goals are to minimize emissions associated with NGV use, to improve on the economies of scale, and to continue supporting the testing and safety assessments of all new systems. This paper provides an overview of the status of major projects under a program supported by DOE/OHVT and managed by Brookhaven National Laboratory. The discussion focuses on the program's technical strategy in meeting specific goals proposed by the N GV industry and the government. Relevant projects include the development of low-cost fuel storage, fueling infrastructure, and HD vehicle applications.
Date: May 14, 2001
Creator: Litzke, Wai-Lin & Wegrzyn, James
System: The UNT Digital Library
The DOE/NREL Next Generation Natural Gas Vehicle Program - An Overview (open access)

The DOE/NREL Next Generation Natural Gas Vehicle Program - An Overview

This paper summarizes the Next Generation Natural Gas Vehicle (NG-NGV) Program that is led by the U.S. Department Of Energy's (DOE's) Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The goal of this program is to develop and implement one Class 3-6 compressed natural gas (CNG) prototype vehicle and one Class 7-8 liquefied natural gas (LNG) prototype vehicle in the 2004 to 2007 timeframe. OHVT intends for these vehicles to have 0.5 g/bhp-hr or lower emissions of oxides of nitrogen (NOx) by 2004 and 0.2 g/bhp-hr or lower NOx by 2007. These vehicles will also have particulate matter (PM) emissions of 0.01 g/bhp-hr or lower by 2004. In addition to ambitious emissions goals, these vehicles will target life-cycle economics that are compatible with their conventionally fueled counterparts.
Date: May 14, 2001
Creator: Walkowicz, Kevin; Stephens, Denny & Stork, Kevin
System: The UNT Digital Library
Alpha-null defocus: An optimum defocus condition with relevance for focal-series reconstruction (open access)

Alpha-null defocus: An optimum defocus condition with relevance for focal-series reconstruction

Two optimum defocus conditions are used in high-resolution transmission electron microscopy. Scherzer defocus produces an image of the specimen ''projected potential'' to the resolution of the microscope, and Lichte defocus minimizes dispersion. A third optimum defocus is best for focal-series reconstruction; alpha-null defocus maximizes transfer of high-frequency diffracted beam amplitudes into the microscope image. Beam transfer is confined by incident-beam convergence to a Gaussian ''packet'' of defocus values centered on the alpha-null defocus. For a diffracted beam hkl, with a spatial frequency of u, the envelope for incident beam convergence has null damping effect when defocus is set to -Cs. (wavelength.u)**2. On either side of this alpha-null defocus value, the damping effect of incident-beam convergence reduces diffracted-beam transfer. The position of alpha-null defocus for any spatial frequency depends only on the value of Cs, but defocus-packet width around the alpha-null defocus depends only on the convergence semi-angle. Under NCEM OAM (one-Angstrom microscope) conditions, a [110] diamond image with the correct 0.89A spacing appears when the Si (004) alpha-null defocus is selected. The alpha-null defocus should be included as the (furthest underfocus) limit for all high-resolution focal series reconstruction.
Date: February 14, 2001
Creator: O'Keefe, Michael A.
System: The UNT Digital Library
Large aperture magnets for a future high power proton synchrotron (open access)

Large aperture magnets for a future high power proton synchrotron

A high intensity, high power proton synchrotron is currently under consideration at Fermilab. The machine--known as the Proton Driver--would accelerate 3 x 10{sup 13} protons from 400 MeV to 12 GeV (stage I) or 16 GeV (stage II) and ultimately deliver in excess of 1 MW of beam power. To minimize losses and insure beam stability, the space charge-induced tune shift must be kept well below 0.5. This is accomplished by spreading out bunches both longitudinally and transversely. While the former strategy favors high voltage low frequency RF, the latter leads to magnets with unconventionally large apertures. This requirement, combined with a 1.5 T bending field and rapid cycling operation results in a number of serious but not insurmountable challenges. In this paper, they discuss the design of the Proton Driver magnets and the rationale behind it.
Date: August 14, 2001
Creator: Mills, Jean-Francois Ostiguy and Frederick M.
System: The UNT Digital Library
Advanced Aerodynamic Devices to Improve the Performance, Economics, Handling, and Safety of Heavy Vehicles (open access)

Advanced Aerodynamic Devices to Improve the Performance, Economics, Handling, and Safety of Heavy Vehicles

Research is being conducted at the Georgia Tech Research Institute (GTRI) to develop advanced aerodynamic devices to improve the performance, economics, stability, handling and safety of operation of Heavy Vehicles by using previously-developed and flight-tested pneumatic (blown) aircraft technology. Recent wind-tunnel investigations of a generic Heavy Vehicle model with blowing slots on both the leading and trailing edges of the trailer have been conducted under contract to the DOE Office of Heavy Vehicle Technologies. These experimental results show overall aerodynamic drag reductions on the Pneumatic Heavy Vehicle of 50% using only 1 psig blowing pressure in the plenums, and over 80% drag reductions if additional blowing air were available. Additionally, an increase in drag force for braking was confirmed by blowing different slots. Lift coefficient was increased for rolling resistance reduction by blowing only the top slot, while downforce was produced for traction increase by blowing only the bottom. Also, side force and yawing moment were generated on either side of the vehicle, and directional stability was restored by blowing the appropriate side slot. These experimental results and the predicted full-scale payoffs are presented in this paper, as is a discussion of additional applications to conventional commercial autos, buses, motor …
Date: May 14, 2001
Creator: Englar, Robert J.
System: The UNT Digital Library
The influence of cut off lows on sulfate burdens over the North Atlantic during April, 1987 (open access)

The influence of cut off lows on sulfate burdens over the North Atlantic during April, 1987

The authors have presented examples from a modeling study of the development of sulfur burdens over North America, the North Atlantic Ocean and Europe during April, 1987 using observation-derived meteorological data to represent the actual conditions for this period, focusing on the influence of cut-off lows on SO{sub 2} and sulfate column burdens over the North Atlantic Ocean. The analysis demonstrates that these systems can serve either as sources or sinks of sulfate, and that the major factor governing their resulting effect is the position during its formative stages relative to (a) sources of moisture, and (b) sulfur emissions, which regulates the availability of sulfur, cloud liquid water for sulfur oxidation, and the amount of precipitation for sulfate removal produced in the later stages of the life cycle.
Date: January 14, 2001
Creator: Benkovitz, C. M.; Miller, M. A.; Schwartz, S. E. & Kwon, O. U.
System: The UNT Digital Library
Cummins Light Truck Diesel Engine Progress Report (open access)

Cummins Light Truck Diesel Engine Progress Report

Cummins has studied requirements of the Light Truck Automotive market in the United States and believes that the proposed V-family of engines meets those needs. Design and development of the V-family engine system continues and has expanded. The engine system is a difficult one, since the combined requirements of a very fuel-efficient commercial diesel, and the performance and sociability requirements of a gasoline engine are needed. Results of testing show that the engine can meet requirements for fuel economy and emissions in the Tier 2 interim period from 2004 to 2008. Advanced results show that the full Tier 2 results for 2008 and beyond can be achieved on a laboratory basis.
Date: May 14, 2001
Creator: Stang, John H.; Koeberlein, David E. & Ruth, Michael J.
System: The UNT Digital Library
An investigation of the effect of sulfate on cloud microphysics using a chemistry/transport model (open access)

An investigation of the effect of sulfate on cloud microphysics using a chemistry/transport model

Here the authors have used the output of a chemistry/transport model to identify a situation in which sulfate aerosol from industrial sources may be expected to exert a strong influence on cloud microphysical and radiative properties in an oceanic area that is well displaced from source regions. Pertinent cloud microphysical properties (optical depth and cloud drop radius) are inferred from radiance data obtained from satellite remote sensing. Comparison of these quantities in situations where the model indicates the presence or absence of industrial sulfate has allowed identification of the expected signature of one aerosol indirect effect--an increase in droplet number concentration and concomitant decrease in droplet radii, on a synoptic scale. Although the information obtained on changes in cloud optical depth is too meager to draw conclusions regarding radiative forcing, there is no doubt that the cloud microphysical properties are influenced by the incursion of continental sulfate aerosol in a way that is consistent with that expected by the Twomey indirect forcing mechanism.
Date: January 14, 2001
Creator: Wei, H. D.; Green, R.; Schwartz, S. E. & Benkovitz, C. M.
System: The UNT Digital Library
The Role of cavitation on Initiating Mercury-Steel Wetting (open access)

The Role of cavitation on Initiating Mercury-Steel Wetting

In accelerator-driven neutron sources such as the Spallation Neutron Source (SNS) with powers in the 2 MW range (time-averaged), the interaction of the energetic proton beam with the mercury target can lead to very high heating rates in the target. Although the resulting temperature rise is relatively small (a few degrees C), the rate of temperature rise is enormous (-10{sup 7} C/s) during the very brief beam pulse (-0.58 {micro}s). The resulting thermal-shock induced compression of the mercury leads to the production of large amplitude pressure waves in the mercury that interact with the walls of the mercury target and the bulk flow field. Understanding and predicting propagation of pressure pulses in the target are considered critical for establishing the feasibility of constructing and safely operating such devices. Safety-related operational concerns exist in two main areas, viz., (1) possible target enclosure failure from impact of thermal shocks on the wall due to its direct heating from the proton beam and the loads transferred from the mercury compression waves, and (2) impact of the compression-cum-rarefaction wave-induced effects such as cavitation bubble emanation and their impact on mercury-steel interfacial phenomena (such as wetting, mass transfer and erosion).
Date: November 14, 2001
Creator: Taleyarkhan, R.P.
System: The UNT Digital Library
Correlation of Nanoindentation and Conventional Mechanical Property Measurements (open access)

Correlation of Nanoindentation and Conventional Mechanical Property Measurements

A series of model ferritic alloys and two commercial steels were used to develop a correlation between tensile yield strength and nano-indentation hardness measurements. The NanoIndenter-II{reg_sign} was used with loads as low as 0.05 g{sub f} (0.490 mN) and the results were compared with conventional Vickers microhardness measurements using 200 and 500 g{sub f} (1.96 and 4.90 N) loads. Two methods were used to obtain the nanohardness data: (1) constant displacement depth and (2) constant load. When the nanohardness data were corrected to account for the difference between projected and actual indenter contact area, good correlation between the Vickers and nanohardness measurements was obtained for hardness values between 0.7 and 3 GPa. The correlation based on constant nanoindentation load was slightly better than that based on constant nanoindentation displacement. Tensile property measurements were made on these same alloys, and the expected linear relationship between Vickers hardness and yield strength was found, leading to a correlation between measured changes in nanohardness and yield strength changes.
Date: February 14, 2001
Creator: Rice, P. M.
System: The UNT Digital Library
New experimental results in proton radioactivity (open access)

New experimental results in proton radioactivity

A review of experimental data obtained recently on proton-radioactive nuclei is presented. The highlights include the observation of fine structure in proton emission, for the decays of {sup 131}Eu, {sup 145}Tm and {sup 145}Tm, and the studies of the excited states in proton-emitting nuclei. The observation limits are extended to few nanobarns cross sections ({sup 140}Ho, {sup 164}In and {sup 130}Eu) and few microsecond half-lives (e.g. {sup 145}Tm). Measured decay properties for thirty nine proton-emitting ground and isomeric states contributed to the understanding of nuclear masses and evolution of single-particle states at and beyond the proton drip-line. Experimental results have stimulated new theoretical approaches to proton emission and the structure of unbound narrow resonance states.
Date: August 14, 2001
Creator: Rykaczewski, K. P.
System: The UNT Digital Library
An Evaluation of Through-Thickness Changes in Primary Damage Production in Commercial Reactor Pressure Vessels (open access)

An Evaluation of Through-Thickness Changes in Primary Damage Production in Commercial Reactor Pressure Vessels

An extensive database of atomic displacement cascades in iron has been developed using the method of molecular dynamics (MD). More than 300 simulations have been completed at 100K with energies between 0.1 and 100 keV. This encompasses nearly all energies relevant to fission reactor irradiation environments since a 100 keV MD cascade corresponds to the average iron cascade following a collision with a 5.1 MeV neutron. Extensive statistical analysis of the database has determined representative average values for several primary damage parameters: the total number of surviving point defects, the fraction of the surviving point defects contained in clusters formed during cascade cooling, and a measure of the size distribution of the in-cascade point defect clusters. The cascade energy dependence of the MD-based primary damage parameters has been used to obtain spectrum-averaged defect production cross sections for typical fission reactor neutron energy spectra as a function of depth through the reactor pressure vessel. The attenuation of the spectrum-averaged cross sections for total point defect survival and the fraction of either interstitials or vacancies in clusters are quite similar to that for the NRT dpa. However, the cross sections derived to account for the energy dependence of the point defect cluster …
Date: February 14, 2001
Creator: Stoller, R. E.
System: The UNT Digital Library
Effect of Internal Alpha Radiation on Borosilicate Glass Containing Simulated Radioactive Waste (open access)

Effect of Internal Alpha Radiation on Borosilicate Glass Containing Simulated Radioactive Waste

To evaluate borosilicate glass as a matrix for long-term storage of radioactive waste, samples containing 45 wt. percent simulated waste along with 0.5 wt. percent 244Cm or 1 wt. percent 238Pu as alpha particle emitters were synthesized. A glass containing 238Pu without simulated waste was also made. Effects of internal alpha radiolysis from 244Cm and 238Pu on physical stability, leachability, and dilatation of the glasses were examined. Results confirm that glass may be a desirable matrix for fixing SRP radioactive waste for long-term storage. Internal alpha radiolysis and helium accumulation in the small samples did not significantly damage the glass. Actual values for helium solubility and permeability would be necessary, however, to determine whether helium accumulation might eventually damage larger glass monoliths during long-term storage.
Date: March 14, 2001
Creator: Bibler, N.E.
System: The UNT Digital Library
The DOE/NREL Environmental Science Program (open access)

The DOE/NREL Environmental Science Program

This paper summarizes the several of the studies in the Environmental Science Program being sponsored by DOE's Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The goal of the Environmental Science Program is to understand atmospheric impacts and potential health effects that may be caused by the use of petroleum-based fuels and alternative transportation fuels from mobile sources. The Program is regulatory-driven, and focuses on ozone, airborne particles, visibility and regional haze, air toxics, and health effects of air pollutants. Each project in the Program is designed to address policy-relevant objectives. Current projects in the Environmental Science Program have four areas of focus: improving technology for emissions measurements; vehicle emissions measurements; emission inventory development/improvement; ambient impacts, including health effects.
Date: May 14, 2001
Creator: Lawson, Douglas R. & Gurevich, Michael
System: The UNT Digital Library
Tapered undulator for SASE FELs (open access)

Tapered undulator for SASE FELs

We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission (SASE), where the radiation tends to have a relatively broad bandwidth, limited temporal phase coherence, and large amplitude fluctuations. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of a tapered undulator for parameters corresponding to the existing Argonne low-energy undulator test line (LEUTL) FEL. We also study possible tapering options for proposed x-ray FELs such as the Linac Coherent Light Source (LCLS).
Date: September 14, 2001
Creator: Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je & Vinokurov, Nikolai A.
System: The UNT Digital Library
Rare Decay Results from KTeV and ({rho}{sub CKM}, {eta}{sub CKM}) (open access)

Rare Decay Results from KTeV and ({rho}{sub CKM}, {eta}{sub CKM})

Rare decay results from KTeV are reviewed, emphasizing modes that in principle provide information about the CKM matrix. The KTeV results shown here are from the 1997 data sample, which consists of about 2.7 x 10{sup 11} K{sub L}{sup 0} decay samples. KTeV also took data in 1999, giving a total data sample about 2.5 times what is presented here for three body decays and about 3.2 times what is presented here for four body decays. A summary of the KTeV detector is in the Appendix. Our recent results in lepton flavor violating modes are also presented.
Date: February 14, 2001
Creator: Bellantoni, L.
System: The UNT Digital Library
RHIC PERFORMANCE. (open access)

RHIC PERFORMANCE.

The Brookhaven Relativistic Heavy Ion Collider (RHIC) is the first hadron accelerator and collider consisting of two independent rings. It is designed to operate at high collision luminosity over a wide range of beam energies and with particle species ranging from polarized protons to heavy ions. Construction of RHIC was officially completed in 1999. An overview of the status of commissioning and machine performance for the first operation period with gold beams is given.
Date: January 14, 2001
Creator: Roser, T.
System: The UNT Digital Library