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Resident Assistant Training: A Southwestern Perspective

Description: Article discussing a study on the similarities and differences in public and private institutions training of resident assistants in the southwest United States.
Date: December 2001
Creator: Elleven, Russell K.; Allen, Jeff M. & Sarkees-Wircenski, Michelle
Partner: UNT College of Information

Structural and electronic properties of carbon nanotube tapers

Description: Article on structural and electronic properties of carbon nanotube tapers, a set of nanostructures comprised of straight tubular sections with decreasing diameters, joined to each other via conical funnels and terminated with a hemispherical cap.
Date: October 29, 2001
Creator: Meunier, Vincent; Buongiorno Nardelli, Marco; Roland, Christopher & Bernholc, Jerry
Partner: UNT College of Arts and Sciences

Rate coefficients and mechanistic analysis for the reaction of hydroxyl radicals with 1,1-dichloroethylene and trans-1,2-dichloroethylene over an extended temperature range

Description: Article on rate coefficients and mechanistic analysis for the reaction of hydroxyl radicals with 1,1-dichloroethylene and trans-1,2-dichloroethylene over an extended temperature range.
Date: July 17, 2001
Creator: Yamada, Takahiro; El-Sinawi, Abdulaziz; Siraj, Mohammad Masud, 1972-; Taylor, Philip H.; Peng, Jingping; Hu, Xiaohua et al.
Partner: UNT College of Arts and Sciences

Bulk band gaps in divalent hexaborides: A soft x-ray emission study

Description: Boron K-edge soft x-ray emission and absorption are used to address the fundamental question of whether divalent hexaborides are intrinsic semimetals or defect-doped bandgap insulators. These bulk sensitive measurements, complementary and consistent with surface-sensitive angle-resolved photoemission experiments, confirm the existence of a bulk band gap and the location of the chemical potential at the bottom of the conduction band.
Date: October 3, 2001
Creator: Denlinger, Jonathan D.; Gweon, Gey-Hong; Allen, James W.; Bianchi, Andrea D. & Fisk, Zachary
Partner: UNT Libraries Government Documents Department

Exposure Histories of Lunar Meteorites Northwest Africa 032 and DHOFAR 081

Description: Recent additions to the list of lunar meteorites include Northwest Africa (NWA) 032 and Dhofar 081. NWA 032 is an unbrecciated basalt, found in Morocco; Dhofar 081 is a fragmented feldspathic breccia, found in Oman. Our goal is the determination of the cosmic ray exposure history of these objects. Most lunar meteorites have complex cosmic ray exposure histories, having been exposed both at some depth on the lunar surface (2{pi} irradiation) before their ejection and as small bodies in space (4{pi} irradiation) during transport from the Moon to the Earth. These exposures were then followed by residence on the Earth's surface, the terrestrial residence time. Unraveling the complex history of these objects requires the measurement of at least four cosmogenic nuclides. The specific goals of these measurements are to constrain the depth of the sample at the time of ejection from the Moon, the transit time from the time of ejection to the time of capture by the Earth, and the residence time on the Earth's surface. These exposure durations in conjunction with the sample depth on the Moon can then be used to model impact and ejection mechanisms. To investigate the complex exposure histories of lunar meteorites, we measured cosmogenic nuclides, {sup 36}Cl (half-life = 3.01 x 10{sup 5} yr), {sup 26}Al (7.05 x 10{sup 5} yr), and {sup 10}Be (1.5 x 10{sup 6} yr) in NWA 032 and Dhofar 081. The measurements of {sup 41}Ca (1.04 x 10{sup 5} yr) are in progress.
Date: April 1, 2001
Creator: Nishiizumi, K. & Caffee, M.
Partner: UNT Libraries Government Documents Department


Description: A precision measurement of the anomalous g value, a{sub {mu}}=(g-2)/2, for the positive muon has been made using high intensity protons available at the Brookhaven AGS. The result based on the 1999 data a{sub {mu}}=11659202(14)(6) x 10{sup 10} (1.3ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a{sub {mu}} (SM)=11659159.6(6.7) x 10{sup 10} (0.57 ppm) and differ by over 2.5 standard deviation with experiment. Issues with reducing systematic errors and enhancing the injection and storage efficiencies are discussed.
Date: September 21, 2001
Partner: UNT Libraries Government Documents Department

Absence of X-point band overlap in divalent hexaborides and variability of the surface chemical potential

Description: Angle-resolved photoemission measurements of divalent hexaborides reveals a >1 eV X-point gap between the valence and conduction bands, in contradiction to the band overlap assumed in several models of their novel ferromagnetism. While the global ARPES band structure and gap size observed are consistent with the results of bulk-sensitive soft x-ray absorption and emission boron K-edge spectroscopy, the surface-sensitive photoemission measurements also show a variation with cation, surface and time of the position of the surface chemical potential in the band structure.
Date: November 4, 2001
Creator: Denlinger, Jonathan D.; Gweon, Gey-Hong; Mo, Sung-Kwan; Allen, James W.; Sarrao, John L.; Bianchi, Adrian D. et al.
Partner: UNT Libraries Government Documents Department

Consequences of return to power after a beam interruption in the blanket of an accelerator driven system.

Description: A sudden drop in power after a beam interruption leads to thermal fatigue effects in structural components in the blanket of an accelerator driven system. These thermal fatigue effects limit component lifetimes. A sudden return to power after a beam interruption can contribute significant additional thermal fatigue and greatly reduce component lifetimes. One obvious solution is a gradual return to power after a beam interruption. There are two potential problems with this solution. One problem involves interruptions that are longer than the thermal time constants of thin structural members but shorter than the time constants of thick structural members. In such a case, a gradual return to power reduces the additional thermal fatigue in the thin structural members but increases the thermal fatigue in thick structural members. Some compromise is necessary. The other problem is that for thick components with long thermal time constants a long, gradual return to power is required to minimize additional thermal fatigue. Such a slow return to power can reduce the utilization or the effective load factor of the system. Specific examples of beam interruptions with various assumptions on return to power are provided for a preliminary design for the blanket of the Accelerator Driven Test Facility. Also, mitigation options to increase component lifetime are discussed. These mitigation options include improving beam reliability and modifying the blanket design to better tolerate beam interruptions.
Date: August 9, 2001
Creator: Dunn, F.
Partner: UNT Libraries Government Documents Department

Users speak out on technology deployment

Description: This report summarizes user feedback data collected during a recent Accelerated Site Technology Deployment (ASTD) project: the Fluor Fernald ASTD Technology Deployment Project from May, 1999 through September, 2000. The main goal of the ASTD project was to use the ''Fernald approach'' to expedite the deployment of new or innovative technologies with superior safety, cost, and/or productivity benefits to Department of Energy (DOE) facilities. The Fernald approach targets technology end-users and their managers and directly involves them with hands-on demonstrations of new or innovative technologies during technology transfer sessions. The two technologies deployed through this project were the Personal Ice Cooling System (PICS) and the oxy-gasoline torch. Participants of technology transfer sessions were requested to complete feedback surveys. Surveys evaluated the effectiveness of the Fernald approach to technology deployment and assessed the responsiveness of employees to new technologies. This report presents the results of those surveys.
Date: February 25, 2001
Creator: Peters, Mark; Prochaska, Marty; Cromer, Paul & Zewatsky, Jennifer
Partner: UNT Libraries Government Documents Department


Description: 1.7 x 10{sup 8} x-ray photons per 3.5 ps pulse have been produced in Thomson scattering by focusing CO{sub 2} laser pulse on counter-propagating relativistic electron beam. We explore a possibility of further enhancement of process efficiency by propagating both beams in a plasma capillary. Conventional synchrotron light sources based on using giga-electron-volt electron synchrotron accelerators and magnetic wigglers generate x-ray radiation for versatile application in multi-disciplinary research. An intense laser beam causes relativistic electron oscillations similar to a wiggler. However, because the laser wavelength is thousand times shorter than a wiggler period, very moderate electron energy is needed to produce hard x-rays via Thomson scattering. This allows using relatively compact mega-electron-volt linear accelerators instead of giga-electron-volt synchrotrons. Another important advantage of Thomson sources is a possibility to generate femtosecond x-ray pulses whereas conventional synchrotron sources have typically {approx}300 ps pulse duration. This promises to revolutionize x-ray research in chemistry, physics, and biology expanding it to ultra-fast processes. Thomson sources do not compete in repetition rate and average intensity with conventional light sources that operate at the megahertz frequency. However, Thomson sources have a potential to produce much higher photon numbers per pulse. This may allow developing a single shot exposure important for structural analysis of live biological objects. The BNL Thomson source is a user's experiment conducted at the Accelerator Test Facility since 1998 by an international collaboration in High Energy Physics. Since inception, the ATF source produces the record peak x-ray yield, intensity and brightness among other similar proof-of-principle demonstrations attempted elsewhere. Note that this result is achieved with a moderate laser power of 15 GW. A key to this achievement is in choosing right apparatus and efficient interaction geometry. We use a CO{sub 2} laser that delivers 10 times more photons per unit energy than the 1-{micro}m ...
Date: December 3, 2001
Partner: UNT Libraries Government Documents Department

The CLAS Forward Electromagnetic Calorimeter

Description: The CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab utilizes six iron-free superconducting coils to provide an approximately toroidal magnetic field. The six sectors are instrumented individually to form six independent spectrometers. The forward region (8deg < (theta) < 45deg) of each sector is equipped with a lead-scintillator electromagnetic sampling calorimeter (EC), 16 radiation lengths thick, using a novel triangular geometry with stereo readout. With its good energy and position resolution, the EC is used to provide the primary electron trigger for CLAS. It is also used to reject pions, reconstruct pi-0 and eta decays and detect neutrons, This paper treats the design, construction and performance of the calorimeter.
Date: May 1, 2001
Creator: Amarian, M.; Asryan, Geram; Beard, Kevin; Brooks, Will; Burkert, Volker; Carstens, Tom et al.
Partner: UNT Libraries Government Documents Department

The incorporation of GIS in radiological transportation accident consequence assessments.

Description: Potential impacts of transportation accidents must be addressed in documents prepared under the National Environmental Protection Act (NEPA) as amended or in other environmental-related documents when the transportation of radioactive materials is considered. Estimating the potential human health consequences from the release and dispersion of radioactive materials following such an accident involves a number of interrelated computational models and a variety of input parameters. The RISKIND radiological transportation risk computer program [1] was developed to provide these types of estimates for local scenarios. However, it is often difficult to gain a full understanding of the initial problem and consequences by looking solely at numerical input and tables of results. To permit better-informed decisions, visualization of the site-specific geographic area and the potential spread of contamination can provide greater understanding. Thus, a geographic information system (GIS) component has been integrated with RISKIND to provide visualization capabilities as well as site-specific and computational benefits.
Date: June 26, 2001
Creator: Biwer, B. M.; LePoire, D. J.; Kuiper, J. A. & Chen, S. Y.
Partner: UNT Libraries Government Documents Department

Carbon sequestration with enhanced gas recovery: Identifying candidate sites for pilot study

Description: Depleted natural gas reservoirs are promising targets for carbon dioxide sequestration. Although depleted, these reservoirs are not devoid of methane, and carbon dioxide injection may allow enhanced production of methane by reservoir repressurization or pressure maintenance. Based on the favorable results of numerous simulation studies, we propose a field test of the Carbon Sequestration with Enhanced Gas Recovery (CSEGR) process. The objective of the field test is to evaluate the feasibility of CSEGR in terms of reservoir processes such as injectivity, repressurization, flow and transport of carbon dioxide, and enhanced production of methane. The main criteria for the field site include small reservoir volume and high permeability so that increases in pressure and enhanced recovery will occur over a reasonably short time period. The Rio Vista Gas Field in the delta of California's Central Valley offers potential as a test site, although we are currently looking broadly for other potential sites of opportunity.
Date: March 1, 2001
Creator: Oldenburg, C.M. & Benson, S.M.
Partner: UNT Libraries Government Documents Department

Strategies for cost-effective carbon reductions: A sensitivity analysis of alternative scenarios

Description: Analyses of alternative futures often present results for a limited set of scenarios, with little if any sensitivity analysis to identify the factors affecting the scenario results. This approach creates an artificial impression of certainty associated with the scenarios considered, and inhibits understanding of the underlying forces. This paper summarizes the economic and carbon savings sensitivity analysis completed for the Scenarios for a Clean Energy Future study (IWG, 2000). Its 19 sensitivity cases provide insight into the costs and carbon-reduction impacts of a carbon permit trading system, demand-side efficiency programs, and supply-side policies. Impacts under different natural gas and oil price trajectories are also examined. The results provide compelling evidence that policy opportunities exist to reduce carbon emissions and save society money.
Date: July 11, 2001
Creator: Gumerman, Etan; Koomey, Jonathan G. & Brown, Marilyn
Partner: UNT Libraries Government Documents Department

Electromagnetic Imaging of CO2 Sequestration at an Enhanced Oil Recovery Site

Description: Lawrence Livermore National Laboratory (LLNL) is currently involved in a long term study using time-lapse multiple frequency electromagnetic (EM) characterization at a waterflood enhanced oil recovery (EOR) site in California operated by Chevron Heavy Oil Division in Lost Hills, California (Figure 1). The petroleum industry's interest and the successful imaging results from this project suggest that this technique be extended to monitor CO{sub 2} sequestration at an EOR site also operated by Chevron. The impetus for this study is to develop the ability to image subsurface injected CO{sub 2} during EOR processes while simultaneously discriminating between pre-existing petroleum and water deposits. The goals of this study are to combine laboratory and field methods to image a pilot CO{sub 2} sequestration EOR site using the cross-borehole EM technique, improve the inversion process in CO{sub 2} studies by coupling results with petrophysical laboratory measurements, and focus on new gas interpretation techniques. In this study we primarily focus on how joint field and laboratory results can provide information on subsurface CO{sub 2} detection, CO{sub 2} migration tracking, and displacement of petroleum and water over time. This study directly addresses national energy issues in two ways: (1) the development of field and laboratory techniques to improve in-situ analysis of oil and gas enhanced recovery operations and, (2) this research provides a tool for in-situ analysis of CO{sub 2} sequestration, an international technical issue of growing importance.
Date: February 28, 2001
Creator: Kirkendall, B. & Roberts, J.
Partner: UNT Libraries Government Documents Department