States

RbGd{sub 2}Br{sub 7}:Ce scintillators for gamma ray and thermal neutron detection (open access)

RbGd{sub 2}Br{sub 7}:Ce scintillators for gamma ray and thermal neutron detection

In this paper, we report on gamma ray and thermal neutron detection with RbGd2Br7:Ce scintillators. RbGd2Br7:Ce (RGB) is a new scintillator material, which shows high light output (56,000 photons/MeV) and has a fast principal decay constant (45 ns) when doped with 10 percent Ce. These properties make RGB an attractive scintillator for g-ray detection. Also, due to the presence of Gd as a constituent, RGB has a high cross section for thermal neutron absorption and can achieve close to 100 percent stopping efficiency with 0.5 mm thick RGB crystals. Crystals of RGB with three different Ce concentrations (0.1, 5, and 10 percent) have been grown and their basic scintillation properties such as light output, decay time, and emission spectrum have been measured. In addition, high efficiency thermal neutron detection has been confirmed in our studies.
Date: December 25, 2001
Creator: Shah, Kanai S.; Cirignano, Leonard; Grazioso, Ronald; Klugerman, Misha; Bennett, Paul R.; Gupta, Tapan K. et al.
Object Type: Article
System: The UNT Digital Library
Extra dimensions vs. supersymmetric interpretation of missing energy events at a linear collider (open access)

Extra dimensions vs. supersymmetric interpretation of missing energy events at a linear collider

The photon plus missing energy signature is a primary handle on two important classes of theories. Theories with large extra dimensions predict the production of photons in association with Kaluza-Klein excitations of the graviton. In supersymmetric theories with superlight gravitinos, photons can be produced in association with gravitino pairs. The signatures for these two theories are compared, and it is found that they can be distinguished by studying the photon energy distributions and scaling of the cross section with center-of-mass energy. Both these methods fail, however, if there are six extra dimensions. In that case, additional phenomena predicted by the theories would be required to narrow down the underlying causes of the photon plus missing energy signal. We also study the ability of these measurements to determine the number of extra dimensions.
Date: October 25, 2001
Creator: Gopalakrishna, Shrihari; Perelstein, Maxim & Wells, James D.
Object Type: Article
System: The UNT Digital Library
Fabrication of ORNL Fuel Irradiated in the Peach Bottom Reactor and Postirradiation Examination of Recycle Test Elements 7 and 4 (open access)

Fabrication of ORNL Fuel Irradiated in the Peach Bottom Reactor and Postirradiation Examination of Recycle Test Elements 7 and 4

Seven full-sized Peach Bottom Reactor. fuel elements were fabricated in a cooperative effort by Oak Ridge National Laboratory (ORNL) and Gulf General Atomic (GGA) as part of the National HTGR Fuel Recycle Development Program. These elements contain bonded fuel rods and loose beds of particles made from several combinations of fertile and fissile particles of interest for present and future use in the High-Temperature Gas-Cooled Reactor (HTGR). The portion of the fuel prepared for these elements by ORNL is described in detail in this report, and it is in conjunction with the GGA report (GA-10109) a complete fabrication description of the test. In addition, this report describes the results obtained to date from postirradiation examination of the first two elements removed from the Peach Bottom Reactor, RTE-7 and -4. The fuel examined had relatively low exposure, up to about 1.5 x 10{sup 21} neutrons/cm* fast (>0.18 MeV) fluence, compared with the peak anticipated HTGR fluence of 8.0 x 10{sup 21}, but it has performed well at this exposure. Dimensional data indicate greater irradiation shrinkage than expected from accelerated test data to higher exposures. This suggests that either the method of extrapolation of the higher exposure data back to low exposure …
Date: October 25, 2001
Creator: Long, E. L. Jr.
Object Type: Report
System: The UNT Digital Library
FY2001 Annual Self Evaluation Report for the Pacific Northwest National Laboratory (open access)

FY2001 Annual Self Evaluation Report for the Pacific Northwest National Laboratory

This report provides year end status of PNNL performance against the FY01 critical outcomes.
Date: October 25, 2001
Creator: Labarge, Randy R.; Kuhl-Klinger, Kristine J. & Metcalf, Nancy W.
Object Type: Report
System: The UNT Digital Library
FY2001 Annual Self Evaluation Report for the Pacific Northwest National Laboratory (open access)

FY2001 Annual Self Evaluation Report for the Pacific Northwest National Laboratory

This report provides year end status of PNNL performance against the FY01 critical outcomes.
Date: October 25, 2001
Creator: Labarge, Randy R; Kuhl-Klinger, Kristine J & Metcalf, Nancy W
Object Type: Report
System: The UNT Digital Library
High-frequency Probing Diagnostic for Hall Current Plasma Thrusters (open access)

High-frequency Probing Diagnostic for Hall Current Plasma Thrusters

High-frequency oscillations (1-100 MHz) in Hall thrusters have apparently eluded significant experimental scrutiny. A diagnostic setup, consisting of a single Langmuir probe, a special shielded probe connector-positioner, and an electronic impedance-matching circuit, was successfully built and calibrated. Through simultaneous high-frequency probing of the Hall thruster plasma at multiple locations, high-frequency plasma waves have been identified and characterized for various thruster operating conditions.
Date: October 25, 2001
Creator: Litvak, A.A.; Raitses, Y. & Fisch, N.J.
Object Type: Report
System: The UNT Digital Library
KDP Impurity Data (open access)

KDP Impurity Data

Attached are the impurity data for 20-liter growth runs N. Zaitseva/L. Carman made in the 1996-1997 time frame for which we have both solution and crystal data. The 5 impurities added for the runs are AI(III), Cr(III), Fe(III), Mo(VI), and Sb(V). As an explanation of the tables, I report all impurity concentrations as ppb (ng/g{sub KDP}) with respect to dry KDP (even solution data.) ''MDL'' stands for ''Method Detection Limit.'' Nominal uncertainties are 1 MDL or 10% of the quoted value, whichever is greater. If the measured value is less than the MDL, I report ''ND,'' for ''Not Detected.'' If the value is greater than the MDL, but less than twice the MDL, I report ''D,'' for ''Detected.'' If the value is more than twice the MDL, I report two significant figures. The values come from ICP-ES and ICP-MS measurements. I give the detection limit for the more sensitive technique in the table under the ''MDL'' heading. In case where only one technique was used, I give the MDL for that technique in parentheses after the impurity value in the table. Since these measurements were made, changes in instrumentation have resulted in significant improvements in many of the detection limits. …
Date: October 25, 2001
Creator: Torres, R A
Object Type: Report
System: The UNT Digital Library
Low Bandwidth Vocoding using EM Sensor and Acoustic Signal Processing (open access)

Low Bandwidth Vocoding using EM Sensor and Acoustic Signal Processing

Low-power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference [1]. By combining these data with the corresponding acoustic signal, we've demonstrated an almost 10-fold bandwidth reduction in speech compression, compared to a standard 2.4 kbps LPC10 protocol used in the STU-III (Secure Terminal Unit, third generation) telephone. This paper describes a potential EM sensor/acoustic based vocoder implementation.
Date: October 25, 2001
Creator: Ng, L C; Holzrichter, J F & Larson, P E
Object Type: Article
System: The UNT Digital Library

Office of Independent Counsel Donald C. Smaltz in re Secretary of Agriculture Alphonso Michael Espy

This is the web site of the Office of Independent Counsel in the investigation and prosecutions involving matters relating to former Secretary of Agriculture, Alphonso Michael Espy. Donald C. Smaltz was appointed Independent Counsel by the Special Division of the United States Court of Appeals for the District of Columbia on September 9, 1994, to "investigate to the maximum extent authorized by [law]" whether Secretary Espy "committed a violation of any federal criminal law . . . relating in any way to the acceptance of gifts by him from organizations or individuals with business pending before the Department of Agriculture." He was also given jurisdiction to investigate "other allegations or evidence of violations of any federal criminal law by organizations or individuals developed during the course of the investigation of Secretary Espy and connected with or arising out of that investigation." The purpose of this web site is to give the public access to public information that defines and explains the investigation.
Date: October 25, 2001
Creator: Office of Independent Counsel Donald C. Smaltz
Object Type: Website
System: The UNT Digital Library
Position Resolution Studies with MSU 32-Fold Segmented HPGe Detector (open access)

Position Resolution Studies with MSU 32-Fold Segmented HPGe Detector

We present position sensitivity measurements obtained with one of the 32-fold segmented HPGe detectors from Michigan State University. These measurements were performed with a collimated beam of {sup 137}Cs gamma rays scattered by 90 degrees. This deposits 374 keV at a given location inside the crystal. A position resolution can be determined over many events by examining the digitally recorded pulse shapes on the 32 electrical contacts. If position resolution is adequate, gamma ray Compton camera imaging may be possible.
Date: October 25, 2001
Creator: Lehner, C E; Vetter, K; Kuhn, A; Schmid, G J; Beckedahl, D A; Blair, J J et al.
Object Type: Article
System: The UNT Digital Library
R-Matrix Evaluation of 160 Neutron Cross Sections up to 6.3 MeV (open access)

R-Matrix Evaluation of 160 Neutron Cross Sections up to 6.3 MeV

We have evaluated {sup 16}O neutron cross sections in the resolved resonance region with the multilevel Reich-Moore code SAMMY. Resonance parameters were determined by a consistent analysis, including both Doppler and resolution broadening effects. To properly treat the {alpha} particle exit channel, an algorithm to calculate charged particle penetrabilities and shifts was incorporated into SAMMY.
Date: October 25, 2001
Creator: Sayer, R.O.
Object Type: Article
System: The UNT Digital Library
Social Security: The Cost-of-Living Adjustment in January 2002 (open access)

Social Security: The Cost-of-Living Adjustment in January 2002

This report discusses the Social Security recipients that receive a costof- living adjustment (COLA) in January of each year. An automatic Social Security benefit increase reflects the rise in the cost of living over roughly a 1-year period
Date: October 25, 2001
Creator: Koitz, David & Kollmann, Geoffrey
Object Type: Report
System: The UNT Digital Library
Social Security: The Cost-of-Living Adjustment in January 2002 (open access)

Social Security: The Cost-of-Living Adjustment in January 2002

None
Date: October 25, 2001
Creator: Koitz, David Stuart; Kollmann, Geoffrey & Sidor, Gary
Object Type: Report
System: The UNT Digital Library
Terrorism Funding: FY2002 Appropriations Bills (open access)

Terrorism Funding: FY2002 Appropriations Bills

None
Date: October 25, 2001
Creator: Nowels, Larry
Object Type: Report
System: The UNT Digital Library
Aviation Security: Vulnerabilities in, and Alternatives for, Preboard Screening Security Operations (open access)

Aviation Security: Vulnerabilities in, and Alternatives for, Preboard Screening Security Operations

Testimony issued by the General Accounting Office with an abstract that begins "A safe and secure civil aviation system is critical to the nation's overall security, physical infrastructure, and economy. Billions of dollars and countless programs and policies have gone into developing such a system. Although many of the specific factors contributing to the terrible events of September 11 are still unclear, it is apparent that our aviation security system is plagued by serious weaknesses that can have devastating consequences. Last year, as part of an undercover investigation, GAO special agents used fake law enforcement badges and credentials to gain access to secure areas at two airports. They were also issued tickets and boarding passes, and could have carried weapons, explosives, or other dangerous items onto the aircraft. GAO tests of airport screeners also found major shortcomings in their ability to detect dangerous items hidden on passengers or in carry-on luggage. These weaknesses have raised questions about the need for alternative approaches. In assessing alternatives, five outcomes should be considered: improving screener performance, establishing accountability, ensuring cooperation among stakeholders, moving people efficiently, and minimizing legal and liability issues."
Date: September 25, 2001
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Comparison of Refractory Performance in Black Liquor Gasifiers and a Smelt Test System (open access)

Comparison of Refractory Performance in Black Liquor Gasifiers and a Smelt Test System

Prior laboratory corrosion studies along with experience at the black liquor gasifier in New Bern, North Carolina, clearly demonstrate that serious material problems exist with the gasifier's refractory lining. Mullite-based and alumina-based refractories used at the New Bern facility suffered significant degradation even though they reportedly performed adequately in smaller scale systems. Oak Ridge National Laboratory's involvement in the failure analysis, and the initial exploration of suitable replacement materials, led to the realization that a simple and reliable, complementary method for refractory screening was needed. The development of a laboratory test system and its suitability for simulating the environment of black liquor gasifiers was undertaken. Identification and characterization of corrosion products were used to evaluate the test system as a rapid screening tool for refractory performance and as a predictor of refractory lifetime. Results from the test systems and pl ants were qualitatively similar.
Date: September 25, 2001
Creator: Peascoe, RA
Object Type: Article
System: The UNT Digital Library
Congressional Resources in CRS Research Centers and the La Follette Congressional Reading Room (open access)

Congressional Resources in CRS Research Centers and the La Follette Congressional Reading Room

This report describes types of CRS products and a selection of the most frequently used printed and online reference sources available in the reading room and research centers for use by congressional staff.
Date: September 25, 2001
Creator: Gerli, Merete F.
Object Type: Report
System: The UNT Digital Library
Congressional Resources in CRS Research Centers and the La Follette Congressional Reading Room (open access)

Congressional Resources in CRS Research Centers and the La Follette Congressional Reading Room

This report describes types of CRS products and a selection of the most frequently used printed and online reference sources available in the reading room and research centers for use by congressional staff. These deal with legislation and public policy; bills, congressional documents, laws, and regulations; Congress, elections, and politics; the federal government; directories of organizations, associations, corporations, state agencies, educational institutions, and the media; biographical information; data on foreign countries and international affairs; quick facts and statistics; and special collections such as quotations.
Date: September 25, 2001
Creator: Gerli, Merete F.
Object Type: Report
System: The UNT Digital Library
Development of Low-cost Hydrogen Sensors (open access)

Development of Low-cost Hydrogen Sensors

This research was aimed at understanding and improving the speed and reproducibility of our resistive hydrogen sensor, along with complementary efforts in manufacturability and further design improvements. Maskworks were designed to allow for the printing and firing of multi-sensor layouts (15 per substrate) and a large batch of these sensors was produced using standard thick-film manufacturing lines. Piece-to-piece variations of both the as-made resistance and the response of these sensors to hydrogen were within acceptable tolerances, and the sensor design has now been released for commercial prototyping. Automated testing was begun in order to develop long-term performance data. Dynamic response of selected sensors was measured before and after exposures to methane, hydrogen sulfide, and carbon monoxide, in order to assess the effects of interference gases and surface poisoning. As expected, H{sub 2}S degrades the sensor somewhat, whereas CH{sub 4} and CO do not create significant interference when air is present.
Date: September 25, 2001
Creator: Lauf, R.J.
Object Type: Report
System: The UNT Digital Library
Development of novel epidermal growth receptor-basedradiopharmaceuticals: Imaging agents for breast cancer (open access)

Development of novel epidermal growth receptor-basedradiopharmaceuticals: Imaging agents for breast cancer

The goal of this research was to develop epidermal growthfactor receptor (EGFR) nuclear medicine breast cancer imaging agents. Ourapproach was to synthesize small molecule inhibitors of the EGFR tyrosinekinase (tk) suitable for labeling with single photon or positron-emittingradioisotopes and evaluate the imaging potential of these new molecules.We have synthesized and fully characterized 22 quinazoline compounds. Allcompounds inhibit EGFR tk phosphorylation activity in the nanomolarrange. All compounds tested exhibited specificity for the EGFR tk versusthe ErbB2 and ErbB4 tyrosine kinases. A radiometric binding assay usingan iodine-125 labeled quinazoline was developed to determine the affinityof the quinazolines for the EGFR tk ATP binding site. The affinitiesranged from 0.4-51 nM. The octanol/water partition coefficients (Log P;lipophilicity) of the new compounds ranged from 2.2-5.5. Six compoundshave been labeled with fluorine-18. Biodistribution in EGFRoverexpressing tumor bearing mice demonstrated tumor uptake buthighlighted delivery and metabolism issues. The 2-fluoro quinazoline wasnot metabolized in an in vitro hepatocyte study. From this work a breadthof agent characteristics was created establishing the foundation forfuture research toward the optimal EGFR imaging agent.
Date: September 25, 2001
Creator: Van Brocklin, Henry F.
Object Type: Report
System: The UNT Digital Library
The DOE National Transportation Program Cost-Estimating Model (open access)

The DOE National Transportation Program Cost-Estimating Model

The United States Department of Energy (DOE) carries out a significant amount of transportation each year, including waste remediation activities at the sites for which it is responsible. In future years, the amount of material transported is expected to increase, and the costs of this transportation are expected to be large. To support the assessment of such costs, a cost-estimating model was developed in 1996, peer-reviewed against other available packaging and transportation cost data, and used to calculate the costs for a significant number of shipping campaigns of radioactive waste. This cost-estimating model, known as the Ten-year Plan Transportation Model (TEPTRAM), served as the cost-estimating model for radioactive material shipments in developing the DOE Office of Environmental Management's Ten Year Plan. The TEPTRAM model considered costs for recovery and processing of the wastes, packaging of the wastes for transport, carriage of the waste and a rough estimate of labor cost s associated with preparing and undertaking the shipments. At the user's direction, the model could also include the cost for DOE's interaction with its external stakeholders (e.g., state and local governments and tribal entities) and the cost associated with tracking and communication (e.g., use of the DOE TRANSCOM system). By …
Date: September 25, 2001
Creator: Rawl, R.R.
Object Type: Article
System: The UNT Digital Library
Effect of Surface Condition and Heat Treatment on Corrosion of Type 316L Stainless Steel in a Mercury Thermal Convection Loop (open access)

Effect of Surface Condition and Heat Treatment on Corrosion of Type 316L Stainless Steel in a Mercury Thermal Convection Loop

Two thermal convection loops (TCLs) fabricated from 316L stainless steel and containing mercury and a variety of 316L coupons representing variable surface conditions and heat treatments have been operated continuously for 2000 h. Surface conditions included surface ground, polished, gold-coated, chemically etched, bombarded with Fe to simulate radiation damage, and oxidized. Heat treatments included solution treated, welded, and sensitized. In addition, a nitrogen doped 316L material, termed 316LN, was also examined in the solution treated condition. Duplicate TCLs were operated in this experiment--both were operated with a 305 C peak temperature, a 65 C temperature gradient, and mercury velocity of 1.2 m/min--but only one included a 36 h soak in Hg at 310 C just prior to operation to encourage wetting. Results indicate that the soak in Hg at 310 C had no lasting effect on wetting or compatibility with Hg. Further, based on examination of post-test wetting and coupon weight loss, only the gold-coated surfaces revealed significant interaction with Hg. In areas wetted significantly by Hg, the extreme surface of the stainless steel (ca 10 {micro}m) was depleted in Ni and Cr compared to the bulk composition.
Date: September 25, 2001
Creator: Pawel, S. J.
Object Type: Report
System: The UNT Digital Library
Enhanced Site Characterization of the 618-4 Burial Ground (open access)

Enhanced Site Characterization of the 618-4 Burial Ground

This report describes the results obtained from deployment of the Enhanced Site Characterization System (ESCS) at the Hanford Site's 618-4 Burial Ground. The objective of this deployment was to use advanced geostatistical methods to integrate and interpret geophysical and ground truth data, to map the physical types of waste materials present in unexcavated portions of the burial ground. One issue of particularly interest was the number of drums (containing depleted uranium metal shavings or uranium-oxide powder) remaining in the burial ground and still requiring removal.Fuzzy adaptive resonance theory (ART), a neural network classification method, was used to cluster the study area into 3 classes based on their geophysical signatures. Multivariate statistical analyses and discriminant function analysis (DFA) indicated that the drum area as well as a second area (the SW anomaly) had similar geophysical signatures that were different from the rest of the burial ground. Further analysis of the drum area suggested that as many as 770 drums to 850 drums may remain in that area. Similarities between the geophysical signatures of the drum area and the SW anomaly suggested that excavation of the SW anomaly area also proceed with caution.Deployment of the ESCS technology was successful in integrating multiple …
Date: September 25, 2001
Creator: Murray, Christopher J.; Last, George V. & Chien, Yi-Ju
Object Type: Report
System: The UNT Digital Library
Enhanced Site Characterization of the 618-4 Burial Ground (open access)

Enhanced Site Characterization of the 618-4 Burial Ground

This report describes the results obtained from deployment of the Enhanced Site Characterization System (ESCS) at the Hanford Site's 618-4 Burial Ground. The objective of this deployment was to use advanced geostatistical methods to integrate and interpret geophysical and ground truth data, to map the physical types of waste materials present in unexcavated portions of the burial ground. One issue of particularly interest was the number of drums (containing depleted uranium metal shavings or uranium-oxide powder) remaining in the burial ground and still requiring removal.Fuzzy adaptive resonance theory (ART), a neural network classification method, was used to cluster the study area into 3 classes based on their geophysical signatures. Multivariate statistical analyses and discriminant function analysis (DFA) indicated that the drum area as well as a second area (the SW anomaly) had similar geophysical signatures that were different from the rest of the burial ground. Further analysis of the drum area suggested that as many as 770 drums to 850 drums may remain in that area. Similarities between the geophysical signatures of the drum area and the SW anomaly suggested that excavation of the SW anomaly area also proceed with caution. Deployment of the ESCS technology was successful in integrating …
Date: September 25, 2001
Creator: Murray, Christopher J; Last, George V & Chien, Yi-Ju
Object Type: Report
System: The UNT Digital Library