States

Improved alternating gradient transport and focusing of neutral molecules (open access)

Improved alternating gradient transport and focusing of neutral molecules

Polar molecules, in strong-field seeking states, can be transported and focused by an alternating sequence of electric field gradients that focus in one transverse direction while defocusing in the other. We show by calculation and numerical simulation, how one may greatly improve the alternating gradient transport and focusing of molecules. We use a new optimized multipole lens design, a FODO lattice beam transport line, and lenses to match the beam transport line to the beam source and the final focus. We derive analytic expressions for the potentials, fields, and gradients that may be used to design these lenses. We describe a simple lens optimization procedure and derive the equations of motion for tracking molecules through a beam transport line. As an example, we model a straight beamline that transports a 560 m/s jet-source beam of methyl fluoride molecules 15 m from its source and focuses it to 2 mm diameter. We calculate the beam transport line acceptance and transmission, for a beam with velocity spread, and estimate the transmitted intensity for specified source conditions. Possible applications are discussed.
Date: December 2, 2001
Creator: Kalnins, Juris; Lambertson, Glen & Gould, Harvey
Object Type: Article
System: The UNT Digital Library
LDA+DMFT Approach to Materials with Strong Electronic Correlations (open access)

LDA+DMFT Approach to Materials with Strong Electronic Correlations

LDA+DMFT is a novel computational technique for ab initio investigations of real materials with strongly correlated electrons, such as transition metals and their oxides. It combines the strength of conventional band structure theory in the local density approximation (LDA) with a modern many-body approach, the dynamical mean-field theory (DMFT). In the last few years LDA+DMFT has proved to be a powerful tool for the realistic modeling of strongly correlated electronic systems. In this paper the basic ideas and the set-up of the LDA+DMFT(X) approach, where X is the method used to solve the DMFT equations, are discussed. Results obtained with X=QMC (quantum Monte Carlo) and X=NCA (non-crossing approximation) are presented and compared. By means of the model system La{sub 1-x}Sr{sub x}TiO{sub 3} we show that the method X matters qualitatively and quantitatively. Furthermore, they discuss recent results on the Mott-Hubbard metal-insulator transition in the transition metal oxide V{sub 2}O{sub 3} and the {alpha}-{gamma} transition in the 4f-electron system Ce.
Date: December 2, 2001
Creator: Held, K.; Nekrasov, I. A.; Keller, G.; Eyert, V.; Blumer, N.; McMahan, A. K. et al.
Object Type: Article
System: The UNT Digital Library
Benchmarking residual dose rates in a NuMI-like environment (open access)

Benchmarking residual dose rates in a NuMI-like environment

Activation of various structural and shielding materials is an important issue for many applications. A model developed recently to calculate residual activity of arbitrary composite materials for arbitrary irradiation and cooling times is presented in the paper. Measurements have been performed at the Fermi National Accelerator Laboratory using a 120 GeV proton beam to study induced radioactivation of materials used for beam line components and shielding. The calculated residual dose rates for the samples studied behind the target and outside of the thick shielding are presented and compared with the measured ones. Effects of energy spectra, sample material and dimensions, their distance from the shielding, and gaps between the shielding modules and walls as well as between the modules themselves were studied in detail.
Date: November 2, 2001
Creator: al., Igor L. Rakhno et
Object Type: Article
System: The UNT Digital Library
The CDF computing and analysis system: First experience (open access)

The CDF computing and analysis system: First experience

The Collider Detector at Fermilab (CDF) collaboration records and analyses proton anti-proton interactions with a center-of-mass energy of 2 TeV at the Tevatron. A new collider run, Run II, of the Tevatron started in April. During its more than two year duration the CDF experiment expects to record about 1 PetaByte of data. With its multi-purpose detector and center-of-mass energy at the frontier, the experimental program is large and versatile. The over 500 scientists of CDF will engage in searches for new particles, like the Higgs boson or supersymmetric particles, precision measurement of electroweak parameters, like the mass of the W boson, measurement of top quark parameters, and a large spectrum of B physics. The experiment has taken data and analyzed them in previous runs. For Run II, however, the computing model was changed to incorporate new methodologies, the file format switched, and both data handling and analysis system redesigned to cope with the increased demands. This paper (4-036 at Chep 2001) gives an overview of the CDF Run II compute system with emphasis on areas where the current system does not match initial estimates and projections. For the data handling and analysis system a more detailed description is given.
Date: November 2, 2001
Creator: al., R. Colombo et
Object Type: Article
System: The UNT Digital Library
The CDF online silicon vertex tracker (open access)

The CDF online silicon vertex tracker

The CDF Online Silicon Vertex Tracker reconstructs 2-D tracks by linking hit positions measured by the Silicon Vertex Detector to the Central Outer Chamber tracks found by the eXtremely Fast Tracker. The system has been completely built and assembled and it is now being commissioned using the first CDF run II data. The precision measurement of the track impact parameter will allow triggering on B hadron decay vertices and thus investigating important areas in the B sector, like CP violation and B{sub s} mixing. In this paper we briefly review the architecture and the tracking algorithms implemented in the SVT and we report on the performance of the system achieved in the early phase of CDF run II.
Date: November 2, 2001
Creator: al., W. Ashmanskas et
Object Type: Article
System: The UNT Digital Library
The CDF Run II disk inventory manager (open access)

The CDF Run II disk inventory manager

The Collider Detector at Fermilab (CDF) experiment records and analyses proton-antiproton interactions at a center-of-mass energy of 2 TeV. Run II of the Fermilab Tevatron started in April of this year. The duration of the run is expected to be over two years. One of the main data handling strategies of CDF for Run II is to hide all tape access from the user and to facilitate sharing of data and thus disk space. A disk inventory manager was designed and developed over the past years to keep track of the data on disk, to coordinate user access to the data, and to stage data back from tape to disk as needed. The CDF Run II disk inventory manager consists of a server process, a user and administrator command line interfaces, and a library with the routines of the client API. Data are managed in filesets which are groups of one or more files. The system keeps track of user access to the filesets and attempts to keep frequently accessed data on disk. Data that are not on disk are automatically staged back from tape as needed. For CDF the main staging method is based on the mt-tools package as …
Date: November 2, 2001
Creator: Lammel, Paul Hubbard and Stephan
Object Type: Article
System: The UNT Digital Library
Drug Control: International Policy and Options (open access)

Drug Control: International Policy and Options

Over the past decade, worldwide production of illicit drugs has risen dramatically: opium and marijuana production has roughly doubled and coca production tripled. Street prices of cocaine and heroin have fallen significantly in the past 20 years, reflecting increased availability. Despite apparent national political resolve to deal with the drug problem, inherent contradictions regularly appear between U.S. anti-drug policy and other national policy goals and concerns. The mix of competing domestic and international pressures and priorities has produced an ongoing series of disputes within and between the legislative and executive branches concerning U.S. international drug policy. One contentious issue has been the Congressionally-mandated certification process, an instrument designed to induce specified drug-exporting countries to prioritize or pay more attention to the fight against narcotics businesses.
Date: November 2, 2001
Creator: Perl, Raphael F.
Object Type: Report
System: The UNT Digital Library
A Fast and Accurate Position Sensitive Timing Detector for Charged Particles (open access)

A Fast and Accurate Position Sensitive Timing Detector for Charged Particles

A position-sensitive timing detector suitable for detection of low-energy heavy ions is described. The device is based on the detection of secondary electrons emitted following ion impact on a surface. Using a combination of magnetic and electric fields these devices can deliver sub-nanosecond time definition and sub-millimeter position information for ion impact. When choosing a thin foil for the surface intercepting the heavy ion trajectory, multiple detectors can be used and reliable tracking of heavy ions with moderate energies ({ge} 1MeV/A) becomes feasible.
Date: November 2, 2001
Creator: Shapira, D.
Object Type: Article
System: The UNT Digital Library
Financial Management: Improper Payments Reported in Fiscal Year 2000 Financial Statements (open access)

Financial Management: Improper Payments Reported in Fiscal Year 2000 Financial Statements

Correspondence issued by the General Accounting Office with an abstract that begins "This report provides information on improper payments that federal agencies reported in their fiscal year 2000 financial statements. GAO found that the amount of improper payments reported in agency financial statements has remained consistent at about $20 billion for the past three years. Even though these amounts are substantial, agency-specific audits and studies indicate the improper payment problem is much more widespread than disclosed in agency financial statement reports. The President's Management Agenda for Fiscal Year 2002 has made the reduction of improper payments a priority. The Administration has taken steps to require federal agencies to identify erroneous payments and to discuss planned actions to better manage these payments."
Date: November 2, 2001
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
GEM-type detectors using LIGA and etchable glass technologies (open access)

GEM-type detectors using LIGA and etchable glass technologies

Gas electron multipliers (GEMS) have been made by a deep X-ray lithography technique (LIGA process) using synchrotron radiation on polymethylmethacrylate (PMMA) and by UV processes using a UV etchable glass. Gain, stability and rate capability for these detectors are described.The LIGA detectors described consist of PMMA sheets of various thicknesses, 125mm to 350mm, and have 150mm x 150mm square holes spaced with a pitch of 300mm. Thin copper electrodes are plated on the top and bottom surfaces using a Damascene method, followed by electroless plating of the copper onto a palladium-tin base layer. For various thicknesses of PMMA measurements have been made of absolute gain vs. voltage, time stability of gain, and rate capability. The operating gas mixture was usually Ar/CO2 (70/30) gas, but some tests were also done using P10 gas. We also made GEM-like detectors using the UV etchable glass called Foturan, patterned by exposure to UV light and subsequent etching. A few measurements using these detectors will be reported, including avalanche gain and time stability.
Date: November 2, 2001
Creator: Ahn, S. K.; Kim, J. G.; Perez-Mendez, V.; Chang, S.; Jackson, K. H.; Kadyk, J. A. et al.
Object Type: Article
System: The UNT Digital Library
Improved process control through real-time measurement of mineral content (open access)

Improved process control through real-time measurement of mineral content

In a highly collaborative research and development project with mining and university partners, sensors and data-analysis tools are being developed for rock-mass characterization and real-time measurement of mineral content. Determining mineralogy prior to mucking in an open-pit mine is important for routing the material to the appropriate processing stream. A possible alternative to lab assay of dust and cuttings obtained from drill holes is continuous on-line sampling and real-time x-ray fluorescence (XRF) spectroscopy. Results presented demonstrate that statistical analyses combined with XRF data can be employed to identify minerals and, possibly, different rock types. The objective is to create a detailed three-dimensional mineralogical map in real time that would improve downstream process efficiency.
Date: November 2, 2001
Creator: Turler, Daniel; Karaca, Murat; Davis, William B.; Giauque, Robert D. & Hopkins, Deborah
Object Type: Article
System: The UNT Digital Library
Indian Issues: Improvements Needed in Tribal Recognition Process (open access)

Indian Issues: Improvements Needed in Tribal Recognition Process

A letter report issued by the General Accounting Office with an abstract that begins "The Indian gambling industry has flourished since the enactment of the Indian Gaming Regulatory Act in 1988. Nearly 200 tribes generated about $10 billion in annual revenues in 1999 from their gambling operations. Because of weaknesses in the federal recognition process, the basis for tribal recognition decisions by the Bureau of Indian Affairs (BIA) is not always clear and the length of time involved can be substantial. Despite an increasing workload, the number of BIA staff assigned to evaluate the petitions has fallen by about 35 percent since 1993. Just as important, the process lacks effective procedures for promptly addressing the increased workload. In particular, the process does not impose effective deadlines that create a sense of urgency, and procedures for providing information to interested third parties are ineffective. GAO summarized this report in testimony before Congress; see: Indian Issues: More Consistent and Timely Tribal Recognition Process Needed, by Barry T. Hill, Director for Natural Resources and Environment, before the Subcommittee on Energy Policy, Natural Resources and Regulatory Affairs, House Committee on Government Reform. GAO-01-415T, Feb. 7 (nine pages)."
Date: November 2, 2001
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Means-Tested Programs: Determining Financial Eligibility Is Cumbersome and Can Be Simplified (open access)

Means-Tested Programs: Determining Financial Eligibility Is Cumbersome and Can Be Simplified

A letter report issued by the General Accounting Office with an abstract that begins "About 80 means-tested federal programs assisted low-income people in 1998. GAO reviewed 11 programs that assisted families and individuals with income, food, medical assistance, and housing. Despite substantial overlap in the populations they serve, the 11 programs varied significantly in their financial eligibility rules. At the most basic level, the dollar levels of the income limits--the maximum amounts of income an applicant can have and still be eligible for a program--vary across programs. Beyond this, differences exist in the income rules, such as whose income and what types of income are counted. The variations and complexity of the federal financial eligibility rules, along with other factors, have led to processes that are often duplicative and cumbersome for both caseworkers and applicants. Overall, federal, state, and local entities have made little progress in simplifying or coordinating eligibility determination processes. States realigned some of the financial rules, but only to a limited extent. Another approach uses computer systems to establish joint eligibility determination processes that a single caseworker can administer. Efforts to simplify or better coordinate eligibility determination processes confront many obstacles, including restrictive federal program statutes and …
Date: November 2, 2001
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
PDF Uncertainties in WH Production at Tevatron (open access)

PDF Uncertainties in WH Production at Tevatron

We apply a method proposed by members of CTEQ Collaboration to estimate the uncertainty in associated W-Higgs boson production at Run II of the Tevatron due to our imprecise knowledge of parton distribution functions. We find that the PDF uncertainties for the signal and background rates are of the order 3%. The PDF uncertainties for the important statistical quantities (significance of the Higgs boson discovery, accuracy of the measurement of the WH cross section) are smaller (1.5%) due to the strong correlation of the signal and background.
Date: November 2, 2001
Creator: Sullivan, P. M. Nadolsky and Z.
Object Type: Article
System: The UNT Digital Library
Preliminary results of a PWA of the centrally produced {phi}{phi} system (open access)

Preliminary results of a PWA of the centrally produced {phi}{phi} system

The authors present preliminary results of a Partial Wave Analysis of the centrally produced {phi}{phi} system at 800 GeV/c in the reaction pp {yields} p{sub slow} ({phi}{phi})p{sub fast}. The preliminary results with one and two M = 0 waves, indicate that most of the cross section can be described by two waves, with J{sup PC} LS{sup {eta}} = 2{sup 2}02{sup -1}, 0{sup 2}00{sup -1}.
Date: November 2, 2001
Creator: al., Marco A. Reyes et
Object Type: Article
System: The UNT Digital Library
Radiation sources and diagnostics with ultrashort electron bunches (open access)

Radiation sources and diagnostics with ultrashort electron bunches

The basic principles and design of radiation sources (transition radiation, Cerenkov radiation, radiation from periodic structures, etc.) and radiation-based diagnostics will be discussed, with emphasis on radiation from ultra-short electron bunches. Ultra-short electron bunches have the potential to produce high peak flux radiation sources that cover wavelength regimes where sources are currently not widely available (coherent THz/IR) as well as ultrashort X-ray pulses (3-100 fs). While radiation from the electron bunch contains the full signature of the electron beam and/or medium it has travelled through, the deconvolution of a single property of interest can be difficult due to a large number of contributing properties. The experimental implementation of novel solutions to this problem will be described for beams from 30 MeV to 30 GeV, including fluctuational interferometry, source imaging, phase matched cone angles and laser-based techniques, which utilize optical transition radiation, wiggler and Cerenkov radiation, and Thomson scattering. These novel diagnostic methods have the potential to resolve fs bunch durations, slice emittance on fs scales, etc. The advantages and novel features of these techniques will be discussed.
Date: November 2, 2001
Creator: Catravas, P.; Esarey, E. & Leemans, W. P.
Object Type: Article
System: The UNT Digital Library
Spectral Properties of Americium(III) in Silicate Matrices: Concentration-Dependent Up-Conversion Emission (open access)

Spectral Properties of Americium(III) in Silicate Matrices: Concentration-Dependent Up-Conversion Emission

We have been pursuing the spectroscopic properties of actinide ions in silicate matrices. One facet of these studies involves the behavior of Stokes and anti-Stokes emissions exhibited by Am'' in these hosts. Several attributes have been found to influence the spectral profile, which include excitation wavelength, laser power, and dopant-concentration. Excitation with the 514.5 nm (19435 cm{sup -1}) line of argon laser provides anti-Stokes emissions at 21100 and -19920 cm{sup -1} in the boro-silicate matrices. This up-conversion was found to proceed through a multi-photon scheme, and its' efficiency increases with increased dopant concentration. Based on our concentration-dependent studies, the up-conversion is suggested to involve a cross-relaxation process [({sup 5}D{sub 1}, {sup 7}F{sub 0}{sup 7}F{sub 6}, {sup 7}F{sub 2})] between neighboring americium ions.
Date: November 2, 2001
Creator: Assefa, Z.
Object Type: Article
System: The UNT Digital Library
State Department and Related Agencies: FY2002 Appropriations (open access)

State Department and Related Agencies: FY2002 Appropriations

None
Date: November 2, 2001
Creator: Epstein, Susan B.
Object Type: Report
System: The UNT Digital Library
Tagging of Isobars Using Energy Loss and Time-of-flight Measurements (open access)

Tagging of Isobars Using Energy Loss and Time-of-flight Measurements

The technique for tagging isobars in a mixed beam by measuring energy loss by time-of-flight has been tested. With this method, isobar separation should improve by allowing more energy loss (thicker absorber), but only if one can control absorber homogeneity. Measurements of beam energy toss and energy spread obtained under such conditions were shown to be close to predicted values using both collisional and charge exchange contributions to energy straggling. The calculation of energy straggling allows us to study the efficacy of this method for isobar separation when applied to different mass ranges and beam energies. Separation in a most difficult case, an analyzed beam of A = 132 isobars at energies near 3 MeV/A has been demonstrated. The time-of-flight information can be added on line as an additional tag to the data stream for events of interest. Such event by event tagging enables one to study the effect of differences in isobaric mixture in the beam on the reaction outcome even when isobar separation is not complete.
Date: November 2, 2001
Creator: Shapira, D.
Object Type: Article
System: The UNT Digital Library
Terrorism, the Future, and U.S. Foreign Policy (open access)

Terrorism, the Future, and U.S. Foreign Policy

None
Date: November 2, 2001
Creator: Perl, Raphael F.
Object Type: Report
System: The UNT Digital Library
Texas Register, Volume 26, Number 44, Pages 8597-8916, November 2, 2001 (open access)

Texas Register, Volume 26, Number 44, Pages 8597-8916, November 2, 2001

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.
Date: November 2, 2001
Creator: Texas. Secretary of State.
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History
A two-level fanout system for the CDF silicon vertex tracker (open access)

A two-level fanout system for the CDF silicon vertex tracker

The Fanout system is part of the Silicon Vertex Tracker, a new trigger processor designed to reconstruct charged particle trajectories at Level 2 of the CDF trigger, with a latency of 10 {micro}s and an event rate up to 100 kHz. The core of SVT is organized as 12 identical slices, which process in parallel the data from the 12 independent azimuthal wedges of the Silicon Vertex Detector (SVXII). Each SVT slice links the digitized pulse heights found within one SVXII wedge to the tracks reconstructed by the Level 1 fast track finder (XFT) in the corresponding 30{sup o} angular region of the Central Outer Tracker. Since the XFT tracks are transmitted to SVT as a single data stream, their distribution to the proper SVT slices requires dedicated fanout logic. The Fanout system has been implemented as a multi-board project running on a common 20 MHz clock. Track fanout is performed in two steps by one ''Fanout A'' and two ''Fanout B'' boards. The architecture, design, and implementation of this system are described.
Date: November 2, 2001
Creator: al., A. Bardi et
Object Type: Article
System: The UNT Digital Library
Vibrational Raman and Optical Studies of Cm in Zirconia-Based Pyrochlores and Related Oxides Matrices (open access)

Vibrational Raman and Optical Studies of Cm in Zirconia-Based Pyrochlores and Related Oxides Matrices

Raman spectroscopy has been employed to follow the phase behavior of Cm-Zr oxide materials as a function of Cm:Zr ratio. Three different structural phases, monoclinic, cubic and pyrochlore, are formed when the Cm:Zr ratio is varied from >0 to 1. Each phase produces a distinct Raman profile in the 100-700 cm{sup -1} spectral region. Up to 10 atom % Cm, the Raman spectra indicate that the monoclinic structure is dominant. Raman bands corresponding to the monoclinic phase are absent in samples containing 20 - 40 atom % Cm. Concomitantly, a band at -600 cm' broadens and increases in intensity with increasing curium content, indicating that the cubic phase is dominant in this concentration range. The pyrochlore oxide structure, which forms at 50 atom % Cm, generates three Raman bands (the center of mass are at 283, 387,495 cm-') out of six bands predicted by nuclear site group analyses. The strongest of these is at 283 cm-', and corresponds to the O-Cm-O bending mode. Details of these studies will be compared and discussed with data obtained for comparable systems containing selected analogous 4f-elements.
Date: November 2, 2001
Creator: Assefa, Z.
Object Type: Article
System: The UNT Digital Library
Young physicists' forum (open access)

Young physicists' forum

The Young Physicists' Forum was an opportunity for the younger members of the particle-physics community to gather at Snowmass 2001 and to study and debate major issues that face the field over the next twenty years. Discussions were organized around three major topics: outreach and education, the impact of globalization, and building a robust and balanced field. We report on the results of these discussions, as presented on July 17, 2001.
Date: November 2, 2001
Creator: al., T. Adams et
Object Type: Article
System: The UNT Digital Library