3-D electromagnetic modeling of wakefields in accelerator components (open access)

3-D electromagnetic modeling of wakefields in accelerator components

We discuss the use of 3-D finite-difference time-domain (FDTD) electromagnetic codes for modeling accelerator components. Computational modeling of cylindrically symmetric structures such as induction accelerator cells has been very successful in predicting the wake potential and wake impedances of these structures, but full 3-D modeling of complex structures has been limited due to substantial computer resources required for a full 3-D model. New massively parallel 3-D time domain electromagnetic codes now under development using conforming unstructured meshes allow a substantial increase in the geometric fidelity of the structures being modeled. Development of these new codes are discussed in context of applicability to accelerator problems. Various 3-D structures are tested with an existing cubical cell FDTD code and wake impedances compared with simple analytic models for the structures; results will be used as benchmarks for testing the new time time domain codes. Structures under consideration include a stripline beam position monitor as well as circular and elliptical apertures in circular waveguides. Excellent agreement for monopole and dipole impedances with models were found for these structures below the cutoff frequency of the beam line.
Date: September 18, 1996
Creator: Poole, B.R.; Caporaso, G.J.; Ng, Wang C.; Shang, C.C. & Steich, D.
System: The UNT Digital Library
2007 Archaea: Ecology, Metabolism and Molecular Biology (open access)

2007 Archaea: Ecology, Metabolism and Molecular Biology

The Archaea are a fascinating and diverse group of prokaryotic organisms with deep roots overlapping those of eukaryotes. The focus of this GRC conference, 'Archaea: Ecology Metabolism & Molecular Biology', expands on a number of emerging topics highlighting the evolution and composition of microbial communities and novel archaeal species, their impact on the environment, archaeal metabolism, and research that stems from sequence analysis of archaeal genomes. The strength of this conference lies in its ability to couple reputable areas with new scientific topics in an atmosphere of stimulating exchange. This conference remains an excellent opportunity for younger scientists to interact with world experts in this field.
Date: September 18, 2008
Creator: Gray, Imke Schroeder Nancy Ryan
System: The UNT Digital Library
AB INITIO molecular orbital studies of some high temperature metal halide complexes. [300/sup 0/--500/sup 0/C] (open access)

AB INITIO molecular orbital studies of some high temperature metal halide complexes. [300/sup 0/--500/sup 0/C]

The use of ab initio molecular orbital calculations to aid in the characterization, i.e., structures and energies, of metal halide complexes present in high temperature salt vapors has been investigated. Standard LCAO-SCF methods were used and calculations were carried out using the minimal STO-3G basis set. The complexes included in this study were Al/sub 2/F/sub 6/, Al/sub 2/Cl/sub 6/, AlF/sub 3/ NH/sub 3/, AlCl/sub 3/ NH/sub 3/, and AlF/sub 3/ N/sub 2/. The Al/sub 2/X/sub 6/ complexes are found to have D/sub 2h/ symmetry in agreement with most experimental results. A planar form was found to be considerably higher in energy. The AlX/sub 3/ NH/sub 3/ complexes are found to have C/sub 3v/ symmetry with a small barrier to rotation about the Al-N axis. The AlF/sub 3/ N/sub 2/ complex is found to be weakly bound together with a binding energy of -8.2 kcal/mole at the STO-3G level.
Date: September 18, 1978
Creator: Curtiss, L.A.
System: The UNT Digital Library
The Accelerated Site Technology Deployment Program/Segmented Gate System Project (open access)

The Accelerated Site Technology Deployment Program/Segmented Gate System Project

The Department of Energy (DOE) is working to accelerate the acceptance and application of innovative technologies that improve the way the nation manages its environmental remediation problems. The DOE Office of Science and Technology established the Accelerated Site Technology Deployment Program (ASTD) to help accelerate the acceptance and implementation of new and innovative soil and ground water remediation technologies. Coordinated by the Department of Energy's Idaho Office, the ASTD Program reduces many of the classic barriers to the deployment of new technologies by involving government, industry, and regulatory agencies in the assessment, implementation, and validation of innovative technologies. Funding is provided through the ASTD Program to assist participating site managers in implementing innovative technologies. The program provides technical assistance to the participating DOE sites by coordinating DOE, industry, and regulatory participation in each project; providing finds for optimizing full-scale operating parameters; coordinating technology performance monitoring; and by developing cost and performance reports on the technology applications.
Date: September 18, 2000
Creator: PATTESON,RAYMOND
System: The UNT Digital Library
Advanced Adaptive Optics Technology Development (open access)

Advanced Adaptive Optics Technology Development

The NSF Center for Adaptive Optics (CfAO) is supporting research on advanced adaptive optics technologies. CfAO research activities include development and characterization of micro-electro-mechanical systems (MEMS) deformable mirror (DM) technology, as well as development and characterization of high-resolution adaptive optics systems using liquid crystal (LC) spatial light modulator (SLM) technology. This paper presents an overview of the CfAO advanced adaptive optics technology development activities including current status and future plans.
Date: September 18, 2001
Creator: Olivier, S.
System: The UNT Digital Library
Aerial Neutron Detection of Cosmic-Ray Interactions with the Earth's Surface (open access)

Aerial Neutron Detection of Cosmic-Ray Interactions with the Earth's Surface

We have demonstrated the ability to measure the neutron flux produced by the cosmic-ray interaction with nuclei in the ground surface using aerial neutron detection. High energy cosmic-rays (primarily muons with GeV energies) interact with the nuclei in the ground surface and produce energetic neutrons via spallation. At the air-surface interface, the neutrons produced by spallation will either scatter within the surface material, become thermalized and reabsorbed, or be emitted into the air. The mean free path of energetic neutrons in air can be hundreds of feet as opposed to a few feet in dense materials. As such, the flux of neutrons escaping into the air provides a measure of the surface nuclei composition. It has been demonstrated that this effect can be measured at long range using neutron detectors on low flying helicopters. Radiological survey measurements conducted at Government Wash in Las Vegas, Nevada, have shown that the neutron background from the cosmic-soil interactions is repeatable and directly correlated to the geological data. Government Wash has a very unique geology, spanning a wide variety of nuclide mixtures and formations. The results of the preliminary measurements are presented.
Date: September 18, 2008
Creator: Maurer, Richard
System: The UNT Digital Library
Age of substitutability: or what do we do when the mercury runs out (open access)

Age of substitutability: or what do we do when the mercury runs out

None
Date: September 18, 1975
Creator: Goeller, H.E. & Weinberg, A.M.
System: The UNT Digital Library
Analysis of the numerical effects of parallelism on a parallel genetic algorithm (open access)

Analysis of the numerical effects of parallelism on a parallel genetic algorithm

This paper examines the effects of relaxed synchronization on both the numerical and parallel efficiency of parallel genetic algorithms (GAs). We describe a coarse-grain geographically structured parallel genetic algorithm. Our experiments show that asynchronous versions of these algorithms have a lower run time than-synchronous GAs. Furthermore, we demonstrate that this improvement in performance is partly due to the fact that the numerical efficiency of the asynchronous genetic algorithm is better than the synchronous genetic algorithm. Our analysis includes a critique of the utility of traditional parallel performance measures for parallel GAs, and we evaluate the claims made by several researchers that parallel GAs can have superlinear speedup.
Date: September 18, 1995
Creator: Hart, W. E.; Belew, R. K.; Kohn, S. & Baden, S.
System: The UNT Digital Library
Automated facility for analysis of soil samples by neutron activation, counting, and data control (open access)

Automated facility for analysis of soil samples by neutron activation, counting, and data control

An automated facility remotely and automatically analyzes soil, water, and sediment samples for uranium. The samples travel through pneumatic tubes and switches to be first irradiated by neutrons and then counted for resulting neutron and gamma emission. Samples are loaded into special carriers, or rabbits, which are then automatically loaded into the pneumatic transfer system. The sample carriers have been previously coded with an identification number, which can be automatically read in the system. This number is used for correlating and filing data about the samples. The transfer system, counters, and identification system are controlled by a network of microprocessors. A master microprocessor initiates routines in other microprocessors assigned to specific tasks. The software in the microprocessors is unique for this type of application and lends flexibility to the system.
Date: September 18, 1978
Creator: Voegele, A.L.; Jesse, R.H.; Russell, W.L. & Baker, J.
System: The UNT Digital Library
Availability of enriched stable isotopes: present status and future prospects (open access)

Availability of enriched stable isotopes: present status and future prospects

The Electromagnetic Isotope Enrichment Facility (EMIEF) is currently used to produce 225 enriched stable isotopes of 50 elements. Among these are included most of the known elements with stable isotopes except for the noble gases, certain light elements, monisotopic elements, etc. The EMIEF can also be used to produce enriched samples of radioactive species, most notably the isotopes of uranium and plutonium. These enriched materials are placed in either the Sales Inventory of in the Research Materials Collection (RMC). The materials in the Sales Inventory are for sale to anyone on a first come, first served basis. Prices in the most recent catalog range from $0.05/mg for 99.8% /sup 140/Ce to $1,267/mg for 98.5% /sup 176/Lu. The materials in the RMC are made available to US researchers (or groups that include a US investigator) on a loan basis for use in non-destructive experiments and applications. In addition, certain samples have been provided to European investigators for cross-section studies through the auspices of EURATOM and the European-American Nuclear Data Committee. The status of the enriched isotopes included in the Sales Inventory is tabulated where isotopes are listed that are either not available or are in insufficient quantity or quality to meet …
Date: September 18, 1986
Creator: Hoff, R.W.
System: The UNT Digital Library
B, Lambda{sub b} and charm results from the Tevatron (open access)

B, Lambda{sub b} and charm results from the Tevatron

Recent results on B{sub d}, B{sub u}{sup {+-}}, B{sub s}, {Lambda}{sub b} and Charm hadrons are reported from {approx} 75 pb{sup -1} and {approx} 40 pb{sup -1} of data accumulated at the upgraded CDF and D0 experiments at the Fermilab Tevatron {bar p}-p collider, during Run-II. These include lifetime and mass measurements of B and Charm hadrons, searches for rare decays in charm and B hadrons and CP-violation in Charm decays. Results relevant to CP-violation in B-decays are also reported.
Date: September 18, 2003
Creator: Azfar, F.
System: The UNT Digital Library
Benchmarking EUV mask inspection beyond 0.25 NA (open access)

Benchmarking EUV mask inspection beyond 0.25 NA

The SEMATECH Berkeley Actinic Inspection Tool (AIT) is an EUV-wavelength mask inspection microscope designed for direct aerial image measurements, and pre-commercial EUV mask research. Operating on a synchrotron bending magnet beamline, the AIT uses an off-axis Fresnel zoneplate lens to project a high-magnification EUV image directly onto a CCD camera. We present the results of recent system upgrades that have improved the imaging resolution, illumination uniformity, and partial coherence. Benchmarking tests show image contrast above 75% for 100-nm mask features, and significant improvements and across the full range of measured sizes. The zoneplate lens has been replaced by an array of user-selectable zoneplates with higher magnification and NA values up to 0.0875, emulating the spatial resolution of a 0.35-NA 4 x EUV stepper. Illumination uniformity is above 90% for mask areas 2-{micro}m-wide and smaller. An angle-scanning mirror reduces the high coherence of the synchrotron beamline light source giving measured {sigma} values of approximately 0.125 at 0.0875 NA.
Date: September 18, 2008
Creator: Goldberg, Kenneth A.; Mochi, Iacopo; Anderson, Erik H.; Rekawa, Seno B.; Kemp, Charles D.; Huh, S. et al.
System: The UNT Digital Library
Bunched Beam Stochastic Cooling Project for RHIC. (open access)

Bunched Beam Stochastic Cooling Project for RHIC.

The main performance limitation for RHIC is emittance growth caused by IntraBeam Scattering during the store. We have developed a longitudinal bunched-beam stochastic cooling system in the 5-8 GHz band which will be used to counteract IBS longitudinal emittance growth and prevent de-bunching during the store. Solutions to the technical problems of achieving sufficient kicker voltage and overcoming the electronic saturation effects caused by coherent components within the Schottky spectrum are described. Results from tests with copper ions in RHIC during the FY05 physics run, including the observation of signal suppression, are presented.
Date: September 18, 2005
Creator: Brennan, J. M. & Baskiewicz, M. M.
System: The UNT Digital Library
Cellular senescence as a tumor suppressor mechanism (open access)

Cellular senescence as a tumor suppressor mechanism

None
Date: September 18, 2001
Creator: Campisi, Judith
System: The UNT Digital Library
Ceramic Hot Gas Filter with Integrated Failsafe System (open access)

Ceramic Hot Gas Filter with Integrated Failsafe System

In order to integrate a failsafe system and to improve the cleaning intensity a new cleaning method was recently developed, the CPP (coupled pressure pulse) cleaning (Heidenreich et al. 2001). For the CPP method the cleaning system is directly coupled with the filter candles. One feature of this new technique is that the cleaning gas pressure exceeds the system pressure only by 0.05 to 0.1 MPa, whereas in case of conventional jet pulse systems two times the system pressure (at least 0.6 MPa) is standard. The key advantage of the coupled pressure pulse cleaning is that a safety filter for each filter candle can be integrated in the clean gas side of the filter. Thus, a candle failure is not longer a serious problem. The integrated safety filter enables the operation of the filter system also in case a filter candle breaks. This increases the availability of the filter and prevents an unscheduled costly shut-down of the system. In this paper the design of the ceramic filter wit h the failsafe system and the CPP cleaning will be described. The new developed safety filter elements, their pressure drop and their filtration and clogging behavior will be shown. Tests of single …
Date: September 18, 2002
Creator: Heidenreich, S.; Haag, W.; Walch, A.; Scheibner, B.; Mai, R.; Leibold, H. et al.
System: The UNT Digital Library
Collective Space-Charge Phenomena in the Source Region (open access)

Collective Space-Charge Phenomena in the Source Region

For many devices space-charge-dominated behavior, including the excitation of space-charge collective modes, can occur in the source region, even when the downstream characteristics are not space-charge-dominated. Furthermore, these modes can remain undamped for many focusing periods. Traditional studies of the source region in particle beam systems have emphasized the behavior of averaged beam characteristics, such as total current, rms beam size, or emittance, rather than the details of the full beam distribution function that are necessary to predict the excitation of collective modes. A primary tool for understanding the detailed evolution of a space-charge dominated beam in the source region has been the use of simulation in concert with detailed experimental measurement. However, ''first-principle'' simulations beginning from the emitter surface have often displayed substantial differences from what is measured. This is believed to result from sensitivities in the beam dynamics to small changes in the mechanical characteristics of the gun structure, as well as to similar sensitivities in the numerical methods. Simulations of the beam in the source region using the particle-in-cell WARP code and comparisons to experimental measurements at the University of Maryland are presented to illustrate the complexity in beam characteristics that can occur in the source region. …
Date: September 18, 2004
Creator: Haber, I.; Bernal, S.; Celata, C. M.; Friedman, A.; Grote, D. P.; Kishek, R. A. et al.
System: The UNT Digital Library
Constitutive Model Development for Predicting Thermal Mechanical Fatigue Deformation in Solder Interconnects (open access)

Constitutive Model Development for Predicting Thermal Mechanical Fatigue Deformation in Solder Interconnects

None
Date: September 18, 2000
Creator: VIANCO,PAUL T.; NEILSEN,MICHAEL K.; FOSSUM,ARLO F. & BURCHETT,STEVEN N.
System: The UNT Digital Library
Cooling Force Measurements in Celsius. (open access)

Cooling Force Measurements in Celsius.

The design of future high energy coolers relies heavily on extending the results of cooling force measurements into new regimes by using simulation codes. In order to carefully benchmark these codes we have accurately measured the longitudinal friction force in CELSIUS by recording the phase shift between the beam and the RF voltage while varying the RF frequency. Moreover, parameter dependencies on the electron current, solenoid magnetic field and magnetic field alignment were carried out.
Date: September 18, 2005
Creator: Galnander, B.; Fedotov, A. V.; Litvinenko, V. N. & Al., Et
System: The UNT Digital Library
Coscheduling Technique for Symmetric Multiprocessor Clusters (open access)

Coscheduling Technique for Symmetric Multiprocessor Clusters

Coscheduling is essential for obtaining good performance in a time-shared symmetric multiprocessor (SMP) cluster environment. However, the most common technique, gang scheduling, has limitations such as poor scalability and vulnerability to faults mainly due to explicit synchronization between its components. A decentralized approach called dynamic coscheduling (DCS) has been shown to be effective for network of workstations (NOW), but this technique is not suitable for the workloads on a very large SMP-cluster with thousands of processors. Furthermore, its implementation can be prohibitively expensive for such a large-scale machine. IN this paper, they propose a novel coscheduling technique based on the DCS approach which can achieve coscheduling on very large SMP-clusters in a scalable, efficient, and cost-effective way. In the proposed technique, each local scheduler achieves coscheduling based upon message traffic between the components of parallel jobs. Message trapping is carried out at the user-level, eliminating the need for unsupported hardware or device-level programming. A sending process attaches its status to outgoing messages so local schedulers on remote nodes can make more intelligent scheduling decisions. Once scheduled, processes are guaranteed some minimum period of time to execute. This provides an opportunity to synchronize the parallel job's components across all nodes and …
Date: September 18, 2000
Creator: Yoo, A. B. & Jette, M. A.
System: The UNT Digital Library
CP violation in top physics at the NLC (open access)

CP violation in top physics at the NLC

Top quark is extremely sensitive to non-standard CP violating phases. General strategies for exposing different types of phases at the NLC are outlined. SUSY phase(s) cause PRA in t {yields} Wb. The transverse polarization of the {tau} in the reaction t {yields} b{tau}{nu} is extremely sensitive to a phase from the charged Higgs sector. Phase(s) from the neutral Higgs sector cause appreciable dipole moment effects and lead to sizable asymmetries in e{sup +}e{sup {minus}} {yields} t{anti t}H{sup 0} and e{sup +}e{sup {minus}} {yields} t{anti t}{nu}{sub e}{anti {nu}}{sub e}.
Date: September 18, 1996
Creator: Atwood, D. & Soni, A.
System: The UNT Digital Library
CPand t violation in neutrino oscillations (open access)

CPand t violation in neutrino oscillations

In this short lecture, we discuss some basic phenomenological aspects of CP and T violation in neutrino oscillation. Using CP/T trajectory diagrams in the bi-probability space, we try to sketch out some essential features of the interplay between the effect of CP/T violating phase and that of the matter in neutrino oscillation.
Date: September 18, 2003
Creator: Minakata, Hisakazu; Nunokawa, Hiroshi & Parke, Stephen
System: The UNT Digital Library
Dalitz Plot Analysis of the Decay B0(B0bar) to K^+/- pi^-/+ pi0 (open access)

Dalitz Plot Analysis of the Decay B0(B0bar) to K^+/- pi^-/+ pi0

The authors report a Dalitz-plot analysis of the charmless hadronic decays of neutral B mesons to K{sup {+-}}{pi}{sup {-+}}{pi}{sup 0}. With a sample of (231.8 {+-} 2.6) x 10{sup 6}{Upsilon}(4S) {yields} B{bar B} decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC, they measure the magnitudes and phases of the intermediate resonant and nonresonant amplitudes for B{sup 0} and {bar B}{sup 0} decays and determine the corresponding CP-averaged branching fractions and charge asymmetries. The inclusive branching fraction and CP-violating charge asymmetry are measured to be {Beta}(B{sup 0} {yields} K{sup +}{pi}{sup -}{pi}{sup 0}) = (35.7{sub -1.5}{sup +2.6} {+-} 2.2) x 10{sup -6}, and {Alpha}{sub CP} = -0.030{sub -0.051}{sup +0.045} {+-} 0.055 where the first errors are statistical and the second systematic. They observe the decay B{sup 0} {yields} K*{sup 0}(892){pi}{sup 0} with the branching fraction {Beta}(B{sup 0} {yields} K*{sup 0}(892){pi}{sup 0}) = (3.6{sub -0.8}{sup +0.7} {+-} 0.4) x 10{sup -6}. This measurement differs from zero by 5.6 standard deviations (including the systematic uncertainties). The selected sample also contains B{sup 0} {yields} {bar D}{sup 0}{pi}{sup 0} decays where {bar D}{sup 0} {yields} K{sup +}{pi}{sup -}, and they measure {Beta}(B{sup 0} {yields} {bar D}{sup 0}{pi}{sup 0}) = (2.93 …
Date: September 18, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prudent, X. et al.
System: The UNT Digital Library
Detailed Studies of Electron Cooling Friction Force. (open access)

Detailed Studies of Electron Cooling Friction Force.

High-energy electron cooling for RHIC presents many unique features and challenges. An accurate estimate of the cooling times requires detailed simulation of the electron cooling process. The first step towards such calculations is to have an accurate description of the cooling force. Numerical simulations are being used to explore various features of the friction force which appear due to several effects, including the anisotropy of the electron distribution in velocity space and the effect of a strong solenoidal magnetic field. These aspects are being studied in detail using the VORFAL code, which explicitly resolves close binary collisions. Results are compared with available asymptotic and empirical formulas and also, using the BETACOOL code, with direct numerical integration of less approximate expressions over the specified electron distribution function.
Date: September 18, 2005
Creator: Fedotov, A. V.; Bruhwiler, D. L.; Abell, D. T. & Sidorin, A. O.
System: The UNT Digital Library
Development and Testing of a Moving Granular Bed Filter at the Taiwan Industrial Technology Research Institute (open access)

Development and Testing of a Moving Granular Bed Filter at the Taiwan Industrial Technology Research Institute

The main purpose of developing high temperature gas cleaning technologies are to clean the gas under high temperature in order to be cost effective and to improve energy efficiency. Moving granular bed filters are technically and economically applicable for high temperature cleaning system because of low cost, possible to keep operation at a constant pressure drop, simple structure, easy in operation and maintenance, no high risk internals, and more tolerant to process thermal flow. Energy and Resource Laboratories, Taiwan Industrial Technology Research Institute (ERL/ITRI) has been developing a moving granular bed filter (MGBF) for BIGCC(Biomass Integrated Gasification Combined Cycle) high temperature gas cleanup. The filter granules move downwards directed by louver-like guide plates and the hot gases penetrate the MGBF horizontally. Filtration mechanisms include collection of the dust cake over the bed media surface and deep bed filtration. Stagnant zones of filter granules combining with the dusts always exist along the louver walls. Such stagnant zones often corrode the louver-like guide plates, increase the system pressure drop and decrease the total reaction efficiency that may endanger MGBF operation. Series louver and inert structure research that modify the granular flow pattern have been designed to eliminate the formation of these stagnant …
Date: September 18, 2002
Creator: Peng, C. Y.; Hsiau, S. S.; Lee, H. T.; Smid, J. & Wu, T-C.
System: The UNT Digital Library