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205 kA pulse power supply for neutrino focusing horns (open access)

205 kA pulse power supply for neutrino focusing horns

A new underground beamline is being constructed at Fermilab to generate and focus a beam of neutrinos on a detector 450 miles away in Soudan, Minnesota. A compact modulator utilizing capacitive energy storage and SCRs as the switching element has been built and tested at Fermilab. The 0.9 F capacitor bank operates at less than 1 kV. It delivers its output of up to 240 kA directly to the two series connected focusing horns via a multi-layer radiation hard stripline [1]. Dual pulse width capability allows for ready selection of 5.2 ms, for slow beam spills, or 2.6 ms operation for reduced thermal stresses on the focusing horns during fast spill. Intended for installation in an underground equipment room, the design incorporates several novel features to facilitate transport, installation, and maintenance. Various designs were examined to arrive at the most economical approach for providing the high pulse currents to the horns located in the very high radiation field, up to 3 x 10{sup 7} kRads/yr absorbed dose of the beamline. These included charge recovery and electronic polarity reversal systems. The direct coupling approach was selected for its overall economy and compactness. The system has been operational for several months and …
Date: June 21, 2002
Creator: Kenneth R. Bourkland, Kevin Roon and David Tinsley
System: The UNT Digital Library
Absolute Measurement of Electron Cloud Density (open access)

Absolute Measurement of Electron Cloud Density

Beam interaction with background gas and walls produces ubiquitous clouds of stray electrons that frequently limit the performance of particle accelerator and storage rings. Counterintuitively we obtained the electron cloud accumulation by measuring the expelled ions that are originated from the beam-background gas interaction, rather than by measuring electrons that reach the walls. The kinetic ion energy measured with a retarding field analyzer (RFA) maps the depressed beam space-charge potential and provides the dynamic electron cloud density. Clearing electrode current measurements give the static electron cloud background that complements and corroborates with the RFA measurements, providing an absolute measurement of electron cloud density during a 5 {micro}s duration beam pulse in a drift region of the magnetic transport section of the High-Current Experiment (HCX) at LBNL.
Date: June 21, 2007
Creator: Covo, M K; Molvik, A W; Cohen, R H; Friedman, A; Seidl, P A; Logan, G et al.
System: The UNT Digital Library
Advances in Target Design for Heavy-Ion Fusion (open access)

Advances in Target Design for Heavy-Ion Fusion

Over the past few years, the emphasis in heavy ion target design has moved from the distributed radiator target to the 'hybrid' target because the hybrid target allows a larger beam focal spot than the distributed radiator ({approx} 5 mm radius rather than {approx} 2 mm radius). The larger spot relaxes some of the requirements on the driver, but introduces some new target physics issues. Most notable is the use of shine shields and shims in the hohlraum to achieve symmetry rather than achieving symmetry by beam placement. The shim is a thin layer of material placed on or near the capsule surface to block a small amount of excess radiation. While we have been developing this technique for the heavy ion hybrid target, the technique can be used in any indirect drive target. We have begun testing the concept of a shim to improve symmetry using a double-ended z-pinch hohlraum on the Sandia Z-machine. Experiments using shimmed thin wall capsules have shown that we can reverse the sign of a P{sub 2} asymmetry and significantly reduce the size of a P{sub 4} asymmetry. These initial experiments demonstrate the concept of a shim as another method for controlling early time …
Date: June 21, 2005
Creator: Callahan, D. A.; Tabak, M.; Bennett, G. R.; Cuneo, M. E.; Vesey, R. A.; Nikroo, A. et al.
System: The UNT Digital Library
Advection of Surface-Derived Organic Carbon Fuels Microbial Reduction in Bangladesh Groundwater (open access)

Advection of Surface-Derived Organic Carbon Fuels Microbial Reduction in Bangladesh Groundwater

None
Date: June 21, 2012
Creator: Mailloux, B. J.; Trembath-Reichert, E.; Cheung, J.; Watson, M.; Stute, M.; Freyer, G. A. et al.
System: The UNT Digital Library
Analysis of explosion-induced releases of toxic materials at an environmental restoration project (open access)

Analysis of explosion-induced releases of toxic materials at an environmental restoration project

Prior to 1988, a variety of materials were buried on the US DOE Oak Ridge Reservation. Records of the disposal operations are incomplete and toxic materials may have been placed adjacent to potential explosives. One of the safety concerns in conducting an environmental restoration project at the burial sites, is the possibility of an explosion which could release toxic materials to the atmosphere. A safety analysis examined the consequences of such releases by first postulating an upper bound for the strength of an explosive. A correlation, developed by Steindler and Seefeldt of Argonne National Laboratory, was then used to estimate the amount and particle-size distribution of the material that could become airborne from the explosion. The estimated amount of airborne material was the source term in an atmospheric dispersion model which was used to calculate infinite-time, concentration-time integrals and 5-minute, time- weighted average concentrations at locations down-wind from the explosion. The dispersion model includes particle deposition as a function of particle-size distribution class. The concentration-time integrals and average concentrations were compared to published guidelines to assess the consequences of an accidental explosion.
Date: June 21, 1993
Creator: Bloom, S. G. & Moon, W. H. Jr.
System: The UNT Digital Library
ARE MAGNETIC MONOPOLES HADRONS? (open access)

ARE MAGNETIC MONOPOLES HADRONS?

The charges of magnetic monopoles are constrained to a multiple of 2{pi} times the inverse of the elementary unit electric charge. In the standard model, quarks have fractional charge, raising the question of whether the basic magnetic monopole unit is a multiple of 2{pi} or three times that. A simple lattice construction shows how a magnetic monopole of the lower strength is possible if it interacts with gluonic fields as well. Such a monopole is thus a hadron. This is consistent with the construction of magnetic monopoles in grand unified theories.
Date: June 21, 2004
Creator: CREUTZ, M.
System: The UNT Digital Library
B-Meson Semileptonic Decays at BaBar (open access)

B-Meson Semileptonic Decays at BaBar

We report on the measurements of B-meson semileptonic decays at BABAR. The studies include precision measurement of |V{sub cb}| by a combined HQE fit to hadronic mass and electron energy spectral moments in inclusive B {yields} X{sub c}{ell}{nu} decays, measurements of |V{sub cb}| in inclusive and exclusive B {yields} X{sub u}{ell}{nu} decays, and measurements of B {yields} ({pi},{rho}){ell}{nu} decay rates.
Date: June 21, 2006
Creator: Golubev, V. B.
System: The UNT Digital Library
Boosting Piezoelectricity by 3D Printing PVDF-MoS2 Composite as a Conformal and High-Sensitivity Piezoelectric Sensor (open access)

Boosting Piezoelectricity by 3D Printing PVDF-MoS2 Composite as a Conformal and High-Sensitivity Piezoelectric Sensor

Article describes how additively manufactured flexible and high-performance piezoelectric devices are highly desirable for sensing and energy harvesting of 3D conformal structures. This study reports a significantly enhanced piezoelectricity in polyvinylidene fluoride (PVDF) achieved through the in situ dipole alignment of PVDF within PVDF-2D molybdenum disulfide composite by 3D printing.
Date: June 21, 2023
Creator: Islam, M.D, Nurul; Rupom, Rifat Hasan; Adhikari, Pashupati R.; Demchuk, Zoriana; Popov, Ivan; Sokolov, Alexei P. et al.
System: The UNT Digital Library
Brain, Music, and Non-Poisson Renewal Processes (open access)

Brain, Music, and Non-Poisson Renewal Processes

Article discussing research that shows both music composition and brain function, as revealed by the electroencephalogram (EEG) analysis, are renewal non-Poisson processes living in the nonergodic dominion.
Date: June 21, 2007
Creator: Bianco, Simone; Ignaccolo, Massimiliano; Rider, Mark S.; Ross, Mary J.; Winsor, Phil & Grigolini, Paolo
System: The UNT Digital Library
Calculation of the cross section for top quark production (open access)

Calculation of the cross section for top quark production

The authors summarize calculations of the cross section for top quark production at hadron colliders within the context of perturbative quantum chromodynamics, including resummation of the effects of initial-state soft gluon radiation to all orders in the strong coupling strength. In their approach they resume the universal leading-logarithm contributions, and they restrict the calculation to the region of phase space that is demonstrably perturbative. They compare the approach with other methods. They present predictions of the physical cross section as a function of the top quark mass in proton-antiproton reactions at center-of-mass energies of 1.8 and 2.0 TeV, and they discuss estimated uncertainties.
Date: June 21, 1996
Creator: Berger, E. L. & Contopanagos, H.
System: The UNT Digital Library
Cavity BPM with Dipole-Mode-Selective Coupler (open access)

Cavity BPM with Dipole-Mode-Selective Coupler

In this paper, we present a novel position sensitive signal pickup scheme for a cavity BPM. The scheme utilizes the H-plane of the waveguide to couple magnetically to the side of the cavity, which results in a selective coupling to the dipole mode and a total rejection of the monopole mode. This scheme greatly simplifies the BPM geometry and relaxes machining tolerances. We will present detailed numerical studies on such a cavity BPM, analyze its resolution limit and tolerance requirements for a nanometer resolution. Finally present the measurement results of a X-band prototype.
Date: June 21, 2006
Creator: Li, Zenghai; Johnson, Ronald; Smith, Stephen R.; Naito, Takashi & Rifkin, Jeffrey
System: The UNT Digital Library
Charge transport in hybrid nanorod-polymer composite photovoltaiccells (open access)

Charge transport in hybrid nanorod-polymer composite photovoltaiccells

Charge transport in composites of inorganic nanorods and aconjugated polymer is investigated using a photovoltaic device structure.We show that the current-voltage (I-V) curves in the dark can be modelledusing the Shockley equation modified to include series and shuntresistance at low current levels, and using an improved model thatincorporates both the Shockley equation and the presence of a spacecharge limited region at high currents. Under illumination, theefficiency of photocurrent generation is found to be dependent on appliedbias. Furthermore, the photocurrent-light intensity dependence was foundto be sublinear. An analysis of the shunt resistance as a function oflight intensity suggests that the photocurrent as well as the fill factoris diminished as a result of increased photoconductivity of the activelayer at high light intensity. By studying the intensity dependence ofthe open circuit voltage for nanocrystals with different diameters andthus ! band gaps, it was inferred that Fermi-level pinning occurs at theinterface between the aluminum electrode and the nanocrystal.
Date: June 21, 2002
Creator: Huynh, Wendy U.; Dittmer, Janke J.; Teclemariam, Nerayo; Milliron, Delia; Alivisatos, A. Paul & Barnham, Keith W.J.
System: The UNT Digital Library
Co-simulation for performance prediction of integrated building and HVAC systems - An analysis of solution characteristics using a two-body system (open access)

Co-simulation for performance prediction of integrated building and HVAC systems - An analysis of solution characteristics using a two-body system

Integrated performance simulation of buildings and heating, ventilation and airconditioning (HVAC) systems can help reducing energy consumption and increasing occupant comfort. However, no single building performance simulation (BPS) tool offers suffcient capabilities and flexibilities to analyze integrated building systems and to enable rapid prototyping of innovative building and system technologies. One way to alleviate this problem is to use co-simulation to integrate different BPS tools. Co-simulation approach represents a particular case of simulation scenario where at least two simulators solve coupled differential-algebraic systems of equations and exchange data that couples these equations during the time integration. This article analyzes how co-simulation influences consistency, stability and accuracy of the numerical approximation to the solution. Consistency and zero-stability are studied for a general class of the problem, while a detailed consistency and absolute stability analysis is given for a simple two-body problem. Since the accuracy of the numerical approximation to the solution is reduced in co-simulation, the article concludes by discussing ways for how to improve accuracy.
Date: June 21, 2010
Creator: Trcka, Marija; L.M. Hensena, Jan & Wetter, Michael
System: The UNT Digital Library
Co-simulation of innovative integrated HVAC systems in buildings (open access)

Co-simulation of innovative integrated HVAC systems in buildings

Integrated performance simulation of buildings HVAC systems can help in reducing energy consumption and increasing occupant comfort. However, no single building performance simulation (BPS) tool offers sufficient capabilities and flexibilities to analyze integrated building systems and to enable rapid prototyping of innovative building and system technologies. One way to alleviate this problem is to use co-simulation, as an integrated approach to simulation. This article elaborates on issues important for co-simulation realization and discusses multiple possibilities to justify the particular approach implemented in the here described co-simulation prototype. The prototype is validated with the results obtained from the traditional simulation approach. It is further used in a proof-of-concept case study to demonstrate the applicability of the method and to highlight its benefits. Stability and accuracy of different coupling strategies are analyzed to give a guideline for the required coupling time step.
Date: June 21, 2010
Creator: Trcka, Marija; Hensena, Jan L.M. & Wetter, Michael
System: The UNT Digital Library
Coherent Beam Stability in the Low Momentum Compaction Lattice (open access)

Coherent Beam Stability in the Low Momentum Compaction Lattice

The beam dynamics for a quasi-isochronous lattice differs from that in the usual case of a lattice with a large positive momentum compaction factor. In particular, the quasi-isochronous lattice allows us to double the number of bunches which may be an attractive option for colliders. However, microwave instability and, as we show, longitudinal head-tail instability set the threshold for the beam current.
Date: June 21, 2006
Creator: Heifets, S. & Novokhatski, A.
System: The UNT Digital Library
A Collective Collision Operator for DSMC (open access)

A Collective Collision Operator for DSMC

A new scheme to simulate elastic collisions in particle simulation codes is presented. The new scheme aims at simulating the collisions in the highly collisional regime, in which particle simulation techniques typically become computationally expensive.The new scheme is based on the concept of a grid-based collision field. According to this scheme, the particles perform a single collision with the background grid during a time step. The properties of the background field are calculated from the moments of the distribution function accumulated on the grid. The collision operator is based on the Langevin equation. Based on comparisons with other methods, it is found that the Langevin method overestimates the collision frequency for dilute gases.
Date: June 21, 2000
Creator: GALLIS,MICHAIL A. & TORCZYNSKI,JOHN R.
System: The UNT Digital Library
Commentary on “Studies on Molar Volume, Dielectric Properties and Refractive Indices of Cyanex 923 + Benzene/Xylene at 300 K” (open access)

Commentary on “Studies on Molar Volume, Dielectric Properties and Refractive Indices of Cyanex 923 + Benzene/Xylene at 300 K”

This article provides a commentary on Redlich-Kister equation coefficients for binary benzene + cyanex 923 and xylene + cyanex 923.
Date: June 21, 2017
Creator: Acree, William E. (William Eugene)
System: The UNT Digital Library
COMMISSIONING OF A HIGH-BRIGHTNESS PHOTOINJECTOR FOR COMPTON SCATTERING X-RAY SOURCES (open access)

COMMISSIONING OF A HIGH-BRIGHTNESS PHOTOINJECTOR FOR COMPTON SCATTERING X-RAY SOURCES

Compton scattering of intense laser pulses with ultrarelativistic electron beams has proven to be an attractive source of high-brightness x-rays with keV to MeV energies. This type of x-ray source requires the electron beam brightness to be comparable with that used in x-ray free-electron lasers and laser and plasma based advanced accelerators. We describe the development and commissioning of a 1.6 cell RF photoinjector for use in Compton scattering experiments at LLNL. Injector development issues such as RF cavity design, beam dynamics simulations, emittance diagnostic development, results of sputtered magnesium photo-cathode experiments, and UV laser pulse shaping are discussed. Initial operation of the photoinjector is described.
Date: June 21, 2007
Creator: Anderson, S G; Gibson, D J; Hartemann, F V; Messerly, M; Shverdin, M; Siders, C W et al.
System: The UNT Digital Library
Comparison of DOTC and Legacy Benziger Dry Aminated TATBs and PBX-9502 (open access)

Comparison of DOTC and Legacy Benziger Dry Aminated TATBs and PBX-9502

None
Date: June 21, 2013
Creator: Hoffman, D. M.; Martin-Williams, A.; Gagliardi, F. J.; Lorenz, T. K.; Willley, T. & Tran, T. D.
System: The UNT Digital Library
Comparison of LiFePO4 from different sources (open access)

Comparison of LiFePO4 from different sources

The lithium iron phosphate chemistry is plagued by the poor conductivity and slow diffusion in the solid phase. In order to alleviate these problems, various research groups have adopted different strategies including decreasing the particle sizes, increasing the carbon content, and adding dopants. In this study, we obtained LiFePO{sub 4} powders and/or electrodes from six different sources and used a combined model-experimental approach to compare the performance. Samples ranged from 0.4% to 15% ''in-situ'' carbon. In addition, particle sizes varied by as much as an order of magnitude between samples. The study detailed in this manuscript allows us to provide insight into the relative importance of the conductivity of the samples compared to the particle size, the impact of having a distribution in particle sizes, and ideas for making materials in order to maximize the power capability of this chemistry.
Date: June 21, 2004
Creator: Striebel, Kathryn; Shim, Joongpyo; Srinivasan, Venkat & Newman, John
System: The UNT Digital Library
Compensation for Bunch Emittance in a Magnetization and Space Charge Dominated Beam. (open access)

Compensation for Bunch Emittance in a Magnetization and Space Charge Dominated Beam.

In order to obtain sufficient cooling rates for the Relativistic Heavy Ion Collider (RHIC) electron cooling, a bunched beam with high bunch charge, high repetition frequency and high energy is required and it is necessary to use a ''magnetized'' beam, i.e., an electron beam with non-negligible angular momentum. Applying a longitudinal solenoid field on the cathode can generate such a beam, which rotates around its longitudinal axis in a field-free region. This paper suggests how a magnetized beam can be accelerated and transported from a RF photocathode electron gun to the cooling section without significantly increasing its emittance. The evolution of longitudinal slices of the beam under a combination of space charge and magnetization is investigated, using paraxial envelope equations and numerical simulations. We find that we must modify the traditional method of compensating for emittance as used for normal non-magnetized beam with space charge to account for magnetization. The results of computer simulations of successful compensation are presented. Alternately, we show an electron bunch density distribution for which all slices propagate uniformly and which does not require emittance compensation.
Date: June 21, 2004
Creator: Chang, X.; Ben-Zvi, Ilan & Kewisch, J.
System: The UNT Digital Library
Compensatory Paracrine Mechanisms That Define The Urothelial Response to Injury in Partial Bladder Outlet Obstruction (open access)

Compensatory Paracrine Mechanisms That Define The Urothelial Response to Injury in Partial Bladder Outlet Obstruction

Diseases and conditions affecting the lower urinary tract are a leading cause of dysfunctional sexual health, incontinence, infection, and kidney failure. The growth, differentiation, and repair of the bladder's epithelial lining are regulated, in part, by fibroblast growth factor (FGF)-7 and -10 via a paracrine cascade originating in the mesenchyme (lamina propria) and targeting the receptor for FGF-7 and -10 within the transitional epithelium (urothelium). The FGF-7 gene is located at the 15q15-q21.1 locus on chromosome 15 and four exons generate a 3.852-kb mRNA. Five duplicated FGF-7 gene sequences that localized to chromosome 9 were predicted not to generate functional protein products, thus validating the use of FGF-7-null mice as an experimental model. Recombinant FGF-7 and -10 induced proliferation of human urothelial cells in vitro and transitional epithelium of wild-type and FGF-7-null mice in vivo.To determine the extent that induction of urothelial cell proliferation during the bladder response to injury is dependent on FGF-7, an animal model of partial bladder outlet obstruction was developed. Unbiased stereology was used to measure the percentage of proliferating urothelial cells between obstructed groups of wild-type and FGF-7-null mice. The stereological analysis indicated that a statistical significant difference did not exist between the two groups, …
Date: June 21, 2007
Creator: Bassuk, James; Lendvay, Thomas S.; Sweet, Robert; Han, Chang-Hee; Soygur, Tarkan; Cheng, Jan-Fang et al.
System: The UNT Digital Library
Constraining Dark Matter in Galactic Substructure (open access)

Constraining Dark Matter in Galactic Substructure

In this paper we discuss detection prospects by combining two different aspects of the gamma-ray signal: the angular distribution and the photon counts probability distribution function (PDF).
Date: June 21, 2013
Creator: Baxter, Eric J.; Dodelson, Scott; Koushiappas, Savvas M. & Strigari, Louis E.
System: The UNT Digital Library
Correlation Spectroscopy of Minor Species: Signal Purification and Distribution Analysis (open access)

Correlation Spectroscopy of Minor Species: Signal Purification and Distribution Analysis

We are performing experiments that use fluorescence resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS) to monitor the movement of an individual donor-labeled sliding clamp protein molecule along acceptor-labeled DNA. In addition to the FRET signal sought from the sliding clamp-DNA complexes, the detection channel for FRET contains undesirable signal from free sliding clamp and free DNA. When multiple fluorescent species contribute to a correlation signal, it is difficult or impossible to distinguish between contributions from individual species. As a remedy, we introduce ''purified FCS'' (PFCS), which uses single molecule burst analysis to select a species of interest and extract the correlation signal for further analysis. We show that by expanding the correlation region around a burst, the correlated signal is retained and the functional forms of FCS fitting equations remain valid. We demonstrate the use of PFCS in experiments with DNA sliding clamps. We also introduce ''single molecule FCS'', which obtains diffusion time estimates for each burst using expanded correlation regions. By monitoring the detachment of weakly-bound 30-mer DNA oligomers from a single-stranded DNA plasmid, we show that single molecule FCS can distinguish between bursts from species that differ by a factor of 5 in diffusion constant.
Date: June 21, 2006
Creator: Laurence, T A; Kwon, Y; Yin, E; Hollars, C; Camarero, J A & Barsky, D
System: The UNT Digital Library