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Measurement of the Branching Fractions of the Rare Decays B0 to Ds(*)+pi-,B0 to Ds(*)+rho-, and B0 to Ds(*)-K(*)+ (open access)

Measurement of the Branching Fractions of the Rare Decays B0 to Ds(*)+pi-,B0 to Ds(*)+rho-, and B0 to Ds(*)-K(*)+

The authors report the measurement of the branching fractions of the rare decays B{sup 0} {yields} D{sub s}{sup (*)+} {pi}{sup -}, B{sup 0} {yields} D{sub s}{sup (*)+} {rho}{sup -}, and B{sup 0} {yields} D{sub s}{sup (*)-} K{sup (*)+} in a sample of 381 x 10{sup 6} {Upsilon}(4S) decays into B{bar B} pairs collected with the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} storage ring. They present evidence for the decay B{sup 0} {yields} D{sub s}{sup -} K*{sup +} and the vector-vector decays B{sup 0} {yields} D{sub s}{sup *+} {rho}{sup -} and B{sup 0} {yields} D{sub s}{sup *-} K{sup *+}, as well as the first measurement of the vector meson polarization in these decays. They also determine the ratios of the CM-suppressed to CKM-favored amplitudes r(D{sup (*)}{pi}) and r(D{sup (*)}{rho}) in decays B{sup 0} {yields} D{sup (*)}{sup {+-}}{pi}{sup {-+}} and B{sup 0} {yields} D{sup (*)}{sup {+-}}{rho}{sup {-+}}, and comment on the prospects for measuring the Cp observable sin(2{beta} + {gamma}).
Date: April 16, 2008
Creator: Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E. et al.
System: The UNT Digital Library
Binary Pseudo-random Grating Standard for Calibration of Surface Profilometers (open access)

Binary Pseudo-random Grating Standard for Calibration of Surface Profilometers

We suggest and describe the use of a binary pseudo-random (BPR) grating as a standard test surface for measurement of the modulation transfer function (MTF) of interferometric microscopes. Knowledge of the MTF of a microscope is absolutely necessary to convert the measured height distribution of a surface undergoing metrology into an accurate power spectral density (PSD) distribution. For an'ideal' microscope with an MTF function independent of spatial frequency out to the Nyquist frequency of the detector array with zero response at higher spatial frequencies, a BPR grating would produce a flat 1D PSD spectrum, independent of spatial frequency. For a'real' instrument, the MTF is found as the square root of the ratio of the PSD spectrum measured with the BPR grating to the'ideal,' spatial frequency independent, PSD spectrum. We present the results from a measurement of the MTF of MicromapTM-570 interferometric microscope demonstrating a high efficiency for the calibration method.
Date: January 16, 2008
Creator: Yashchuk, Valeriy; Yashchuk, Valeriy V.; McKinney, Wayne R. & Takacs, Peter Z.
System: The UNT Digital Library
Search for New Physics Beyond the Standard Model at BaBar (open access)

Search for New Physics Beyond the Standard Model at BaBar

A review of selected recent BaBar results are presented that illustrate the ability of the experiment to search for physics beyond the standard model. The decays B {yields} {tau}{nu} and B {yields} s{gamma} provide constraints on the mass of a charged Higgs. Searches for Lepton Flavour Violation could provide a clear signal for beyond the standard model physics. Babar does not observe any signal for New Physics with the current dataset.
Date: April 16, 2008
Creator: Barrett, Matthew & U., /Brunel
System: The UNT Digital Library
Scale Matters: An Action Plan for Realizing Sector-Wide"Zero-Energy" Performance Goals in Commercial Buildings (open access)

Scale Matters: An Action Plan for Realizing Sector-Wide"Zero-Energy" Performance Goals in Commercial Buildings

It is widely accepted that if the United States is to reduce greenhouse gas emissions it must aggressively address energy end use in the building sector. While there have been some notable but modest successes with mandatory and voluntary programs, there have also been puzzling failures to achieve expected savings. Collectively, these programs have not yet reached the majority of the building stock, nor have they yet routinely produced very large savings in individual buildings. Several trends that have the potential to change this are noteworthy: (1) the growing market interest in 'green buildings' and 'sustainable design', (2) the major professional societies (e.g. AIA, ASHRAE) have more aggressively adopted significant improvements in energy efficiency as strategic goals, e.g. targeting 'zero energy', carbon-neutral buildings by 2030. While this vision is widely accepted as desirable, unless there are significant changes to the way buildings are routinely designed, delivered and operated, zero energy buildings will remain a niche phenomenon rather than a sector-wide reality. Toward that end, a public/private coalition including the Alliance to Save Energy, LBNL, AIA, ASHRAE, USGBC and the World Business Council for Sustainable Development (WBCSD) are developing an 'action plan' for moving the U.S. commercial building sector towards zero …
Date: June 16, 2008
Creator: Selkowitz, Stephen; Selkowitz, Stephen; Granderson, Jessica; Haves, Philip; Mathew, Paul & Harris, Jeff
System: The UNT Digital Library
Merger Histories of Galaxy Halos and Implications for Disk Survival (open access)

Merger Histories of Galaxy Halos and Implications for Disk Survival

The authors study the merger histories of galaxy dark matter halos using a high resolution {Lambda}CDM N-body simulation. The merger trees follow {approx} 17,000 halos with masses M{sub 0} = (10{sup 11} - 10{sup 13})h{sup -1}M{sub {circle_dot}} at z = 0 and track accretion events involving objects as small as m {approx_equal} 10{sup 10} h{sup -1}M{sub {circle_dot}}. They find that mass assembly is remarkably self-similar in m/M{sub 0}, and dominated by mergers that are {approx}10% of the final halo mass. While very large mergers, m {approx}> 0.4 M{sub 0}, are quite rare, sizeable accretion events, m {approx} 0.1 M{sub 0}, are common. Over the last {approx} 10 Gyr, an overwhelming majority ({approx} 95%) of Milky Way-sized halos with M{sub 0} = 10{sup 12} h{sup -1}M{sub {circle_dot}} have accreted at least one object with greater total mass than the Milky Way disk (m > 5 x 10{sup 10} h{sup -1}M{sub {circle_dot}}), and approximately 70% have accreted an object with more than twice that mass (m > 10{sup 11} h{sup -1}M{sub {circle_dot}}). The results raise serious concerns about the survival of thin-disk dominated galaxies within the current paradigm for galaxy formation in a {Lambda}CDM universe. in order to achieve a {approx} 70% …
Date: May 16, 2008
Creator: Stewart, Kyle R.; Bullock, James S.; Wechsler, Risa H.; Maller, Ariyeh H. & Zentner, Andrew R.
System: The UNT Digital Library
Making Amines Strong Bases: Thermodynamic Stabilization ofProtonated Guests in a Highly-Charged Supramolecular Host (open access)

Making Amines Strong Bases: Thermodynamic Stabilization ofProtonated Guests in a Highly-Charged Supramolecular Host

A highly-charged, cavity-containing supramolecular assembly formed by metal-ligand interactions acts as a host to dramatically shift the effective basicity of encapsulated protonated amine guests. The scope of encapsulated protonated amine and phosphine guests shows size selectivity consistent with a constrained binding environment. Protonation of the encapsulated guests is confirmed by {sup 31}P NMR studies, mass spectrometry studies, and the pH dependence of guest encapsulation. Rates of guest self-exchange were measured using the Selective Inversion Recovery method and were found to correlate with the size rather than the basicity of the guests. The activation parameters for guest self-exchange are consistent with the established mechanism for guest exchange. The binding constants of the protonated amines are then used to calculate the effective basicity of the encapsulated amines. Depending on the nature of the guest, shifts in the effective basicities of the encapsulated amines of up to 4.5 pK{sub a} units are observed, signifying a substantial stabilization of the protonated form of the guest molecule and effectively making phosphines and amines strong bases.
Date: April 16, 2007
Creator: Pluth, Michael D.; Bergman, Robert G. & Raymond, Kenneth N.
System: The UNT Digital Library
The Beta-Neutrino Correlation in Sodium-21 and Other Nuclei (open access)

The Beta-Neutrino Correlation in Sodium-21 and Other Nuclei

We have measured the mbox beta - nu correlation coefficient,a_beta nu, in 21Na using a laser-trapped sample. We measure the energyspectrum of the recoil nuclei by measuring their time-of-flight incoincidence with the atomic electrons shaken off in beta decay. Highdetectionefficiency of these low-energy electrons allows good countingstatistics, even with low trap density, which suppresses thephotoassociation of molecular sodium, which can cause a large systematicerror. Our measurement, with a 1 percent fractional uncertainty, agreeswith the Standard Model prediction but disagrees with our previousmeasurement which was susceptible to error introduced by molecularsodium. We summarize precise measurements of a_ beta nu and theirconsequences for searches for Beyond Standard Model scalar and tensorcurrent couplings.
Date: January 16, 2008
Creator: Vetter, Paul A.; Abo-Shaeer, Jamil; Freedman, Stuart J. & Maruyama, Reina
System: The UNT Digital Library
A Summary of Recent Experimental Research on Ion Energy and Charge States of Pulsed Vacuum Arcs (open access)

A Summary of Recent Experimental Research on Ion Energy and Charge States of Pulsed Vacuum Arcs

The paper reviews the results of vacuum arc experimental investigations made collaboratively by research groups from Berkeley and Tomsk over the last two years, i.e. since the last ISDEIV in 2006. Vacuum arc plasma of various metals was produced in pulses of a few hundred microseconds duration, and the research focussed on three topics: (i) the energy distribution functions for different ion charge states, (ii) the temporal development of the ion charge state distribution, and (iii) the evolution of the mean directed ion velocities during plasma expansion. A combined quadruple mass-to-charge and energy ana-lyzer (EQP by HIDEN Ltd) and a time-of-flight spectrometer were employed. Cross-checking data by those complimen-tary techniques helped to avoid possible pitfalls in interpre-tation. It was found that the ion energy distribution func-tions in the plasma were independent of the ion charge state, which implies that the energy distribution on a substrate are not equal to due to acceleration in the substrate's sheath. In pulsed arc mode, the individual ion charge states fractions showed changes leading to a decrease of the mean charge state toward a steady-state value. This decrease can be re-duced by lower arc current, higher pulse repetition rate and reduced length of the discharge …
Date: June 16, 2008
Creator: Oks, Efim M.; Yushkov, Georgy Yu. & Anders, Andre
System: The UNT Digital Library
Electronic structure of cobalt nanocrystals suspended inliquid (open access)

Electronic structure of cobalt nanocrystals suspended inliquid

The electronic structure of cobalt nanocrystals suspended in liquid as a function of size has been investigated using in-situ x-ray absorption and emission spectroscopy. A sharp absorption peak associated with the ligand molecules is found that increases in intensity upon reducing the nanocrystal size. X-ray Raman features due to d-d and to charge-transfer excitations of ligand molecules are identified. The study reveals the local symmetry of the surface of {var_epsilon}-Co phase nanocrystals, which originates from a dynamic interaction between Co nanocrystals and surfactant + solvent molecules.
Date: July 16, 2007
Creator: Liu, Hongjian; Guo, Jinghua; Yin, Yadong; Augustsson, Andreas; Dong, Chungli; Nordgren, Joseph et al.
System: The UNT Digital Library
Relativistic Dark Matter at the Galactic Center (open access)

Relativistic Dark Matter at the Galactic Center

In a large region of the supersymmetry parameter space, the annihilation cross section for neutralino dark matter is strongly dependent on the relative velocity of the incoming particles. We explore the consequences of this velocity dependence in the context of indirect detection of dark matter from the galactic center. We find that the increase in the annihilation cross section at high velocities leads to a flattening of the halo density profile near the galactic center and an enhancement of the annihilation signal.
Date: November 16, 2007
Creator: Amin, Mustafa A.; /Stanford U., Phys. Dept. /KIPAC, Menlo Park & Wizansky, Tommer
System: The UNT Digital Library
Measurement of the beta-neutrino correlation of sodium-21 usingshakeoff electrons (open access)

Measurement of the beta-neutrino correlation of sodium-21 usingshakeoff electrons

The beta-neutrino correlation coefficient, a_beta nu, ismeasured in 21Na by detecting the time-of-flight of the recoil nucleusdetected in coincidence with the atomic electrons shaken off in betadecay. The sample of 21Na is confined in a magneto-optic trap. Highdetection efficiency allows low trap density, which suppresses thephotoassociation of molecular sodium, which can cause a large systematicerror. Suppressing the fraction of trapped atoms in the excited stateusing a dark trap also reduces the photoassociation process, and datataken with this technique are consistent. The main remaining systematicuncertainties come from the measurement of the position and size of theatom trap, and the subtraction of background. We find mbox a_betanu=0.5502(60), in agreement with the Standard Model prediction of mboxa_beta nu=0.553(2), and disagreeing with a previous measurement which wassusceptible to an error introduced by the presence of molecularsodium.
Date: January 16, 2007
Creator: Vetter, Paul A.; Abo-Shaeer, Jamil R.; Freedman, Stuart J. & Maruyama, Reina
System: The UNT Digital Library
A Shape Memory Polymer Dialysis Needle Adapter for the Reduction of Hemodynamic Stress within Arteriovenous Grafts (open access)

A Shape Memory Polymer Dialysis Needle Adapter for the Reduction of Hemodynamic Stress within Arteriovenous Grafts

A deployable, shape memory polymer adapter is investigated for reducing the hemodynamic stress caused by a dialysis needle flow within an arteriovenous graft. Computational fluid dynamics simulations of dialysis sessions with and without the adapter demonstrate that the adapter provides a significant decrease in the wall shear stress. In vitro flow visualization measurements are made within a graft model following delivery and actuation of a prototype shape memory polymer adapter. Vascular access complications resulting from arteriovenous (AV) graft failures account for over $1 billion per year in the health care costs of dialysis patients in the U.S.[1] The primary mode of failure of arteriovenous fistulas (AVF's) and polytetrafluoroethylene (PTFE) grafts is the development of intimal hyperplasia (IH) and the subsequent formation of stenotic lesions, resulting in a graft flow decline. The hemodynamic stresses arising within AVF's and PTFE grafts play an important role in the pathogenesis of IH. Studies have shown that vascular damage can occur in regions where there is flow separation, oscillation, or extreme values of wall shear stress (WSS).[2] Nevaril et al.[3] show that exposure of red blood cells to WSS's on the order of 1500 dynes/cm2 can result in hemolysis. Hemodynamic stress from dialysis needle flow …
Date: August 16, 2006
Creator: Ortega, J M; Small, W; Wilson, T S; Benett, W; Loge, J & Maitland, D J
System: The UNT Digital Library
Feasibility of Diffraction Radiation for a Non-invasive Diagnostics of the SLAC Electron Beam (open access)

Feasibility of Diffraction Radiation for a Non-invasive Diagnostics of the SLAC Electron Beam

The development of the non-invasive bunch size diagnostics based on the diffraction radiation is now in progress in frame of TPU-KEK-SLAC collaboration. The experimental test of a transverse beam size measurement was performed successful on the KEK-ATF extracted electron beam. However many difficulties emerge if we going from the one GeV electron energy to the several tenth GeV electron beams. The extremely high Lorenz-factor value gives rise to the some problems, such as large contribution of a radiation from an accelerator construction elements in submillimeter wavelength region, extremely pre-wave zone effect even in the optical range, exceeding of the electron beam divergence over the diffraction radiation cone, and so on. More over, the sensitivity of the method based on the optical diffraction radiation from flat slit target decrease catastrophic when an electron energy increase up to several tenth GeV. We suggest the new method based on the phase shift on the slit target, consisting on the two semi-planes which are turned at a some angle one to other (crossed target technique) and present here the results of experimental test of this technique. Also we discuss the origins of indicated difficulties and suggest the ways of these problems solution.
Date: May 16, 2006
Creator: Naumenko, G.; Potylitsyn, A.; U., /Tomsk Polytechnic; Araki, S.; Aryshev, A.; Hayano, H. et al.
System: The UNT Digital Library
Unraveling the Fanconi anaemia-DNA repair connection through DNA helicase and translocase activities (open access)

Unraveling the Fanconi anaemia-DNA repair connection through DNA helicase and translocase activities

How the Fanconi anaemia (FA) chromosome stability pathway functions to cope with interstrand crosslinks and other DNA lesions has been elusive, even after FANCD1 proved to be BRCA2, a partner of Rad51 in homologous recombination. The identification and characterization of two new Fanconi proteins having helicase motifs, FANCM and FANCJ/BRIP1/BACH1, implicates the FANC nuclear core complex as a participant in recognizing or processing damaged DNA, and the BRIP1 helicase as acting independently of this complex.
Date: August 16, 2005
Creator: Thompson, L H
System: The UNT Digital Library
Elastic constants and volume changes associated with two high-pressure rhombohedral phase transformations in vanadium (open access)

Elastic constants and volume changes associated with two high-pressure rhombohedral phase transformations in vanadium

We present results from ab-initio electronic-structure calculations of mechanical properties of the rhombohedral phase of vanadium reported in recent experiments (R Ia), and other predicted high-pressure phases (R Ib and bcc), focusing on properties relevant to dynamic experiments. We find that of the three transitions the largest volume collapse (1.3%) is for the R Ia to R Ib transition. Calculations of the single crystal and polycrystal elastic constants reveal a remarkably small discontinuity across the phase transitions even at zero temperature where the transitions are first order.
Date: October 16, 2007
Creator: Lee, B; Rudd, R E; Klepeis, J E & Becker, R
System: The UNT Digital Library
Managing Carbon Regulatory Risk in Utility Resource Planning:Current Practices in the Western United States (open access)

Managing Carbon Regulatory Risk in Utility Resource Planning:Current Practices in the Western United States

Concerns about global climate change have substantially increased the likelihood that future policy will seek to minimize carbon dioxide emissions. Assuch, even today, electric utilities are making resource planning and investment decisions that consider the possible implications of these future carbon regulations. In this article, we examine the manner in which utilities assess the financial risks associated with future carbon regulations within their long-term resource plans. We base our analysis on a review of the most recent resource plans filed by fifteen electric utilities in the Western United States. Virtually all of these utilities made some effort to quantitatively evaluate the potential cost of future carbon regulations when analyzing alternate supply- and demand-side resource options for meeting customer load. Even without Federal climate regulation in the U.S., the prospect of that regulation is already having an impact on utility decision-making and resource choices. That said, the methods and assumptions used by utilities to analyze carbon regulatory risk, and the impact of that analysis on their choice of a particular resource strategy, vary considerably, revealing a number of opportunities for analytic improvement. Though our review focuses on a subset of U.S. electric utilities, this work holds implications for all electric utilities …
Date: May 16, 2008
Creator: Barbose, Galen; Wiser, Ryan; Phadke, Amol & Goldman, Charles
System: The UNT Digital Library
Correlation between Strand Stability and Magnet Performance (open access)

Correlation between Strand Stability and Magnet Performance

Magnet programs at BNL, LBNL and FNAL have observed instabilities in high J{sub c} Nb{sub 3}Sn strands and magnets made from these strands. This paper correlates the strand stability determined from a short sample-strand test to the observed magnet performance. It has been observed that strands that carry high currents at high fields (greater than 10T) cannot sustain these same currents at low fields (1-3T) when the sample current is fixed and the magnetic field is ramped. This suggests that the present generation of strand is susceptible to flux jumps (FJ). To prevent flux jumps from limiting stand performance, one must accommodate the energy released during a flux jump. To better understand FJ this work has focused on wire with a given sub-element diameter and shows that one can significantly improve stability by increasing the copper conductivity (higher residual resistivity ratio, RRR, of the Cu). This increased stability significantly improves the conductor performance and permits it to carry more current.
Date: April 16, 2005
Creator: Dietderich, Daniel R.; Bartlett, Scott E.; Caspi, Shlomo; Ferracin, Paolo; G ourlay, Stephen A.; Higley, Hugh C. et al.
System: The UNT Digital Library
Performances of Induction System for Nanosecond Mode Operation (open access)

Performances of Induction System for Nanosecond Mode Operation

An induction system comprises an array of single turn pulse transformers. Ferromagnetic cores of transformers are toroids that are stacked along the longitudinal core axis. Another name for this array is a fraction transformer or an adder. The primary and secondary windings of such a design have one turn. The step up mode is based on the number of primary pulse sources. The secondary windings are connected in series. Performances of such a system for the nanosecond range mode operation are different in comparison to the performances of traditional multi-turn pulse transformers, which are working on a 100+ nanosecond mode operation. In this paper, the author discusses which aspects are necessary to take into account for the high power nanosecond fractional transformer designs. The engineering method of the nanosecond induction system design is presented.
Date: May 16, 2006
Creator: Krasnykh, Anatoly
System: The UNT Digital Library
Geometrical Effects in Plasma Stability and Dynamics of Coherent Structures in the Divertor (open access)

Geometrical Effects in Plasma Stability and Dynamics of Coherent Structures in the Divertor

Plasma dynamics in the divertor region is strongly affected by a variety of phenomena associated with the magnetic field geometry and the shape of the divertor plates. One of the most universal effects is the squeezing of a normal cross-section of a thin magnetic flux-tube on its way from the divertor plate to the main SOL. It leads to decoupling of the most unstable perturbations in the divertor legs from those in the main SOL. For perturbations on either side of the X-point, this effect can be cast as a boundary condition at some 'control surface' situated near the X-point. We discuss several boundary conditions proposed thus far and assess the influence of the magnetic field geometry on them. Another set of geometrical effects is related to the transformation of a flux-tube that occurs when it is displaced in such a way that its central magnetic field line coincides with some other field line, and the magnetic field is not perturbed. These flute-like displacements are of a particular interest for the low-beta edge plasmas. It turns out that this transformation may also lead to a considerable deformation of a flux-tube cross-section; in addition, the distance between plasma particles occupying the …
Date: May 16, 2007
Creator: Ryutov, D. D. & Cohen, R. H.
System: The UNT Digital Library
A Possible Connection Between Dark Energy And the Hierarchy (open access)

A Possible Connection Between Dark Energy And the Hierarchy

Recently it was suggested that the dark energy maybe related to the well-known hierarchy between the Planck scale ({approx} 10{sup 19} GeV) and the TeV scale. The same brane-world setup to address this hierarchy problem may also in principle address the smallness problem of dark energy. Specifically, the Planck-SM hierarchy ratio was viewed as a quantum gravity-related, dimensionless fine structure constant where various physical energy scales in the system are associated with the Planck mass through different powers of the 'gravity fine structure constant'. In this paper we provide a toy model based on the Randall-Sundrum geometry where SUSY-breaking is induced by the coupling between a SUSY-breaking Higgs field on the brane and the KK gravitinos. We show that the associated Casimir energy density indeed conforms with the dark energy scale.
Date: November 16, 2007
Creator: Chen, Pisin; /SLAC /KIPAC, Menlo Park; Gu, Je-An & /NCTS, Hsinchu
System: The UNT Digital Library
Validation of DNA probes for molecular cytogenetics by mapping onto immobilized circular DNA (open access)

Validation of DNA probes for molecular cytogenetics by mapping onto immobilized circular DNA

Fluorescence in situ hybridization (FISH) is a sensitive and rapid procedure to detect gene rearrangements in tumor cells using non-isotopically labeled DNA probes. Large insert recombinant DNA clones such as bacterial artificial chromosome (BAC) or P1/PAC clones have established themselves in recent years as preferred starting material for probe preparations due to their low rates of chimerism and ease of use. However, when developing probes for the quantitative analysis of rearrangements involving genomic intervals of less than 100kb, careful probe selection and characterization are of paramount importance. We describe a sensitive approach to quality control probe clones suspected of carrying deletions or for measuring clone overlap with near kilobase resolution. The method takes advantage of the fact that P1/PAC/BAC's can be isolated as circular DNA molecules, stretched out on glass slides and fine-mapped by multicolor hybridization with smaller probe molecules. Two examples demonstrate the application of this technique: mapping of a gene-specific {approx}6kb plasmid onto an unusually small, {approx}55kb circular P1 molecule and the determination of the extent of overlap between P1 molecules homologous to the human NF-?B2 locus. The relatively simple method presented here does not require specialized equipment and may thus find widespread applications in DNA probe preparation …
Date: December 16, 2008
Creator: Greulich-Bode, Karin; Wang, Mei; Rhein, Andreas; Weier, Jingly & Weier, Heinz-Ulli
System: The UNT Digital Library
Direct drive heavy-ion-beam inertial fusion at high coupling efficiency (open access)

Direct drive heavy-ion-beam inertial fusion at high coupling efficiency

Issues with coupling efficiency, beam illumination symmetry, and Rayleigh-Taylor instability are discussed for spherical heavy-ion-beam-driven targets with and without hohlraums. Efficient coupling of heavy-ion beams to compress direct-drive inertial fusion targets without hohlraums is found to require ion range increasing several-fold during the drive pulse. One-dimensional implosion calculations using the LASNEX inertial confinement fusion target physics code shows the ion range increasing fourfold during the drive pulse to keep ion energy deposition following closely behind the imploding ablation front, resulting in high coupling efficiencies (shell kinetic energy/incident beam energy of 16% to 18%). Ways to increase beam ion range while mitigating Rayleigh-Taylor instabilities are discussed for future work.
Date: May 16, 2008
Creator: Logan, B. G.; Perkins, L. J. & Barnard, J. J.
System: The UNT Digital Library
Energy Efficiency Standards and Labels in North America: Opportunities for Harmonization (open access)

Energy Efficiency Standards and Labels in North America: Opportunities for Harmonization

To support the North American Energy Working Group's Expert Group on Energy Efficiency (NAEWG-EE), USDOE commissioned the Collaborative Labeling and Appliance Standards Program (CLASP) to prepare a resource document comparing current standards, labels, and test procedure regulations in Canada, Mexico, and the United States. The resulting document reached the following conclusions: Out of 24 energy-using products for which at least one of the three countries has energy efficiency regulations, three products -- refrigerators/freezers, split system central air conditioners, and room air conditioners -- have similar or identical minimum energy performance standards (MEPS) in the three countries. These same three products, as well as three-phase motors, have similar or identical test procedures throughout the region. There are 10 products with different MEPS and test procedures, but which have the short-term potential to develop common test procedures, MEPS, and/or labels. Three other noteworthy areas where possible energy efficiency initiatives have potential for harmonization are standby losses, uniform endorsement labels, and a new standard or label on windows. This paper explains these conclusions and presents the underlying comparative data.
Date: May 16, 2002
Creator: Vanwiemcgrory, Laura; Wiel, Stephen; Van Wie McGrory, Laura & Harrington, Lloyd
System: The UNT Digital Library
Analytical analysis of longitudinal space charge effects for a bunched beam with radial dependence (open access)

Analytical analysis of longitudinal space charge effects for a bunched beam with radial dependence

The longitudinal space-charge (LSC) force can be a major cause of the microbunching instability in the linac for an x-ray free-electron laser. In this paper, the LSC-induced beam modulation is studied using an integral equation approach that takes into account the transverse (radial) variation of the LSC field for both the coasting-beam limit and a bunched beam. Variation of the beam energy and the transverse beam size is also incorporated. We discuss the validity of this approach and compare it with other analytical analyses as well as numerical simulations.
Date: June 16, 2008
Creator: Wu, Juhao; Huang, Zhirong & Emma, Paul
System: The UNT Digital Library