Magnetic design of the axisymmetric throttle-coil addition to the tandem mirror experiment-upgrade (open access)

Magnetic design of the axisymmetric throttle-coil addition to the tandem mirror experiment-upgrade

The TMX-U magnet set has incorporated new axisymmetric throttle coils and fan-reversing transition magnets. This new magnet geometry, which will allow for the experimental verification of new physics issues related to axicell tandem mirrors, encompasses both engineering and physics considerations. Engineering considerations include structural integrity plus neutral beam and diagnostic access. Physics issues include the stability and radial transport of the confined plasma. We have calculated the magnetic field using the magnetic field code, EFFI, and the plasma stability and surface curvatures using the plasma stability code, TEBASCO. Our magnet design allows the axisymmetric throttle mirror to be varied from the end-cell mirror value of 2 to a peak of 6 T.
Date: November 28, 1983
Creator: Wong, R.L.
System: The UNT Digital Library
State of California initiative in geothermal development: its objectives, accomplishments and schedules (open access)

State of California initiative in geothermal development: its objectives, accomplishments and schedules

California has the most abundant known reserves of geothermal resources in the nation, and California State government has taken several important actions to accelerate the environmentally acceptable development of geothermal energy. The roles played by various California State government agencies and the legislature to accomplish this goal are discussed.
Date: November 28, 1978
Creator: Reed, C. S.
System: The UNT Digital Library
Sharp Reduction of the Secondary Electron Emission Yield from Grooved Surfaces (open access)

Sharp Reduction of the Secondary Electron Emission Yield from Grooved Surfaces

The effect of an artificially-enhanced rough surface on the secondary electron emission yield (SEY) was investigated both theoretically and experimentally. Analytical studies on triangular and rectangular grooved surfaces show the connection between the characteristic parameters of a given geometry to the SEY reduction. The effect of a strong magnetic field is also discussed. SEY of grooved samples have been measured and the results agree with Monte-Carlo simulations.
Date: November 28, 2007
Creator: Pivi, M. T. F.; King, F. K.; Kirby, R. E.; Ruabenheimer, T. O.; Stupakov, G. & Le Pimpec, F.
System: The UNT Digital Library
An Incompressible Navier-Stokes with Particles Algorithm andParallel Implementation (open access)

An Incompressible Navier-Stokes with Particles Algorithm andParallel Implementation

We present a variation of an adaptive projection method forcomputing solutions to the incompressible Navier-Stokes equations withsuspended particles. To compute the divergence-free component of themomentum forcing due to the particle drag, we employ an approach whichexploits the locality and smoothness of the Laplacian of the projectionoperator applied to the discretized particle drag force. We presentconvergence and performance results to demonstrate the effectiveness ofthis approach.
Date: November 28, 2006
Creator: Martin, Daniel F.; Colella, Phillip & Keen, Noel D.
System: The UNT Digital Library
Search for CPT and Lorentz Violation in B0-B0bar Oscillations with Dilepton Events (open access)

Search for CPT and Lorentz Violation in B0-B0bar Oscillations with Dilepton Events

We report results of a search for CPT and Lorentz violation in B{sup 0}-{bar B}{sup 0} oscillations using inclusive dilepton events from 232 million {Upsilon}(4S) {yields} B{bar B} decays recorded by the BABAR detector at the PEP-II B Factory at SLAC. We find 2.8{sigma} significance, compatible with no signal, for variations in the complex CPT violation parameter z at the Earth's sidereal frequency and extract values for the quantities {Delta}a{sub {mu}} in the general Lorentz-violating standard-model extension. The spectral powers for variations in z over the frequency range 0.26 year{sup -1} to 2.1 day{sup -1} are also compatible with no signal.
Date: November 28, 2007
Creator: Collaboration, The BABAR & Aubert, B.
System: The UNT Digital Library
Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses (open access)

Optical Damage Threshold of Silicon for Ultrafast Infrared Pulses

We present measurements of the optical damage threshold of crystalline silicon in air for ultrafast pulses in the near infrared. The wavelengths tested span a range from the telecommunications band at 1550 nm, extending to 2260 nm. We discuss the motivation for the measurements and give theoretical context. We then describe the experimental setup, diagnostics, and procedure. The results show a breakdown threshold of 0.2J/cm{sup 2} at 1550 nm and 1.06 ps FWHM pulse duration, and a weak dependence on wavelength.
Date: November 28, 2007
Creator: Cowan, Benjamin M. & /Tech-X, Boulder /SLAC
System: The UNT Digital Library
Highly Effective Polarized Electron Sources Based on Strained Semiconductor Superlattice with Distributed Bragg Reflector (open access)

Highly Effective Polarized Electron Sources Based on Strained Semiconductor Superlattice with Distributed Bragg Reflector

Resonance enhancement of the quantum efficiency of new polarized electron photocathodes based on a short-period strained superlattice structures is reported. The superlattice is a part of an integrated Fabry-Perot optical cavity. We demonstrate that the Fabry-Perot resonator enhances the quantum efficiency by the order of magnitude in the wavelength region of the main polarization maximum. The high structural quality implied by these results points to the very promising application of these photocathodes for spin-polarized electron sources.
Date: November 28, 2007
Creator: Gerchikov, L. G.; Aulenbacher, K.; Clendenin, J. E.; Kuz'michev, V. V.; Mamaev, Yu. A.; Maruyama, T. et al.
System: The UNT Digital Library
Summary of Polarized e-/e+ Source Presentations (open access)

Summary of Polarized e-/e+ Source Presentations

The development of polarized electron sources in the 1970s capable of generating beams for injection into electron accelerators has been a major enabling factor for spin physics with electrons during the past quarter century. These sources continue to be refined for higher polarization and better operability. Recent developments were presented at this workshop in both plenary sessions and in 2 separate parallel sessions. The ILC plans to utilize not only a polarized electron source but also a polarized positron source. The current state of two types of positron sources were presented. This paper is a brief summary of all of these presentations.
Date: November 28, 2007
Creator: Clendenin, J. E.
System: The UNT Digital Library
Improvements in Monte Carlo Simulation of Large Electron Fields (open access)

Improvements in Monte Carlo Simulation of Large Electron Fields

Two Monte Carlo systems, EGSnrc and Geant4, were used to calculate dose distributions in large electron fields used in radiotherapy. Source and geometry parameters were adjusted to match calculated results with measurement. Both codes were capable of accurately reproducing the measured dose distributions of the 6 electron beams available on the accelerator. Depth penetration was matched to 0.1 cm. Depth dose curves generally agreed to 2% in the build-up region, although there is an additional 2-3% experimental uncertainty in this region. Dose profiles matched to 2% at the depth of maximum dose in the central region of the beam, out to the point of the profile where the dose begins to fall rapidly. A 3%/3mm match was obtained outside the central region except for the 6 MeV beam, where dose differences reached 5%. The discrepancy observed in the bremsstrahlung tail in published results that used EGS4 is no longer evident. The different systems required different source energies, incident beam angles, thicknesses of the exit window and primary foils, and distance between the primary and secondary foil. These results underscore the requirement for an experimental benchmark of electron scatter for beam energies and foils relevant to radiotherapy.
Date: November 28, 2007
Creator: Faddegon, Bruce A.; /UC, San Francisco; Perl, Joseph & Asai, Makoto
System: The UNT Digital Library
3C454.3 Revelas the Structure and Physics of its 'Blazar Zone' (open access)

3C454.3 Revelas the Structure and Physics of its 'Blazar Zone'

Recent multi-wavelength observations of 3C454.3, in particular during its giant outburst in 2005, put severe constraints on the location of the 'blazar zone', its dissipative nature, and high energy radiation mechanisms. As the optical, X-ray, and millimeter light-curves indicate, significant fraction of the jet energy must be released in the vicinity of the millimeter-photosphere, i.e. at distances where, due to the lateral expansion, the jet becomes transparent at millimeter wavelengths. We conclude that this region is located at {approx} 10 parsecs, the distance coinciding with the location of the hot dust region. This location is consistent with the high amplitude variations observed on {approx} 10 day time scale, provided the Lorentz factor of a jet is {Gamma}{sub j} {approx} 20. We argue that dissipation is driven by reconfinement shock and demonstrate that X-rays and {gamma}-rays are likely to be produced via inverse Compton scattering of near/mid IR photons emitted by the hot dust. We also infer that the largest gamma-to-synchrotron luminosity ratio ever recorded in this object - having taken place during its lowest luminosity states - can be simply due to weaker magnetic fields carried by a less powerful jet.
Date: November 28, 2007
Creator: Sikora, M.; Moderski, R. & Madejski, G.M.
System: The UNT Digital Library
Characterization and Electrochemical Performance of SubstitutedLiNi0.4Co0.2-yAlyMn0.4O2 (0<_y<_0.2) Cathode Materials (open access)

Characterization and Electrochemical Performance of SubstitutedLiNi0.4Co0.2-yAlyMn0.4O2 (0<_y<_0.2) Cathode Materials

A complete series of LiNi0.4Co0.2-yAlyMn0.4O2 (0<_y<_0.2) materials have been synthesized and investigated as cathode materials for lithium ion batteries. When cycled between 2.0 and 4.3 V vs. Li/Li+ at a current density of 0.1 mA/cm2, stable capacities of ~;;160 mAh/g for y=0 to ~;;110 mAh/g for y=0.2 are achieved. Upon increasing the current density, it is found that all materials containing aluminum show reduced polarization and improved rate performance. The optimal performance at all current densities was found for the compound with y=0.05. The effect of aluminumsubstitution on the crystal structure of the host is discussed.
Date: November 28, 2007
Creator: Wilcox, James D. & Doeff, Marca M.
System: The UNT Digital Library
Commissioning the LCLS Injector (open access)

Commissioning the LCLS Injector

The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) project presently under construction at SLAC. The injector section, from drive laser and RF photocathode gun through first bunch compressor chicane, was installed in fall 2006. Initial system commissioning with an electron beam was completed in August 2007, with the goal of a 1.2-micron emittance in a 1-nC bunch clearly demonstrated. The second phase of commissioning, including second bunch compressor and full linac, is planned for 2008, with FEL commissioning in 2009. We report experimental results and experience gained in the first phase of commissioning, including the photo-cathode drive laser, RF gun, photocathode, S-band and X-band RF systems, first bunch compressor, and the various beam diagnostics.
Date: November 28, 2007
Creator: Akre, R.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G. et al.
System: The UNT Digital Library
Parametric Modeling of Electron Beam Loss in Synchrotron Light Sources (open access)

Parametric Modeling of Electron Beam Loss in Synchrotron Light Sources

Synchrotron light is used for a wide variety of scientific disciplines ranging from physical chemistry to molecular biology and industrial applications. As the electron beam circulates, random single-particle collisional processes lead to decay of the beam current in time. We report a simulation study in which a combined neural network (NN) and first-principles (FP) model is used to capture the decay in beam current due to Touschek, Bremsstrahlung, and Coulomb effects. The FP block in the combined model is a parametric description of the beam current decay where model parameters vary as a function of beam operating conditions (e.g. vertical scraper position, RF voltage, number of the bunches, and total beam current). The NN block provides the parameters of the FP model and is trained (through constrained nonlinear optimization) to capture the variation in model parameters as operating condition of the beam changes. Simulation results will be presented to demonstrate that the proposed combined framework accurately models beam decay as well as variation to model parameters without direct access to parameter values in the model.
Date: November 28, 2007
Creator: Sayyar-Rodsari, B.; Schweiger, C.; Hartman, E.; Corbett, J.; Lee, M.; Lui, P. et al.
System: The UNT Digital Library
Bunch Length Measurements in SPEAR3 (open access)

Bunch Length Measurements in SPEAR3

A series of bunch length measurements were made in SPEAR3 for two different machine optics. In the achromatic optics the bunch length increases from the low-current value of 16.6ps rms to about 30ps at 25ma/bunch yielding an inductive impedance of -0.17{Omega}. Reducing the momentum compaction factor by a factor of {approx}60 [1] yields a low-current bunch length of {approx}4ps rms. In this paper we review the experimental setup and results.
Date: November 28, 2007
Creator: Corbett, W.J.; Fisher, A.; Huang, X.; Safranek, J.; Sebek, J.; /SLAC et al.
System: The UNT Digital Library
Normal zone detectors for a large number of inductively coupled coils (open access)

Normal zone detectors for a large number of inductively coupled coils

In order to protect a set of inductively coupled superconducting magnets, it is necessary to locate and measure normal zone voltages that are small compared with the mutual and self-induced voltages. The method described in this paper uses two sets of voltage measurements to locate and measure one or more normal zones in any number of coupled coils. One set of voltages is the outputs of bridges that balance out the self-induced voltages. The other set of voltages can be the voltages across the coils, although alternatives are possible. The two sets of equations form a single combined set of equations. Each normal zone location or combination of normal zones has a set of these combined equations associated with it. It is demonstrated that the normal zone can be located and the correct set chosen, allowing determination of the size of the normal zone. Only a few operations take place in a working detector: multiplication of a constant, addition, and simple decision-making. In many cases the detector for each coil, although weakly linked to the other detectors, can be considered to be independent.
Date: November 28, 1983
Creator: Owen, E. W. & Shimer, D. W.
System: The UNT Digital Library
Software for reflectivity calculations of x-ray mirrors. Revision 1 (open access)

Software for reflectivity calculations of x-ray mirrors. Revision 1

With VAX software and the data libraries of Henke and Biggs-Lighthill, we have created a library of atomic scattering factors f/sub 1/ and f/sub 2/ in the energy range 0.1 keV to 10.0 keV. Scattering factor values for the elements Z = 1 to Z = 94 and in the above energy range are stored in a keyed access library (key = element symbol). This library allows one to calculate reflectivity rapidly and fold it with other components in an x-ray detector channel. Additional software allows the library data to be easily extended to higher energies. Applications have so far included KB x-ray microscopes and low energy spectrometers with mirror channels.
Date: November 28, 1984
Creator: Auerbach, J.M. & Tirsell, K.G.
System: The UNT Digital Library
Design of the electromagnetic fluctuations diagnostic for MFTF-B (open access)

Design of the electromagnetic fluctuations diagnostic for MFTF-B

The Electromagnetic Fluctuations (EMF) diagnostic will be used to monitor ion fluctuations which could be unstable in MFTF-B. Each probe assembly includes a high impedance electrostatic probe to measure potential fluctuations, and a group of nested, single turn loops to measure magnetic fluctuations in three directions. Eventually, more probes and loops will be added to each probe assembly for making more detailed measurements. The sensors must lie physically close to the plasma edge and are radially positionable. Also, probes at separate axial locations can be positioned to connect along the same magnetic field line. These probes are similar in concept to the rf probes used on TMX, but the high thermal load for 30-second shots on MFTF-B requires a water-cooled design along with temperature monitors. Each signal channel has a bandwidth of .001 to 150 MHz and is monitored by up to four different data channels which obtain amplitude and frequency information. This paper describes the EMF diagnostic and presents the detailed mechanical and electrical designs.
Date: November 28, 1983
Creator: House, P.A.; Goerz, D.A. & Martin, R.
System: The UNT Digital Library
Numerical simulation of turbulent mixing in shock-tube experiments (open access)

Numerical simulation of turbulent mixing in shock-tube experiments

We have carried out a number of 2D numerical simulations on an ALE code for shock-tube experiments in which a shock crosses one or more contact discontinuities and, after traveling through a homogeneous medium, reflects off a rigid wall at the end of the shock-tube and re-crosses the contact discontinuity. We have considered two-fluid and three-fluid experiments: the first fluid, which carries the original shock, is air; the other fluids are helium, freon, SF/sub 6/, or air again. Helium is lighter than air, while freon and SF/sub 6/ are heavier than air. The interface(s) between the fluids serve as contact discontinuities and are subjected to the original shock, the re-shock, and subsequent rarefactions/compressions. 9 refs., 6 figs.
Date: November 28, 1988
Creator: Mikaelian, K.O.
System: The UNT Digital Library
/sup 163/Dy as a solar neutrino detector (open access)

/sup 163/Dy as a solar neutrino detector

The possibility of using /sup 163/Dy as a low threshold solar neutrino detector is discussed. Solar neutrino absorption cross sections are calculated, and expected capture rates presented.
Date: November 28, 1984
Creator: Bennett, C. L.
System: The UNT Digital Library
Legal Aspects of National Implementation of the Chemical Weapons Convention (open access)

Legal Aspects of National Implementation of the Chemical Weapons Convention

The author discusses some legal aspects of measures at the national level to implement the Chemical Weapons Convention (CWC). These implementing measures are universal, applying not only to the few States Parties that will declare and destroy chemical weapons, but also to the many States Parties that have never had a chemical weapons program. This new need for national measures to implement multilateral arms control agreements has generated unease due to a perception that implementation may be burdensome and at odds with national law. In 1993, concerns arose that the complexity of integrating the treaty with national law would cause each nation to effectuate the Convention without regard to what other nations were doing, thereby engendering significant disparities in implementation steps among States Parties. The author discusses progress among several States in actually developing national CWC implementing measures. Implementing measures from Australia, Norway, South Africa, and Sweden were available to him in English through the PTS. He compares them in order to illustrate different approaches to national implementation that are emerging. Of course, it is important to note that this brief survey necessarily omitted examination of the existing ``background`` of other, related domestic laws that these signatories might also have …
Date: November 28, 1994
Creator: Tanzman, Edward A.; Zeuli, Anthony R. & Kellman, Barry
System: The UNT Digital Library
Proton reaction cross sections measured in the BNL/AGS E943 experiment (open access)

Proton reaction cross sections measured in the BNL/AGS E943 experiment

We have measured proton reaction cross sections over a wide mass and energy range at the Brookhaven AGS accelerator. The samples were elemental Be, C, Al, Cu, W, and Pb; the measurements were carried out at ten incident proton kinetic energies in the range 0.54 to 7.8 GeV. The experiment was similar to an earlier experiment in the 200-550 MeV range by Renberg et al. The new results are in good agreement with those of Renberg et al. at the overlap point near 550 MeV. The combined results of the two experiments show an energy dependence expected from the behavior of the nucleon-nucleon cross sections. The results are reproduced by calculations based on variants of the impulse approximation and Glauber theory.
Date: November 28, 2000
Creator: Dietrich, F S; Hartouni, E P; Schmid, G J; Soltz, R; Abfalterer, W P; Haight, R C et al.
System: The UNT Digital Library
Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics (open access)

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

The Large Hadron Collider (LHC) at CERN promises a major step forward in the understanding of the fundamental nature of matter. The ATLAS experiment is a general-purpose detector for the LHC, whose design was guided by the need to accommodate the wide spectrum of possible physics signatures. The major remit of the ATLAS experiment is the exploration of the TeV mass scale where groundbreaking discoveries are expected. In the focus are the investigation of the electroweak symmetry breaking and linked to this the search for the Higgs boson as well as the search for Physics beyond the Standard Model. In this report a detailed examination of the expected performance of the ATLAS detector is provided, with a major aim being to investigate the experimental sensitivity to a wide range of measurements and potential observations of new physical processes. An earlier summary of the expected capabilities of ATLAS was compiled in 1999 [1]. A survey of physics capabilities of the CMS detector was published in [2]. The design of the ATLAS detector has now been finalised, and its construction and installation have been completed [3]. An extensive test-beam programme was undertaken. Furthermore, the simulation and reconstruction software code and frameworks have …
Date: November 28, 2011
Creator: Aad, G.; Abat, E.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A. et al.
System: The UNT Digital Library
Design and Factory Test of the E /E- Frascati Linear Accelerator for DAFNE (open access)

Design and Factory Test of the E /E- Frascati Linear Accelerator for DAFNE

The electron-positron accelerator for the DAFNE project has been built and is in test at Titan Beta in Dublin, CA. This S-Band RF linac system utilizes four 45 MW sledded klystrons and 16-3 m accelerating structures to achieve the required performance. It delivers a 4 ampere electron beam to the positron converter and accelerates the resulting positrons to 550 MeV. The converter design uses a 4.3T pulsed tapered flux compressor along with a pseudo-adiabatic tapered field to a 5 KG solenoid over the first two positron accelerating sections. Quadrupole focusing is used after 100 MeV. The system performance is given in Table 1. This paper briefly describes the design and development of the various subassemblies in this system and gives the initial factory test data.
Date: November 28, 2011
Creator: Anamkath, H.; Lyons, S.; Nett, D.; Treas, P.; Whitham, K.; Zante, T. et al.
System: The UNT Digital Library
Neutronics and mass transport in a chemical reactor associated with controlled thermonuclear fusion reactor (open access)

Neutronics and mass transport in a chemical reactor associated with controlled thermonuclear fusion reactor

The formation of ozone from oxygen and the dissociation carbon dioxide to carbon monoxide and oxygen is studied in a gamma-neutron chemical process blanket associated with a controlled thermonuclear reactor. Materials used for reactor tube wall will affect the efficiency of the energy absorption by the reactants and consequently the yield of reaction products. Three kinds of materials, aluminum, stainless steel and fiber (Al/sub 2/O/sub 3/)-aluminium are investigated for the tube wall material in the study.
Date: November 28, 1976
Creator: Dang, V D; Steinberg, M; Lazareth, O W & Powell, J R
System: The UNT Digital Library