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4th generation light source instrumentation. (open access)

4th generation light source instrumentation.

This working group on 4th Generation Light Source (4GLS) Instrumentation was a follow-up to the opening-discussion on Challenges in Beam Profiling. It was in parallel with the Feedback Systems session. We filled the SSRL Conference Room with about 25 participants. The session opened with an introduction by Lumpkin. The target beam parameter values for a few-angstrom, self-amplified spontaneous emissions (SASE) experiment and for a diffraction-limited soft x-ray storage ring source were addressed. Instrument resolution would of course need to be 2-3 times better than the value measured, if possible. The nominal targeted performance parameters are emittance (1-2{pi} mm mrad), bunch length (100 fs), peak-current (l-5 kA), beam size (10 {micro}m), beam divergence (1 {micro}rad), energy spread (2 x 10{sup {minus}4}), and beam energy (10's of GeV). These are mostly the SASE values, and the possible parameters for a diffraction-limited soft x-ray source would be relaxed somewhat. Beam stability and alignment specifications in the sub-micron domain for either device are anticipated.
Date: September 24, 1998
Creator: Lumpkin, A.
System: The UNT Digital Library
Absorptance measurements of transmissive optical components by the surface thermal lensing technique (open access)

Absorptance measurements of transmissive optical components by the surface thermal lensing technique

The surface thermal lensing technique (STL) successfully resolved and measured the absorptance of transmissive optical components: near- normal angle-of-incidence anti-reflectors and beam splatters. The STL system uses an Ar ion laser to pump the components at 514.5 mn. The absorptance-induced surface deformation diffracts the HeNe probe beam into a photo-detector. The signal intensity was calibrated with a sample of known absorptance. The optical components were designed to function in a copper vapor laser (CVL) transport system, and were previously tested for absorptance with a high power CVL system at 511 rtm. To assure proper absorptance data from the STL system, the pump laser power densities were set at the operational level of the coatings, absorptance time trends were monitored, and absorptance area scans were made. Both types of transmissive optics are more stable than the CVL high reflectors that were measured in another study. Parameter studies based on Fresnel diffraction theory were also performed to optimize experimental condition. The STL system was assessed to have 10 ppb sensitivity for absorption measurement given 2 W of pump power.
Date: September 24, 1997
Creator: Chow, R.; Taylor, J. R.; Wu, Z. L.; Han, Y. & Tian, L. Y.
System: The UNT Digital Library
The Acid Hydrolysis Mechanism of Acetals Catalyzed by a Supramolecular Assembly in Basic Solution (open access)

The Acid Hydrolysis Mechanism of Acetals Catalyzed by a Supramolecular Assembly in Basic Solution

A self-assembled supramolecular host catalyzes the hydrolysis of acetals in basic aqueous solution. The mechanism of hydrolysis is consistent with the Michaelis-Menten kinetic model. Further investigation of the rate limiting step of the reaction revealed a negative entropy of activation ({Delta}S{double_dagger} = -9 cal mol{sup -1}K{sup -1}) and an inverse solvent isotope effect (k(H{sub 2}O)/k(D{sub 2}O) = 0.62). These data suggest that the mechanism of hydrolysis that takes place inside the assembly proceeds through an A-2 mechanism, in contrast to the A-1 mechanism operating in the uncatalyzed reaction. Comparison of the rates of acetal hydrolysis in the assembly with the rate of the reaction of unencapsulated substrates reveals rate accelerations of up to 980 over the background reaction for the substrate diethoxymethane.
Date: September 24, 2008
Creator: Pluth, Michael D.; Bergman, Robert G. & Raymond, Kenneth N.
System: The UNT Digital Library
Adjustable Permanent Quadrupoles Using Rotating Magnet Material Rods for the Next Linear Collider (open access)

Adjustable Permanent Quadrupoles Using Rotating Magnet Material Rods for the Next Linear Collider

The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 132 Tesla, with a maximum gradient of 135 Tesla per meter, an adjustment range of +0-20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micrometer during the 20% adjustment. In an effort to reduce estimated costs and increase reliability, several designs using hybrid permanent magnets have been developed. All magnets have iron poles and use either Samarium Cobalt or Neodymium Iron to provide the magnetic fields. Two prototypes use rotating rods containing permanent magnetic material to vary the gradient. Gradient changes of 20% and center shifts of less than 20 microns have been measured. These data are compared to an equivalent electromagnet prototype.
Date: September 24, 2001
Creator: al., James T Volk et
System: The UNT Digital Library
The Advanced Radiographic Capability, A Major Upgrade Of The Computer Controls For The National Ignition Facility* (open access)

The Advanced Radiographic Capability, A Major Upgrade Of The Computer Controls For The National Ignition Facility*

None
Date: September 24, 2013
Creator: Brunton, G.; Marshall, C.; Lagin, L.; Tietbohl, G.; Fishler, B.; Fisher, J. et al.
System: The UNT Digital Library
Analysis of the carbon-related 'blue' luminescence in GaN (open access)

Analysis of the carbon-related 'blue' luminescence in GaN

The properties of a broad 2.86 eV photoluminescence band in carbon-doped GaN were studied as a function of C-doping level, temperature, and excitation density. The results are consistent with a C{sub Ga}-C{sub N} deep donor-deep acceptor recombination mechanism as proposed by Seager et al. For GaN:C grown by molecular-beam epitaxy (MBE) the 2.86 eV band is observed in Si co-doped layers exhibiting high n-type conductivity as well as in semi-insulating material. For low excitation density (4 W/cm{sup 2}) the 2.86 eV band intensity decreases as a function of cw-laser exposure time over a period of many minutes. The transient behavior is consistent with a model based on carrier diffusion and charge trapping-induced Coulomb barriers. The temperature dependence of the blue luminescence below 150 K was different for carbon-contaminated GaN grown by metalorganic vapor phase epitaxy (MOVPE) compared to C-doped MBE GaN.
Date: September 24, 2004
Creator: Armitage, R.; Yang, Q. & Weber, E.R.
System: The UNT Digital Library
Applications of Crystal Plasticity in Multiscale Modeling (open access)

Applications of Crystal Plasticity in Multiscale Modeling

Multiscale modeling with crystal plasticity constitutive relations is used to determine the average response of a polycrystal. The measured crystallographic texture of a copper shaped charge liner is used in a crystal plasticity model to construct a yield surface that exhibits normal-shear coupling. Simulations with this yield surface model demonstrate the spinning behavior observed in the spin formed copper shaped charges.
Date: September 24, 2001
Creator: Becker, R.; Busche, M.; Schwartz, A. J. & Kumar, M.
System: The UNT Digital Library
Approaching maximal performance of longitudinal beam compression in induction accelerator drivers (open access)

Approaching maximal performance of longitudinal beam compression in induction accelerator drivers

Longitudinal beam compression occurs before final focus and fusion chamber beam transport and is a key process determining initial conditions for final focus hardware. Determining the limits for maximal performance of key accelerator components is an essential element of the effort to reduce driver costs. Studies directed towards defining the limits of final beam compression including considerations such as maximal available compression, effects of longitudinal dispersion and beam emittance, combining pulse-shaping with beam compression to reduce the total number of beam manipulators, etc., are given. Several possible techniques are illustrated for utilizing the beam compression process to provide the pulse shapes required by a number of targets. Without such capabilities to shape the pulse, an additional factor of two or so of beam energy would be required by the targets.
Date: September 24, 1986
Creator: Mark, J. W. K.; Ho, D. D. M.; Brandon, S. T.; Chang, C. L.; Drobot, A. T.; Faltens, A. et al.
System: The UNT Digital Library
Are the J/psi and chi_c A dependencies the same? (open access)

Are the J/psi and chi_c A dependencies the same?

It has been empirically observed that the dependence of J/{psi} and {psi}{prime} production on nuclear mass number A is very similar. This has been postulated to be due to the predominance of color octet pre-resonant states in charmonium production and absorption. Two new experiments, NA60 at CERN and HERA-B at DESY, will measure the {chi}{sub c} A dependence for the first time. These measurements should shed new light on the charmonium production and absorption mechanisms.
Date: September 24, 2001
Creator: Vogt, R.
System: The UNT Digital Library
Asymmetric PML for the absorption of waves. Application to mesh refinement in electromagnetic particle-in-cell plasma simulations (open access)

Asymmetric PML for the absorption of waves. Application to mesh refinement in electromagnetic particle-in-cell plasma simulations

We present an extension of the Berenger Perfectly Matched Layer with additional terms and tunable coefficients which introduce some asymmetry in the absorption rate. We show that the discretized version of the new PML offers superior absorption rates than the discretized standard PML under a plane wave analysis. Taking advantage of the high rates of absorption of the new PML, we have devised a new strategy for introducing the technique of Mesh Refinement into electromagnetic Particle-In-Cell plasma simulations. We present the details of the algorithm as well as a 2-D example of its application to laser-plasma interaction in the context of fast ignition.
Date: September 24, 2003
Creator: Vay, J. L.; Adam, J. C. & Heron, A.
System: The UNT Digital Library
Autonomous system for pathogen detection and identification (open access)

Autonomous system for pathogen detection and identification

This purpose of this project is to build a prototype instrument that will, running unattended, detect, identify, and quantify BW agents. In order to accomplish this, we have chosen to start with the world� s leading, proven, assays for pathogens: surface-molecular recognition assays, such as antibody-based assays, implemented on a high-performance, identification (ID)-capable flow cytometer, and the polymerase chain reaction (PCR) for nucleic-acid based assays. With these assays, we must integrate the capability to: l collect samples from aerosols, water, or surfaces; l perform sample preparation prior to the assays; l incubate the prepared samples, if necessary, for a period of time; l transport the prepared, incubated samples to the assays; l perform the assays; l interpret and report the results of the assays. Issues such as reliability, sensitivity and accuracy, quantity of consumables, maintenance schedule, etc. must be addressed satisfactorily to the end user. The highest possible sensitivity and specificity of the assay must be combined with no false alarms. Today, we have assays that can, in under 30 minutes, detect and identify simulants for BW agents at concentrations of a few hundred colony-forming units per ml of solution. If the bio-aerosol sampler of this system collects 1000 Ymin …
Date: September 24, 1998
Creator: Belgrader, P.; Benett, W.; Langlois, R.; Long, G.; Mariella, R.; Milanovich, F. et al.
System: The UNT Digital Library
BLV-2011 Workshop, September 22-24, 2011 (open access)

BLV-2011 Workshop, September 22-24, 2011

The 3-rd International 3-days Workshop "Baryon and Lepton Number Violations: BLV-2011" took place at Gatlinburg, TN for September 22-24, 2011. Workshop was organized by the International Organizing Committee and had received advice from the International Program Advisory Committee (see Appendix 1). Workshop was co-chaired by Pavel Fileviez Perez (University of Wisconsin) for theory and Yuri Kamyshkov (University of Tennessee) for experiment and local organization. Workshop was supported and sponsored by the University of Tennessee, Indiana University, North Carolina State University together with TUNL, and by the HEP office of the Department of Energy. DOE financial support in this sponsoring grant was $8,000; that was 23% of the overall budget of the Workshop. Remaining 77% were provided by the sponsoring Universities. Workshop sponsors including DOE are shown on the Workshop webpage. There were 90 workshop participants with 52 from US and remaining from Bosnia/Herzegovina (1), Brazil (1), China (1), Columbia (1), France (1), Germany (10), Italy (9), Japan (4), Russian Federation (3), Slovenia (2), Spain (4), and Switzerland (1). Among Workshop participants there were 17 postdocs and young researchers and 11 graduate students. Total 67 talks and 14 posters were presented at Workshop during 3 days of sessions. Appendix 2 shows …
Date: September 24, 2011
Creator: Committee, Y. A. Kamyshkov (University of Tennessee) co-Chair of the Workshop Organizing; Committee, P. Fileviez Perez (University of Wisconsin) co-Chair of the Workshop Organizing; W. M. Snow (Indiana University), member of Workshop Organizing Committee & A.R. Young (North Carolina State University), member of Workshop Organizing Committee
System: The UNT Digital Library
Bounds and Estimates for Transport Coefficients of Random and Porous Media with High Contrasts (open access)

Bounds and Estimates for Transport Coefficients of Random and Porous Media with High Contrasts

Bounds on transport coefficients of random polycrystals of laminates are presented, including the well-known Hashin-Shtrikman bounds and some newly formulated bounds involving two formation factors for a two-component porous medium. Some new types of self-consistent estimates are then formulated based on the observed analytical structure both of these bounds and also of earlier self-consistent estimates (of the CPA or coherent potential approximation type). A numerical study is made, assuming first that the internal structure (i.e., the laminated grain structure) is not known, and then that it is known. The purpose of this aspect of the study is to attempt to quantify the differences in the predictions of properties of a system being modeled when such organized internal structure is present in the medium but detailed spatial correlation information may or (more commonly) may not be available. Some methods of estimating formation factors from data are also presented and then applied to a high-contrast fluid-permeability data set. Hashin-Shtrikman bounds are found to be very accurate estimates for low contrast heterogeneous media. But formation factor lower bounds are superior estimates for high contrast situations. The new self-consistent estimators also tend to agree better with data than either the bounds or the CPA …
Date: September 24, 2004
Creator: Berger, E. L.
System: The UNT Digital Library
A Camera for Coherent Diffractive Imaging and Holography With a Soft-X-Ray Free Electron Laser (open access)

A Camera for Coherent Diffractive Imaging and Holography With a Soft-X-Ray Free Electron Laser

We describe a camera to record coherent scattering patterns with a soft-X-ray free-electron laser. The camera consists of a laterally-graded multilayer mirror which reflects the diffraction pattern onto a CCD detector. The mirror acts as a bandpass filter both for wavelength and angle, which isolates the desired scattering pattern from non-sample scattering or incoherent emission from the sample. The mirror also solves the particular problem of the extreme intensity of the FEL pulses, which are focused to greater than 10{sup 14} W/cm{sup 2}. The strong undiffracted pulse passes through a hole in the mirror and propagates on to a beam dump at a distance behind the instrument rather than interacting with a beamstop placed near the CCD. The camera concept is extendable for the full range of the fundamental wavelength of the FLASH FEL (i.e. between 6 nm and 60 nm) and into the water window. We have fabricated and tested various multilayer mirrors for wavelengths of 32 nm, 16 nm, 13.5 nm, and 4.5 nm. At the shorter wavelengths mirror roughness must be minimized to reduce scattering from the mirror. We have recorded over 30,000 diffraction patterns at the FLASH free-electron laser with no observable mirror damage or degradation …
Date: September 24, 2007
Creator: Bajt, S.; Chapman, H. N.; Spiller, E.; Alameda, J.; Woods, B.; Frank, M. et al.
System: The UNT Digital Library
Challenges in the Packaging of MEMS (open access)

Challenges in the Packaging of MEMS

Microelectromechanical Systems (MEMS) packaging is much different from conventional integrated circuit (IC) packaging. Many MEMS devices must interface to the environment in order to perform their intended function, and the package must be able to facilitate access with the environment while protecting the device. The package must also not interfere with or impede the operation of the MEMS device. The die attachment material should be low stress, and low outgassing, while also minimizing stress relaxation overtime which can lead to scale factor shifts in sensor devices. The fabrication processes used in creating the devices must be compatible with each other, and not result in damage to the devices. Many devices are application specific requiring custom packages that are not commercially available. Devices may also need media compatible packages that can protect the devices from harsh environments in which the MEMS device may operate. Techniques are being developed to handle, process, and package the devices such that high yields of functional packaged parts will result. Currently, many of the processing steps are potentially harmful to MEMS devices and negatively affect yield. It is the objective of this paper to review and discuss packaging challenges that exist for MEMS systems and to …
Date: September 24, 1999
Creator: BROWN, WILLIAM D.; EATON, WILLIAM P.; MALSHE, AJAY P.; MILLER, WILLIAM M.; O'NEAL, CHAD & SINGH, SUSHILA B.
System: The UNT Digital Library
Chandra HETG Spectra of SS Cyg and U Gem in Quiescence and Outburst (open access)

Chandra HETG Spectra of SS Cyg and U Gem in Quiescence and Outburst

Chandra HETG spectra of the prototypical dwarf novae SS Cyg and U Gem in quiescence and outburst are presented and discussed. When SS Cyg goes into outburst, it becomes dimmer in hard X-rays and displays a dramatic shift in its relative line strengths, whereas when U Gem goes into outburst, it becomes brighter in hard X-rays and displays only a minor shift in its relative line strengths. In both systems, the emission lines become significantly broader in outburst, signaling the presence of high velocity gas either in Keplerian orbits around the white dwarf or flowing outward from the system.
Date: September 24, 2004
Creator: Mauche, C W; Wheatley, P J; Long, K S; Raymond, J C & Szkody, P
System: The UNT Digital Library
Comments on Open-Ended Magnetic Systems for Fusion (open access)

Comments on Open-Ended Magnetic Systems for Fusion

Differentiating characteristics of magnetic confinement systems having externally generated magnetic fields that are open'' are listed and discussed in the light of their several potential advantages for fusion power systems. It is pointed out that at this stage of fusion research high-Q'' (as deduced from long energy confinement times) is not necessarily the most relevant criterion by which to judge the potential of alternate fusion approaches for the economic generation of fusion power. An example is given of a hypothetical open-geometry fusion power system where low-Q operation is essential to meeting one of its main objectives (low neutron power flux).
Date: September 24, 1990
Creator: Post, Richard F.
System: The UNT Digital Library
COMPLETION OF SUPERCONDUCTING MAGNET PRODUCTION AT BNL FOR THE HERA LUMINOSITY UPGRADE (open access)

COMPLETION OF SUPERCONDUCTING MAGNET PRODUCTION AT BNL FOR THE HERA LUMINOSITY UPGRADE

Brookhaven National Laboratory (BNL) has completed production of the superconducting multi-function magnets that are now installed as part of the HERA luminosity upgrade at DESY. The magnets, cryostats, and lead assemblies were designed and built at BNL. To fit inside the existing detectors, the coils plus cryostat structure had to meet a challenging radial budget (e.g., 39 mm horizontally). Two types of magnets were needed and three of each type were built. Each magnet contained normal and skew quadrupole, normal and skew dipole, and sextupole coils. The magnets operate in the {approx}1.5 T solenoid field of a detector. The quadrupole coils produce gradients up to 13 T/m. The dipole coils generate fields up to 0.3 T. Coils were wound under computer control using either seven-strand round cable or a single strand. To simultaneously avoid excessive synchrotron radiation background scattered from the beam pipe and yet have a small cryostat, one type of magnet used a tapered coil structure. The cryogenic system incorporates cooling with both 40 K helium and supercritical helium. All of the coils were tested in liquid helium in a vertical dewar. Quench test results have been excellent. The field quality of the magnets has met the stringent …
Date: September 24, 2001
Creator: WANDERER,P. ANERELLA,M. ESCALLIER,J. GHOSH,A. JAIN,A. MARONE,A. MURATORE,J. PARKER,A. PRODELL,A. THOMPSON,P. WU,K. C.
System: The UNT Digital Library
Computational studies of two-component mirror reactors (open access)

Computational studies of two-component mirror reactors

None
Date: September 24, 1974
Creator: Byers, J. A.; Freis, R. P.; Killeen, J.; Lee, E. P.; McNamara, B.; Mirin, A. A. et al.
System: The UNT Digital Library
Conceptual Design of Pion Capture Magnets of Up to 15 Cm Bore and 20 T Peak Field. (open access)

Conceptual Design of Pion Capture Magnets of Up to 15 Cm Bore and 20 T Peak Field.

For the Neutrino Factory and Muon Collider Collaboration, BNL has considered solenoidal magnet systems of several types to capture pions generated by bombarding a mercury jet with multi-GeV protons. The magnet systems generate up to 20 T, uniform to 5% throughout a cylindrical volume 0.15 m in diameter and 0.6 m long. Axially downstream the field ramps gradually downward by a factor of sixteen, while the bore increases fourfold. The steady-state system needed for an accelerator has many superconducting coils and a radiation-resistant insert of mineral-insulated hollow conductor. Less costly, pulsed systems suffice to study pion capture and the effect of a magnetic field on a jet hit by a proton beam. BNL has explored three types of magnets, each with its principal coils precooled by liquid nitrogen. One type employs two sets of coils energized sequentially. Charged in 23 s by a power supply of 5 MVA, the 16ton outer set generates 10 T and stores 28 MJ, from which, in 1/3 s, to charge a half-ton inner coil that adds 12 1/2 T to the 7 1/2 T remaining from the outer set. An alternative design uses 25 MVA to energize, in 1.4 s, a single 3-ton set …
Date: September 24, 2001
Creator: Weggel, R. J.
System: The UNT Digital Library
Convective oxygen transport during development in embryos of the snapping turtle Chelydra serpentina (open access)

Convective oxygen transport during development in embryos of the snapping turtle Chelydra serpentina

This article describes a study investigating the maturation of convective oxygen transport in embryos of the snapping turtle (Chelydra serpentina). Measurements included: mass, oxygen consumption, heart rate, blood oxygen content and affinity and blood flow distribution at 50%, 70% and 90% of the incubation period.
Date: September 24, 2018
Creator: Sartori, Marina R.; Kohl, Zachary F.; Taylor, Edwin W.; Abe, Augusto S. & Crossley, Dane A., II
System: The UNT Digital Library
Corrosion Evaluation of Aluminum Alloys in Deionized Water (open access)

Corrosion Evaluation of Aluminum Alloys in Deionized Water

Spent nuclear fuels from foreign and domestic research and test reactors being returned to SRS are now stored with other nuclear materials in the L-basin at the Savannah River Site (SRS). Recent efforts have consolidated the fuel storage systems and L-basin has become the SRS site for water storage of spent nuclear fuels. Corrosion surveillance of coupons in this basin is being performed to provide assurance of safe storage of spent fuel. This paper describes the highlights of recent studies on these aluminum coupons after immersion for more than 7 years in L-basin. Selected coupons were metallurgically characterized to establish the existence of general corrosion and pitting. Pitting was observed on galvanically coupled samples and also on intentionally creviced coupons, thus demonstrating that localized concentration cells were formed during the exposure period. In these cases, the susceptibility to pitting was not attributed to aggressive basin water chemistry but to local condition s (crevices and galvanic coupling) that allowed the development of oxygen and/or metal ion concentration cells that produced locally aggressive waters. General corrosion was also observed on some of the coupons that had not been treated to enhance the protective oxide prior to exposure in the basin water. These …
Date: September 24, 2004
Creator: Vormelker, Philip R. & Duncan, Andrew J.
System: The UNT Digital Library
CP Violation in B0 decays to Charmonium and Charm Final States (open access)

CP Violation in B0 decays to Charmonium and Charm Final States

We report on measurements of time-dependent CP-violation asymmetries in neutral B meson decays to charmonium and charm final states. The results are obtained from a data sample of (467 {+-} 5) x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II B factory.
Date: September 24, 2008
Creator: Chen, Chunhui
System: The UNT Digital Library
A Decade of NSTX Operations Using Collaborative Software (open access)

A Decade of NSTX Operations Using Collaborative Software

Since the beginning of the National Spherical Torus Experiment's (NSTX) research activities in 1999, open-source and collaborative software have been used extensively for experimental operations. The software included Experimental Physics and Industrial Control System (EPICS) and the Model Data System plus (MDSplus). This paper will begin with a retrospective of ten years of integrated computing, control, and data analysis on NSTX. A variety of practical issues will be reviewed such as: system reliability, availability, and maintainability; using open source software with commercialoff- the-shelf (COTS) hardware; obsolescence and remaining current. Recent improvements, current status, and emerging issues will be presented. Numerous proposals for NSTX upgrades have been made that will extend the performance and operating lifetime of NSTX. In light of this, a collective strategy for improving NSTX's collaborative software model for a new decade of operations will be examined.
Date: September 24, 2009
Creator: P. Sichta, W. Davis, J. Dong, D. Mastrovito, G. Tchilinguirian, G. Zimmer
System: The UNT Digital Library