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Use of High Resolution DAQ System to Aid Diagnosis of HD2b, a High Performance Nb3Sn Dipole

Description: A novel voltage monitoring system to record voltage transients in superconducting magnets is being developed at LBNL. This system has 160 monitoring channels capable of measuring differential voltages of up to 1.5kV with 100kHz bandwidth and 500kS/s digitizing rate. This paper presents analysis results from data taken with a 16 channel prototype system. From that analysis we were able to diagnose a change in the current-temperature margin of the superconducting cable by analyzing Flux-Jump data collected after a magnet energy extraction failure during testing of a high field Nb{sub 3}Sn dipole.
Date: August 17, 2008
Creator: Lizarazo, J.; Doering, D.; Doolittle, L.; Galvin, J.; Caspi, S.; Dietderich, D. R. et al.
Partner: UNT Libraries Government Documents Department

Design of a Nb3Sn Magnet for a 4th Generation ECR Ion Source

Description: The next generation of Electron Cyclotron Resonant (ECR) ion sources are expected to operate at a heating radio frequency greater than 40 GHz. The existing 3rd generation systems, exemplified by the state of the art system VENUS, operate in the 10-28 GHz range, and use NbTi superconductors for the confinement coils. The magnetic field needed to confine the plasma scales with the rf frequency, resulting in peak fields on the magnets of the 4th generation system in excess of 10 T. High field superconductors such as Nb{sub 3}Sn must therefore be considered. The magnetic design of a 4th. generation ECR ion source operating at an rf frequency of 56 GHz is considered. The analysis considers both internal and external sextupole configurations, assuming commercially available Nb{sub 3}Sn material properties. Preliminary structural design issues are discussed based on the forces and margins associated with the coils in the different configurations, leading to quantitative data for the determination of a final magnet design.
Date: August 17, 2008
Creator: Prestemon, S,; Trillaud, F.; Caspi, S.; Ferracin, P.; Sabbi, G. L.; Lyneis, C. M. et al.
Partner: UNT Libraries Government Documents Department

Novel Method for Growing Te-Inclusion-Free CZT

Description: The authors propose a new method for growth of detector-grade CdZnTe (CZT) with reduced concentration and sizes of Te inclusions. The method is designed to impede the formation of Te-rich inclusions in crystals due to the use of new CZT growth method and a unique ampoule design.
Date: June 17, 2008
Creator: Bolotnikov, A.
Partner: UNT Libraries Government Documents Department

Development of Room-temperature CdMnTe Gamma-ray Detectors

Description: CdMnTe materials have wide bandgap, high resistivity, fair electron-transport properties, and good compositional uniformity. All these features make CdMnTe a good candidate for low cost, high-resolution room-temperature gamma-ray detector. Using several techniques available at BNL, we are characterizing CdMnTe as a material for gamma-ray detectors. The consequent improvements in growth, fabrication, and manufacturing techniques for CdMnTe potentially yield a suitable material for sensing devices with lower production costs. Success of this research has the possibility of generating high impact to nuclear nonproliferation with the goal of offering inexpensive highly sensitive gamma spectrometers.
Date: June 17, 2008
Creator: Bolotnikov, A.
Partner: UNT Libraries Government Documents Department

Thermal neutron imaging support with other laboratories BL06-IM-TNI

Description: The goals of this project are: (1) detect and locate a source of thermal neutrons; (2) distinguish a localized source from uniform background; (3) show shape and size of thermalizing material; (4) test thermal neutron imager in active interrogation environment; and (5) distinguish delayed neutrons from prompt neutrons.
Date: June 17, 2008
Creator: Vanier, P. E.
Partner: UNT Libraries Government Documents Department

Imaging Single ZnO Vertical Nanowire Laser Cavities using UV-Laser Scanning Confocal Microscopy

Description: We report the fabrication and optical characterization of individual ZnO vertical nanowire laser cavities. Dilute nanowire arrays with interwire spacing>10 ?m were produced by a modified chemical vapor transport (CVT) method yielding an ideal platform for single nanowire imaging and spectroscopy. Lasing characteristics of a single vertical nanowire are presented, as well as high-resolution photoluminescence imaging by UV-laser scanning confocal microscopy. In addition, three-dimensional (3D) mapping of the photoluminescence emission performed in both planar and vertical dimensions demonstrates height-selective imaging useful for vertical nanowires and heteronanostructures emerging in the field of optoelectronics and nanophotonics.
Date: November 17, 2008
Creator: Gargas, D.J.; Toimil-Molares, M.E. & Yang, P.
Partner: UNT Libraries Government Documents Department

Metrologies for the Phase Characterization of Attosecond

Description: EUV optics play a key role in attosecond science since only with higher photon energies is it possible to achieve the wide spectral bandwidth required for ultrashort pulses. Multilayer EUV mirrors have been proposed and are being developed to temporally shape (compress) attosecond pulses. To fully characterize a multilayer optic for pulse applications requires not only knowledge of the reflectivity, as a function of photon energy, but also the reflected phase of the mirror. This work develops the metrologies to determine the reflected phase of an EUV multilayer mirror using the photoelectric effect. The proposed method allows one to determine the optic's impulse response and hence its pulse characteristics.
Date: January 17, 2008
Creator: CXRO
Partner: UNT Libraries Government Documents Department

Parallel Simulation Algorithms for the Three Dimensional Strong-Strong Beam-Beam Interaction

Description: The strong-strong beam-beam effect is one of the most important effects limiting the luminosity of ring colliders. Little is known about it analytically, so most studies utilize numeric simulations. The two-dimensional realm is readily accessible to workstation-class computers (cf.,e.g.,[1, 2]), while three dimensions, which add effects such as phase averaging and the hourglass effect, require vastly higher amounts of CPU time. Thus, parallelization of three-dimensional simulation techniques is imperative; in the following we discuss parallelization strategies and describe the algorithms used in our simulation code, which will reach almost linear scaling of performance vs. number of CPUs for typical setups.
Date: March 17, 2008
Creator: Kabel, A. C.
Partner: UNT Libraries Government Documents Department

Initial State Radiation Physics at the B Factories

Description: A mini-review of the recent BaBar and Belle results on the process e{sup +}e{sup -} {yields} hadrons using the initial state radiation (ISR) technique, is presented. ISR studies at the {Upsilon}(4s) resonance (B-Factories) can yield to the same observables as the low energy e{sup +}e{sup -} experiments: Precise cross-section measurements, the R ratio (ratio of cross-sections of hadron production to di-muon production) measurement, form factors measurements (from hadron pair production such as e{sup +}e{sup -} {yields} p{bar p}, {Lambda}{bar {Lambda}}, {Lambda}{bar {Sigma}}, {Sigma}{bar {Sigma}}), as well as J{sup PC} = 1{sup --} hadron spectroscopy that can lead to the discovery of new states.
Date: June 17, 2008
Creator: Grauges, Eugeni
Partner: UNT Libraries Government Documents Department

Breakdown Limits on Gigavolt-per-Meter Electron-Beam-Driven Wakefields in Dielectric Structures

Description: First measurements of the breakdown threshold in a dielectric subjected to GV/m wakefields produced by short (30-330 fs), 28.5 GeV electron bunches have been made. Fused silica tubes of 100 {micro}m inner diameter were exposed to a range of bunch lengths, allowing surface dielectric fields up to 27 GV/m to be generated. The onset of breakdown, detected through light emission from the tube ends, is observed to occur when the peak electric field at the dielectric surface reaches 13.8 {+-} 0.7 GV/m. The correlation of structure damage to beam-induced breakdown is established using an array of postexposure inspection techniques.
Date: June 17, 2008
Creator: Thompson, M. C.; Badakov, H.; Cook, A. M.; Rosenzweig, J. B.; Tikhoplav, R.; Travish, G. et al.
Partner: UNT Libraries Government Documents Department

Design of an Optical Diffraction Radiation Beam Size Monitor at SLAC FETB

Description: We design a single bunch transverse beam size monitor which will be tested to measure the 28.5 GeV electron/positron beam at the SLAC FFTB beam line. The beam size monitor uses the CCD images of the interference pattern of the optical diffraction radiation from two slit edges which are placed close to the beam path. In this method, destruction of the accelerated electron/positron beam bunches due to the beam size monitoring is negligible, which is vital to the operation of the Linear Collider project.
Date: March 17, 2008
Creator: Fukui, Yasuo; Cline, D.; Zhou, F.; Tobiyama, M.; Urakawa, J.; Bolton, P. R. et al.
Partner: UNT Libraries Government Documents Department

A Parallel Code for Lifetime Simulations in Hadron Storage Rings in the Presence of Parasitic Beam-Beam Interactions

Description: The usual approach to predict particle loss in storage rings in the presence of nonlinearities consists in the determination of the dynamic aperture of the machine. This method, however, will not directly predict the lifetimes of beams. We have developed a code which can, by parallelization and careful speed optimization, predict lifetimes in the presence of 100 parasitic beam-beam crossings by tracking > 10{sup 10} particles-turns. An application of this code to the anti-proton lifetime in the Tevatron at injection is discussed.
Date: March 17, 2008
Creator: Kabel, A. C.; Cai, Y.; Erdelyi, B.; Sen, T. & Xiao, M.
Partner: UNT Libraries Government Documents Department

Electron Cloud Mitigation in the Spallation Neutron Source Ring

Description: The Spallation Neutron Source (SNS) accumulator ring is designed to accumulate, via H{sup -} injection, protons of 2 MW beam power at 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity, electron-cloud is expected to be one of the intensity-limiting mechanisms that complicate ring operations. This paper summarizes mitigation strategy adopted in the design, both in suppressing electron-cloud formation and in enhancing Landau damping, including tapered magnetic field and monitoring system for the collection of stripped electrons at injection, TiN coated beam chamber for suppression of the secondary yield, clearing electrodes dedicated for the injection region and parasitic on BPMs around the ring, solenoid windings in the collimation region, and planning of vacuum systems for beam scrubbing upon operation.
Date: March 17, 2008
Creator: Wei, J.; Blaskiewicz, Michael; Brodowski, J.; Cameron, P.; Davino, Daniele; Fedotov, A. et al.
Partner: UNT Libraries Government Documents Department

Environmental genomics reveals a single species ecosystem deep within the Earth

Description: DNA from low biodiversity fracture water collected at 2.8 km depth in a South African gold mine was sequenced and assembled into a single, complete genome. This bacterium, Candidatus Desulforudis audaxviator, comprises>99.9percent of the microorganisms inhabiting the fluid phase of this particular fracture. Its genome indicates a motile, sporulating, sulfate reducing, chemoautotrophic thermophile that can fix its own nitrogen and carbon using machinery shared with archaea. Candidatus Desulforudis audaxviator is capable of an independent lifestyle well suited to long-term isolation from the photosphere deep within Earth?s crust, and offers the first example of a natural ecosystem that appears to have its biological component entirely encoded within a single genome.
Date: September 17, 2008
Creator: Chivian, Dylan; Brodie, Eoin L.; Alm, Eric J.; Culley, David E.; Dehal, Paramvir S.; DeSantis, Todd Z. et al.
Partner: UNT Libraries Government Documents Department

Numerical studies of fluid-rock interactions in EnhancedGeothermal Systems (EGS) with CO2 as working fluid

Description: There is growing interest in the novel concept of operating Enhanced Geothermal Systems (EGS) with CO{sub 2} instead of water as heat transmission fluid. Initial studies have suggested that CO{sub 2} will achieve larger rates of heat extraction, and can offer geologic storage of carbon as an ancillary benefit. Fluid-rock interactions in EGS operated with CO{sub 2} are expected to be vastly different in zones with an aqueous phase present, as compared to the central reservoir zone with anhydrous supercritical CO{sub 2}. Our numerical simulations of chemically reactive transport show a combination of mineral dissolution and precipitation effects in the peripheral zone of the systems. These could impact reservoir growth and longevity, with important ramifications for sustaining energy recovery, for estimating CO{sub 2} loss rates, and for figuring tradeoffs between power generation and geologic storage of CO{sub 2}.
Date: January 17, 2008
Creator: Xu, Tianfu; Pruess, Karsten & Apps, John
Partner: UNT Libraries Government Documents Department

Proceedings of RIKEN BNL Research Center Workshop, Volume 91, RBRC Scientific Review Committee Meeting

Description: The ninth evaluation of the RIKEN BNL Research Center (RBRC) took place on Nov. 17-18, 2008, at Brookhaven National Laboratory. The members of the Scientific Review Committee (SRC) were Dr. Dr. Wit Busza (Chair), Dr. Miklos Gyulassy, Dr. Akira Masaike, Dr. Richard Milner, Dr. Alfred Mueller, and Dr. Akira Ukawa. We are pleased that Dr. Yasushige Yano, the Director of the Nishina Institute of RIKEN, Japan participated in this meeting both in informing the committee of the activities of the Nishina Institute and the role of RBRC and as an observer of this review. In order to illustrate the breadth and scope of the RBRC program, each member of the Center made a presentation on his/her research efforts. This encompassed three major areas of investigation, theoretical, experimental and computational physics. In addition the committee met privately with the fellows and postdocs to ascertain their opinions and concerns. Although the main purpose of this review is a report to RIKEN Management (Dr. Ryoji Noyori, RIKEN President) on the health, scientific value, management and future prospects of the Center, the RBRC management felt that a compendium of the scientific presentations are of sufficient quality and interest that they warrant a wider distribution. Therefore we have made this compilation and present it to the community for its information and enlightenment.
Date: November 17, 2008
Creator: Samios,N.P.
Partner: UNT Libraries Government Documents Department

Shaping metal nanocrystals through epitaxial seeded growth

Description: Morphological control of nanocrystals has becomeincreasingly important, as many of their physical and chemical propertiesare highly shape-dependent. Nanocrystal shape control for both single andmultiple material systems, however, remains fairly empirical andchallenging. New methods need to be explored for the rational syntheticdesign of heterostructures with controlled morphology. Overgrowth of adifferent material on well-faceted seeds, for example, allows for the useof the defined seed morphology to control nucleation and growth of thesecondary structure. Here, we have used highly faceted cubic Pt seeds todirect the epitaxial overgrowth of a secondary metal. We demonstrate thisconcept with lattice matched Pd to produce conformal shape-controlledcore-shell particles, and then extend it to lattice mismatched Au to giveanisotropic growth. Seeding with faceted nanocrystals may havesignificant potential towards the development of shape-controlledheterostructures with defined interfaces.
Date: February 17, 2008
Creator: Habas, Susan E.; Lee, Hyunjoo; Radmilovic, Velimir; Somorjai,Gabor A. & Yang, Peidong
Partner: UNT Libraries Government Documents Department

BIOGEOCHEMICAL GRADIENTS AS A FRAMEWORK FOR UNDERSTANDING WASTE SITE EVOLUTION

Description: The migration of biogeochemical gradients is a useful framework for understanding the evolution of biogeochemical conditions in groundwater at waste sites contaminated with metals and radionuclides. This understanding is critical to selecting sustainable remedies and evaluating sites for monitored natural attenuation, because most attenuation mechanisms are sensitive to geochemical conditions such as pH and redox potential. Knowledge of how gradients in these parameters evolve provides insights into the behavior of contaminants with time and guides characterization, remedy selection, and monitoring efforts. An example is a seepage basin site at the Savannah River Site in South Carolina where low-level acidic waste has seeped into groundwater. The remediation of this site relies, in part, on restoring the natural pH of the aquifer by injecting alkaline solutions. The remediation will continue until the pH up-flow of the treatment zone increases to an acceptable value. The time required to achieve this objective depends on the time it takes the trailing pH gradient, the gradient separating the plume from influxing natural groundwater, to reach the treatment zone. Predictions of this length of time will strongly influence long-term remedial decisions.
Date: October 17, 2008
Creator: Denham, M. & Karen Vangelas, K.
Partner: UNT Libraries Government Documents Department

Test Results of LARP 3.6 m Nb3Sn Racetrack Coils Support by Full-length and Segmented Shell Structures

Description: As part of the LHC Accelerator Research Program (LARP) to build a high performance quadrupole magnet with Nb{sub 3}Sn conductor, a pair of 3.6 m-long Nb{sub 3}Sn racetrack coils has been made at Brookhaven National Laboratory (BNL) and installed in two shell-type support structures built by Lawrence Berkeley National Laboratory (LBL). These magnet assemblies have been tested at 4.5 K at BNL to gauge the effect of extended length and prestress on the mechanical performance of the long structure compared to earlier short models. This paper presents the results of quench testing and compares the overall performance of the two versions of the support structure. We also summarize the shell strain measurements and discuss the variation of quench current with ramp rate.
Date: August 17, 2008
Creator: Muratore, Joseph F.; Ambrosio, Giorgio; Anerella, Michael; Barzi, Emanuela; Bossert, Rodger; Caspi, Shlomo et al.
Partner: UNT Libraries Government Documents Department

Test Results of LARP Nb3Sn Quadrupole Magnets Using a Shell-based Support Structure (TQS)

Description: Among the magnet development program of a large-aperture Nb{sub 3}Sn superconducting quadrupole for the Large Hadron Collider luminosity upgrade, six quadrupole magnets were built and tested using a shell based key and bladder technology (TQS). The 1 m long 90 mm aperture magnets are part o fthe US LHC Accelerator Research Program (LARP) aimed at demonstrating Nb{sub 3}Sn technology by the year 2009, of a 3.6 m long magnet capable of achieving 200 T/m. In support of the LARP program the TQS magnets were tested at three different laboratories, LBNL, FNAL and CERN and while at CERN a technology-transfer and a four days magnet disassembly and reassembly were included. This paper summarizes the fabrication, assembly, cool-down and test results of the six magnets and compres measruements with design expectations.
Date: August 17, 2008
Creator: Caspi, S.; Dietderich, D. R.; Felice, H.; Ferracin, P.; Hafalia, R.; Hannaford, C. R. et al.
Partner: UNT Libraries Government Documents Department