MPI Runtime Error Detection with MUST: Advances in Deadlock Detection (open access)

MPI Runtime Error Detection with MUST: Advances in Deadlock Detection

None
Date: May 4, 2012
Creator: Hilbrich, T; Protze, J; Schulz, M; de Supinski, B & Mueller, M
Object Type: Article
System: The UNT Digital Library
Measurements of the Persistent Current Decay and Snapback Effect in Nb3Sn Accelerator Prototype Magnets at Fermilab (open access)

Measurements of the Persistent Current Decay and Snapback Effect in Nb3Sn Accelerator Prototype Magnets at Fermilab

None
Date: May 1, 2012
Creator: Velev, G.V.; Chlachidze, G.; DiMarco, J.; Kashikhin, V.V. & /Fermilab
Object Type: Article
System: The UNT Digital Library
Commissioning of a beta* knob for dynamic IR correction at RHIC (open access)

Commissioning of a beta* knob for dynamic IR correction at RHIC

In addition to the recent optics correction technique demonstrated at CERN and applied at RHIC, it is important to have a separate tool to control the value of the beta functions at the collision point ({beta}*). This becomes even more relevant when trying to reach high level of integrated luminosity while dealing with emittance blow-up over the length of a store, or taking advantage of compensation processes like stochastic cooling. Algorithms have been developed to allow modifying independently the beta function in each plane for each beam without significant increase in beam losses. The following reviews the principle of such algorithms and their experimental implementation as a dynamic {beta}-squeeze procedure.
Date: May 20, 2012
Creator: G., Robert-Demolaize; Marusic, A.; Tepikian, S. & White, S.
Object Type: Article
System: The UNT Digital Library
Coalescing at 8 GeV in the Fermilab Main Injector (open access)

Coalescing at 8 GeV in the Fermilab Main Injector

For Project X, it is planned to inject a beam of 3 10{sup 11} particles per bunch into the Main Injector. To prepare for this by studying the effects of higher intensity bunches in the Main Injector it is necessary to perform coalescing at 8 GeV. The results of a series of experiments and simulations of 8 GeV coalescing are presented. To increase the coalescing efficiency adiabatic reduction of the 53 MHz RF is required. This results in {approx}70% coalescing efficiency of 5 initial bunches. Data using wall current monitors has been taken to compare previous work and new simulations for 53 MHz RF reduction, bunch rotations and coalescing, good agreement between experiment and simulation was found. By increasing the number of bunches to 7 and compressing the bunch energy spread a scheme generating approximately 3 10{sup 11} particles in a bunch has been achieved. These bunches will then be used in further investigations.
Date: May 1, 2012
Creator: Scott, D. J.; Capista, D.; Chase, B.; Dye, J.; Kourbanis, I.; Seiya, K. et al.
Object Type: Article
System: The UNT Digital Library
Experimental Study of Parametric Dependence of Electron-scale Turbulence in a Spherical Tokamak (open access)

Experimental Study of Parametric Dependence of Electron-scale Turbulence in a Spherical Tokamak

Electron-scale turbulence is predicted to drive anomalous electron thermal transport. However, experimental study of its relation with transport is still in its early stage. On the National Spherical Tokamak eXperiment (NSTX), electron-scale density fluctuations are studied with a novel tangen- tial microwave scattering system with high radial resolution of ±2 cm. Here, we report a study of parametric dependence of electron-scale turbulence in NSTX H-mode plasmas. The dependence on density gradient is studied through the observation of a large density gradient variation in the core induced by an ELM event, where we found the first clear experimental evidence of density gradient stabilization of electron-gyro scale turbulence in a fusion plasma. This observation, cou- pled with linear gyro-kinetic calculations, leads to the identification of the observed instability as toroidal Electron Temperature Gradient (ETG) modes. It is observed that longer wavelength ETG modes, k⊥ρs < 10 (ρs is the ion gyroradius at electron temperature and k⊥ is the wavenumber perpendicular to local equilibrium magnetic field), are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in electron thermal diffusivity. Comparisons with nonlinear ETG gyrokinetic simulations shows ETG turbulence may be able to explain the …
Date: May 23, 2012
Creator: Ren, Y.; Kaye, S. M.; Mazzucato, E.; Bell, R. E.; Diallo, A.; Domier, C. W. et al.
Object Type: Report
System: The UNT Digital Library
Single/Few Bunch Space Charge Effects at 8 GeV in the Fermilab Main Injector (open access)

Single/Few Bunch Space Charge Effects at 8 GeV in the Fermilab Main Injector

For Project X, it is planned to inject a beam of 3 10{sup 11} particles per bunch into the Main Injector. Therefore, at 8 GeV, there will be increased space charge tune shifts and an increased incoherent tune spread. In preparation for these higher intensity bunches exploratory studies have commenced looking at the transmission of different intensity bunches at different tunes. An experiment is described with results for bunch intensities between 20 and 300 10{sup 9} particles. To achieve the highest intensity bunches coalescing at 8 GeV is required, resulting in a longer bunch length. Comparisons show that similar transmission curves are obtained when the intensity and bunch length have increased by similar factors. This indicates the incoherent tune shifts are similar, as expected from theory. The results of these experiments will be used in conjugation with simulations to further study high intensity bunches in the Main Injector.
Date: May 1, 2012
Creator: Scott, D. J.; Capista, D.; Kourbanis, I.; Seiya, K. & Yang, M. J.
Object Type: Article
System: The UNT Digital Library
Bunch compressor design for potential FEL operation at eRHIC (open access)

Bunch compressor design for potential FEL operation at eRHIC

N/A
Date: May 20, 2012
Creator: Y., Jing; Hao, Y. & Litvinenko, V.
Object Type: Article
System: The UNT Digital Library
Concept of Operations for Nuclear Warhead Embedded Sensors (open access)

Concept of Operations for Nuclear Warhead Embedded Sensors

Embedded arms-control-sensors provide a powerful new paradigm for managing compliance with future nuclear weapons treaties, where deployed warhead numbers will be reduced to 1000 or less. The CONOPS (Concept of Operations) for use with these sensors is a practical tool with which one may help define design parameters, including size, power, resolution, communications, and physical structure. How frequently must data be acquired and must a human be present? Will such data be acquired for only stored weapons or will it be required of deployed weapons as well? Will tactical weapons be subject to such monitoring or will only strategic weapons apply? Which data will be most crucial? Will OSI's be a component of embedded sensor data management or will these sensors stand alone in their data extraction processes? The problem space is massive, but can be constrained by extrapolating to a reasonable future treaty regime and examining the bounded options this scenario poses. Arms control verification sensors, embedded within the warhead case or aeroshell, must provide sufficient but not excessively detailed data, confirming that the item is a nuclear warhead and that it is a particular warhead without revealing sensitive information. Geolocation will be provided by an intermediate transceiver used …
Date: May 16, 2012
Creator: Rockett, P. D. & Koncher, T. R.
Object Type: Report
System: The UNT Digital Library
Tailoring properties of carbon-nanotube-based foams by ion bombardment (open access)

Tailoring properties of carbon-nanotube-based foams by ion bombardment

None
Date: May 17, 2012
Creator: Charnvanichborikarn, S.; Shin, S. J.; Worsley, M. A. & Kucheyev, S. O.
Object Type: Article
System: The UNT Digital Library
Second Line of Defense, Megaports Initiative, Operational Testing and Evaluation Plan, Port of Lazaro Cardenas, Mexico (open access)

Second Line of Defense, Megaports Initiative, Operational Testing and Evaluation Plan, Port of Lazaro Cardenas, Mexico

The purpose of the Operational Testing and Evaluation (OT&E) phases of the project is to prepare for turnover of the Megaports System supplied by U.S. Department of Energy/National Nuclear Security Administration (DOE/NNSA)—located at the Export Lanes of the Port of Lazaro Cardenas, Mexico—to the Government of Mexico (GOM).
Date: May 30, 2012
Creator: Hughes, Jamie D.
Object Type: Report
System: The UNT Digital Library
Ultracompact Accelerator Technology for a Next-Generation Gamma-Ray Source (open access)

Ultracompact Accelerator Technology for a Next-Generation Gamma-Ray Source

This presentation reported on the technology choices and progress manufacturing and testing the injector and accelerator of the 250 MeV ultra-compact Compton Scattering gamma-ray Source under development at LLNL for homeland security applications. This paper summarizes the status of various facets of current accelerator activities at LLNL. The major components for the X-band test station have been designed, fabricated, and await installation. The XL-4 klystron has been delivered, and will shortly be dressed and installed in the ScandiNova modulator. High power testing of the klystron into RF loads will follow, including adjustment of the modulator for the klystron load as necessary. Assembly of RF transport, test station supports, and accelerator components will follow. Commissioning will focus on processing the RF gun to full operating power, which corresponds to 200 MV/m peak electric field on the cathode surface. Single bunch benchmarking of the Mark 1 design will provide confidence that this first structure operates as designed, and will serve as a solid starting point for subsequent changes, such as a removable photocathode, and the use of various cathode materials for enhanced quantum efficiency. Charge scaling experiments will follow, partly to confirm predictions, as well as to identify important causes of emittance …
Date: May 14, 2012
Creator: Marsh, R A; Albert, F; Anderson, S G; Gibson, D J; Wu, S S; Hartemann, F V et al.
Object Type: Article
System: The UNT Digital Library
Sequestration and Enhanced Coal Bed Methane: Tanquary Farms Test Site, Wabash County, Illinois (open access)

Sequestration and Enhanced Coal Bed Methane: Tanquary Farms Test Site, Wabash County, Illinois

The Midwest Geological Sequestration Consortium (MGSC) carried out a pilot project to test storage of carbon dioxide (CO{sub 2}) in the Springfield Coal Member of the Carbondale Formation (Pennsylvanian System), in order to gauge the potential for large-scale CO{sub 2} sequestration and/or enhanced coal bed methane recovery from Illinois Basin coal beds. The pilot was conducted at the Tanquary Farms site in Wabash County, southeastern Illinois. A four-well design— an injection well and three monitoring wells—was developed and implemented, based on numerical modeling and permeability estimates from literature and field data. Coal cores were taken during the drilling process and were characterized in detail in the lab. Adsorption isotherms indicated that at least three molecules of CO{sub 2} can be stored for each displaced methane (CH{sub 4}) molecule. Microporosity contributes significantly to total porosity. Coal characteristics that affect sequestration potential vary laterally between wells at the site and vertically within a given seam, highlighting the importance of thorough characterization of injection site coals to best predict CO{sub 2} storage capacity. Injection of CO{sub 2} gas took place from June 25, 2008, to January 13, 2009. A “continuous” injection period ran from July 21, 2008, to December 23, 2008, but injection …
Date: May 1, 2012
Creator: Frailey, Scott; Parris, Thomas; Damico, James; Okwen, Roland; McKaskle, Ray; Monson, Charles et al.
Object Type: Report
System: The UNT Digital Library
Secondary Electron Yield Measurements of Fermilab's Main Injector Vacuum Vessel (open access)

Secondary Electron Yield Measurements of Fermilab's Main Injector Vacuum Vessel

We discuss the progress made on a new installation in Fermilab's Main Injector that will help investigate the electron cloud phenomenon by making direct measurements of the secondary electron yield (SEY) of samples irradiated in the accelerator. In the Project X upgrade the Main Injector will have its beam intensity increased by a factor of three compared to current operations. This may result in the beam being subject to instabilities from the electron cloud. Measured SEY values can be used to further constrain simulations and aid our extrapolation to Project X intensities. The SEY test-stand, developed in conjunction with Cornell and SLAC, is capable of measuring the SEY from samples using an incident electron beam when the samples are biased at different voltages. We present the design and manufacture of the test-stand and the results of initial laboratory tests on samples prior to installation.
Date: May 1, 2012
Creator: Scott, D. J.; Capista, D.; Duel, K. L.; Zwaska, R. M.; Greenwald, S.; Hartung, W. et al.
Object Type: Article
System: The UNT Digital Library
Influence of Intense Beam in High Pressure Hydrogen Gas Filled RF Cavities (open access)

Influence of Intense Beam in High Pressure Hydrogen Gas Filled RF Cavities

The influence of an intense beam in a high-pressure gas filled RF cavity has been measured by using a 400 MeV proton beam in the Mucool Test Area at Fermilab. The ionization process generates dense plasma in the cavity and the resultant power loss to the plasma is determined by measuring the cavity voltage on a sampling oscilloscope. The energy loss has been observed with various peak RF field gradients (E), gas pressures (p), and beam intensities in nitrogen and hydrogen gases. Observed RF energy dissipation in single electron (dw) in N{sub 2} and H{sub 2} gases was 2 10{sup -17} and 3 10{sup -17} Joules/RF cycle at E/p = 8 V/cm/Torr, respectively. More detailed dw measurement have been done in H{sub 2} gas at three different gas pressures. There is a clear discrepancy between the observed dw and analytical one. The discrepancy may be due to the gas density effect that has already been observed in various experiments.
Date: May 1, 2012
Creator: Yonehara, K.; Chung, M.; Collura, M. G.; Jana, M. R.; Leonova, M.; Moretti, A. et al.
Object Type: Article
System: The UNT Digital Library
Coherent beam-beam effects observation and mitigation at the RHIC collider (open access)

Coherent beam-beam effects observation and mitigation at the RHIC collider

In polarized proton operation in RHIC coherent beam-beam modes are routinely observed with beam transfer function measurements in the vertical plane. With the existence of coherent modes a larger space is required in the tune diagram than without them and stable conditions can be compromised for operation with high intensity beams as foreseen for future luminosity upgrades. We report on experiments and simulations carried out to understand the existence of coherent modes in the vertical plane and their absence in the horizontal plane, and investigate possible mitigation strategies.
Date: May 20, 2012
Creator: S., White; Fischer, W. & Luo, Y.
Object Type: Article
System: The UNT Digital Library
Advanced Metal-Hydrides-Based Thermal Battery (open access)

Advanced Metal-Hydrides-Based Thermal Battery

Advanced Research Projects Agency-Energy project sheet summarizing general information about the High Energy Advanced Thermal Storage (HEATS) program including critical needs, innovation and advantages, impacts, and contact information. This sheet discusses an advanced metal-hydrides-based thermal battery as part of the "A New Generation of High Density Thermal Battery Based on Advanced Metal Hydrides" project.
Date: May 25, 2012
Creator: University of Utah
Object Type: Text
System: The UNT Digital Library
Comparing new models of transverse instability with simulations (open access)

Comparing new models of transverse instability with simulations

Recently, Balbekov and Burov have produced an ordinary integro-differential equation that approximates the Vlasov equation for beams with wakefields and large space charge tune shift. The present work compares this model with simulations. In particular, the claim that certain types of transverse wakes cannot lead to mode coupling instabilities is explored.
Date: May 20, 2012
Creator: M., Blaskiewicz
Object Type: Article
System: The UNT Digital Library
Optics measurements and corrections at RHIC (open access)

Optics measurements and corrections at RHIC

The further improvement of RHIC luminosity performance requires more precise understanding of the RHIC modeling. Hence, it is necessary to minimize the beta-beat, deviation of measured beta function from the calculated beta functions based on an model. The correction of betabeat also opens up the possibility of exploring operating RHIC polarized protons at a working point near integer, a prefered choice for both luminosity as well as beam polarization. The segment-by-segment technique for reducing beta-beat demonstrated in the LHC operation for reducing the beta-beat was first tested in RHIC during its polarized proton operation in 2011. It was then fully implemented during the RHIC polarized proton operation in 2012. This paper reports the commissioning results. Future plan is also presented.
Date: May 20, 2012
Creator: M., Bai; Aronson, J.; Blaskiewicz, M.; Luo, Y.; Robert-Demolaize, G. & White, S.
Object Type: Article
System: The UNT Digital Library
Compact, Interactive Electric Vehicle Charger (open access)

Compact, Interactive Electric Vehicle Charger

Advanced Research Projects Agency-Energy project sheet summarizing general information about the Agile Delivery of Electrical Power Technology (ADEPT) program including critical needs, innovation and advantages, impacts, and contact information. This sheet discusses a battery-to-grid energy distribution design as part of the "Gallium-Nitride Switch Technology for Bi-Directional Battery-to-Grid Charger Applications" project.
Date: May 8, 2012
Creator: HRL Laboratories, LLC
Object Type: Text
System: The UNT Digital Library
Status Update of the Power Conditioning System in the National Ignition Facility (open access)

Status Update of the Power Conditioning System in the National Ignition Facility

None
Date: May 24, 2012
Creator: Galloudec, B. L.; Arnold, P.; James, G.; Pendleton, D.; Petersen, D.; Arellano-Womack, G. et al.
Object Type: Article
System: The UNT Digital Library
Laboratory Study of Hall Reconnection in Partially Ionized Plasmas (open access)

Laboratory Study of Hall Reconnection in Partially Ionized Plasmas

The effects of partial ionization (ni/nn ≤ 1%) on magnetic reconnection in the Hall regime have been studied systematically in the Magnetic Reconnection Experiment (MRX). It is shown that, when neutrals are added the Hall quadrupole field pattern and thus electron flow is unchanged while the ion outflow speed is reduced due to ion-neutral drag. However, in constrast to theoretical predictions, the ion diffusion layer width does not change appreciably. Therefore, the total ion outflow flux and the normalized reconnection rate are reduced.
Date: May 15, 2012
Creator: Eric E. Lawrence, Hanto Ji, Masaaki Yamaada and Jongsoo Yoo
Object Type: Report
System: The UNT Digital Library
Longitudinal Emittance Growth Due to Nonlinear Space Charge Effect (open access)

Longitudinal Emittance Growth Due to Nonlinear Space Charge Effect

None
Date: May 10, 2012
Creator: Lau, Y. Y.; Yu, S. S.; Barnard, J. J. & Seidl, P. A.
Object Type: Article
System: The UNT Digital Library
Science and Technology Review, July/August 2012 (open access)

Science and Technology Review, July/August 2012

This month's issue has the following articles: (1) Energetic Materials Research Finds an Enduring Home and Mission - Commentary by Bruce T. Goodwin; (2) A Home for Energetic Materials and Their Experts - The Energetic Materials Center has become the National Nuclear Security Administration's go-to facility for high explosives formulation, testing, and expertise; (3) A Spectra-Tacular Sight - Scientists use spectrographic techniques and a high-powered telescope to study the atmospheric composition of exoplanets; (4) Seismic Data Pinpoint Fractures for Geothermal Energy - Livermore researchers are developing advanced microseismic analysis techniques to understand what happens beneath Earth's surface, where hot rock can provide an energy source; and (5) Employees Keep Up with the Times - The Laboratory's Education Assistance Program helps its workforce stay productive, skilled, and dynamic.
Date: May 30, 2012
Creator: Poyneer, L A
Object Type: Report
System: The UNT Digital Library
Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics (open access)

Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics

In order to achieve peak luminosity of a Muon Collider (MC) in the 10{sup 35} cm{sup -2}s{sup -1} range very small values of beta-function at the interaction point (IP) are necessary ({beta}* {le} 1 cm) while the distance from IP to the first quadrupole can not be made shorter than {approx}6 m as dictated by the necessity of detector protection from backgrounds. In the result the beta-function at the final focus quadrupoles can reach 100 km making beam dynamics very sensitive to all kind of errors. In the present report we consider the effects on momentum acceptance and dynamic aperture of multipole field errors in the body of IR dipoles as well as of fringe-fields in both dipoles and quadrupoles in the ase of 1.5 TeV (c.o.m.) MC. Analysis shows these effects to be strong but correctable with dedicated multipole correctors.
Date: May 1, 2012
Creator: Alexahin, Y.; Gianfelice-Wendt, E.; Kapin, V.V. & /Fermilab
Object Type: Article
System: The UNT Digital Library