New Constraints on Isospin-Violating Dark Matter (open access)

New Constraints on Isospin-Violating Dark Matter

None
Date: March 20, 2013
Creator: Kumar, Jason; U., /Hawaii; Sanford, David; /UC, Irvine; Strigari, Louis E. & /KIPAC, Menlo Park /Stanford U., Phys. Dept.
Object Type: Article
System: The UNT Digital Library
Tools for Predicting Optical Damage on Inertial Confinement Fusion-Class Laser Systems (open access)

Tools for Predicting Optical Damage on Inertial Confinement Fusion-Class Laser Systems

Operating a fusion-class laser to its full potential requires a balance of operating constraints. On the one hand, the total laser energy delivered must be high enough to give an acceptable probability for ignition success. On the other hand, the laser-induced optical damage levels must be low enough to be acceptably handled with the available infrastructure and budget for optics recycle. Our research goal was to develop the models, database structures, and algorithmic tools (which we collectively refer to as ''Loop Tools'') needed to successfully maintain this balance. Predictive models are needed to plan for and manage the impact of shot campaigns from proposal, to shot, and beyond, covering a time span of years. The cost of a proposed shot campaign must be determined from these models, and governance boards must decide, based on predictions, whether to incorporate a given campaign into the facility shot plan based upon available resources. Predictive models are often built on damage ''rules'' derived from small beam damage tests on small optics. These off-line studies vary the energy, pulse-shape and wavelength in order to understand how these variables influence the initiation of damage sites and how initiated damage sites can grow upon further exposure to …
Date: December 20, 2010
Creator: Nostrand, M. C.; Carr, C. W.; Liao, Z. M.; Honig, J.; Spaeth, M. L.; Manes, K. R. et al.
Object Type: Report
System: The UNT Digital Library
Hadronic Decays Related to Gamma at BaBar (open access)

Hadronic Decays Related to Gamma at BaBar

None
Date: June 20, 2013
Creator: Lopez-March, Neus & /Valencia U., IFIC
Object Type: Article
System: The UNT Digital Library
Shielding of a hadron in a finite e-beam (open access)

Shielding of a hadron in a finite e-beam

The thorough study of coherent electron cooling, the modern cooling technique capable to deal with accelerators operating in the range of few TeVs, rises many interesting questions. One of them is a shielding dynamics of a hadron in an electron beam. Now this effect is computed analytically in the infinite beam approximation. Many effects are drastically different in finite and infinite plasmas. Here we propose a method to compute the dynamical shielding effect in a finite cylindrical plasma - the realistic model of an electron beam in accelerators.
Date: May 20, 2012
Creator: A., Elizarov; Litvinenko, V. & Wang, G.
Object Type: Article
System: The UNT Digital Library
Chromium isotopes as indicators of hexavalent chromium reduction (open access)

Chromium isotopes as indicators of hexavalent chromium reduction

This is the final report for a university research project which advanced development of a new technology for identifying chemical reduction of hexavalent chromium contamination in groundwater systems. Reduction renders mobile and toxic hexavalent chromium immobile and less toxic. The new method uses stable isotope ratio measurements, which are made using multicollector ICP-mass spectrometry. The main objectives of this project were completed during the project period and two peer-reviewed articles were published to disseminate the information gained.
Date: March 20, 2012
Creator: Johnson, Thomas M.
Object Type: Report
System: The UNT Digital Library
High Speed, Low Cost Fabrication of Gas Diffusion Electrodes for Membrane Electrode Assemblies (open access)

High Speed, Low Cost Fabrication of Gas Diffusion Electrodes for Membrane Electrode Assemblies

Fabrication of membrane electrode assemblies (MEAs) depends on creating inks or pastes of catalyst and binder, and applying this suspension to either the membrane (catalyst coated membrane) or gas diffusion media (gas diffusion electrode) and respectively laminating either gas diffusion media or gas diffusion electrodes (GDEs) to the membrane. One barrier to cost effective fabrication for either of these approaches is the development of stable and consistent suspensions. This program investigated the fundamental forces that destabilize the suspensions and developed innovative approaches to create new, highly stable formulations. These more concentrated formulations needed fewer application passes, could be coated over longer and wider substrates, and resulted in significantly lower coating defects. In March of 2012 BASF Fuel Cell released a new high temperature product based on these advances, whereby our customers received higher performing, more uniform MEAs resulting in higher stack build yields. Furthermore, these new materials resulted in an “instant” increase in capacity due to higher product yields and material throughput. Although not part of the original scope of this program, these new formulations have also led us to materials that demonstrate equivalent performance with 30% less precious metal in the anode. This program has achieved two key milestones …
Date: September 20, 2013
Creator: DeCastro, Emory S.; Tsou, Yu-Min & Liu, Zhenyu
Object Type: Report
System: The UNT Digital Library
Comment on "Wall Forces Produced During ITER Disruptions" by H. R. Strauss, R. Paccagnella, and J. Breslau (PHYSICS OF PLASMAS 17, 082505 (2010) (open access)

Comment on "Wall Forces Produced During ITER Disruptions" by H. R. Strauss, R. Paccagnella, and J. Breslau (PHYSICS OF PLASMAS 17, 082505 (2010)

The paper by H.R. Strauss presents numerical simulations, which pretend to describe the disruption instability in ITER device. The simulations were performed with numerical code M3D, described in Ref.[7] of the paper.
Date: October 20, 2010
Creator: Zakharov, Leonid E.
Object Type: Report
System: The UNT Digital Library
ARM CLASIC ER2 CRS/EDOP (open access)

ARM CLASIC ER2 CRS/EDOP

Data was taken with the NASA ER-2 aircraft with the Cloud Radar System and other instruments in conjunction with the DOE ARM CLASIC field campaign. The flights were near the SGP site in north Central Oklahoma and targeted small developing convection. The CRS is a 94 GHz nadir pointing Doppler radar. Also on board the ER-2 was the Cloud Physics Lidar (CPL). Seven science flights were conducted but the weather conditions did not cooperate in that there was neither developing convection, or there was heavy rain.
Date: December 20, 2010
Creator: Heymsfield, Gerald
Object Type: Text
System: The UNT Digital Library
Review of the Recent Frequency Performance of the Eastern, Western and ERCOT Interconnections (open access)

Review of the Recent Frequency Performance of the Eastern, Western and ERCOT Interconnections

The reliable operation of an electric power system depends on careful management of the balance between generation and load to ensure that system frequency is maintained within narrow bounds around a scheduled value. Yet, maintaining frequency at the scheduled value is challenging because the load served is continuously changing, and occasionally, events such as the sudden loss of a large generation plant or large amount of load, cause frequency to deviate abruptly. This report reviews the recent history of frequency performance for all three U.S. interconnections: Eastern, Western, and the Electric Reliability Council of Texas (ERCOT). The review is based on data collected by the North American Electric Reliability Corporation (NERC). The review focuses on frequency response, which measures the performance of the interconnections immediately following sudden, large imbalances between load and generation. Trends in frequency response are presented and preliminary efforts are made to relate frequency response to other aspects of frequency performance and to examine aspects of the methods used to calculate frequency response.
Date: December 20, 2010
Creator: Lacommare, Kristina S H
Object Type: Report
System: The UNT Digital Library
OFFICE OF TECHNOLOGY INNOVATION AND DEVELOPMENT TECHNOLOGY DEVELOPMENT REPORT FY2011 (open access)

OFFICE OF TECHNOLOGY INNOVATION AND DEVELOPMENT TECHNOLOGY DEVELOPMENT REPORT FY2011

None
Date: October 20, 2011
Creator: Bush, S. & Douglas, B.
Object Type: Report
System: The UNT Digital Library
Survey of nucleon electromagnetic form factors (open access)

Survey of nucleon electromagnetic form factors

There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has been greatly improved by performing double polarization experiments, in compar- ison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at MIT-Bates, MAMI, and JLab. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed.
Date: September 20, 2011
Creator: Perdrisat, Charles F. & Punjabi, Vina A.
Object Type: Article
System: The UNT Digital Library
Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX-II) (open access)

Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX-II)

To heat targets to electron-volt temperatures for the study of warm dense matter with intense ion beams, low mass ions, such as lithium, have an energy loss peak (dE/dx) at a suitable kinetic energy. The Heavy Ion Fusion Sciences (HIFS) program at Lawrence Berkeley National Laboratory will carry out warm dense matter experiments using Li{sup +} ion beam with energy 1.2-4 MeV in order to achieve uniform heating up to 0.1-1 eV. The accelerator physics design of Neutralized Drift Compression Experiment (NDCX-II) has a pulse length at the ion source of about 0.5 {micro}s. Thus for producing 50 nC of beam charge, the required beam current is about 100 mA. Focusability requires a normalized (edge) emittance {approx}2 {pi}-mm-mrad. Here, lithium aluminosilicate ion sources, of {beta}-eucryptite, are being studied within the scope of NDCX-II construction. Several small (0.64 cm diameter) lithium aluminosilicate ion sources, on 70%-80% porous tungsten substrate, were operated in a pulsed mode. The distance between the source surface and the mid-plane of the extraction electrode (1 cm diameter aperture) was 1.48 cm. The source surface temperature was at 1220 C to 1300 C. A 5-6 {micro}s long beam pulsed was recorded by a Faraday cup (+300 V on …
Date: April 20, 2011
Creator: LBNL; Roy, P. K.; Greenway, W.; Kwan, J. W.; Seidl, P. A. & Waldron, W.
Object Type: Article
System: The UNT Digital Library
Effects of grids in drift tubes (open access)

Effects of grids in drift tubes

In 2011, we upgraded a 201 MHz buncher in the proton injector for the alternating gradient synchrotron (AGS) - relativistic heavy ion collider (RHIC) complex. In the buncher we installed four grids made of tungsten to improve the transit time factor. The grid installed drift tubes have 32 mm of inner diameter and the each grid consists of four quadrants. The quadrants were cut out precisely from 1mm thick tungsten plates by a computerized numerically controlled (CNC) wire cutting electrical discharge machining (EDM). The 3D electric field of the grid was simulated.
Date: May 20, 2012
Creator: M., Okamura & Yamauchi, H.
Object Type: Article
System: The UNT Digital Library
3D Equilibrium Effects Due to RMP Application on DIII-D (open access)

3D Equilibrium Effects Due to RMP Application on DIII-D

The mitigation and suppression of edge localized modes (ELMs) through application of resonant magnetic perturbations (RMPs) in Tokamak plasmas is a well documented phenomenon [1]. Vacuum calculations suggest the formation of edge islands and stochastic regions when RMPs are applied to the axisymmetric equilibria. Self-consistent calculations of the plasma equilibrium with the VMEC [2] and SPEC [3] codes have been performed for an up-down symmetric shot (142603) in DIII-D. In these codes, a self-consistent calculation of the plasma response due to the RMP coils is calculated. The VMEC code globally enforces the constraints of ideal MHD; consequently, a continuously nested family of flux surfaces is enforced throughout the plasma domain. This approach necessarily precludes the observation of islands or field-line chaos. The SPEC code relaxes the constraints of ideal MHD locally, and allows for islands and field line chaos at or near the rational surfaces. Equilibria with finite pressure gradients are approximated by a set of discrete "ideal-interfaces" at the most irrational flux surfaces and where the strongest pressure gradients are observed. Both the VMEC and SPEC calculations are initialized from EFIT reconstructions of the plasma that are consistent with the experimental pressure and current profiles. A 3D reconstruction using …
Date: June 20, 2012
Creator: Lazerson, S.; Lazarus, E.; Hudson, S.; Pablant, N. & Gates, D.
Object Type: Article
System: The UNT Digital Library
Use of Frequency Response Metrics to Assess the Planning and Operating Requirements for Reliable Integration of Variable Renewable Generation (open access)

Use of Frequency Response Metrics to Assess the Planning and Operating Requirements for Reliable Integration of Variable Renewable Generation

An interconnected electric power system is a complex system that must be operated within a safe frequency range in order to reliably maintain the instantaneous balance between generation and load. This is accomplished by ensuring that adequate resources are available to respond to expected and unexpected imbalances and restoring frequency to its scheduled value in order to ensure uninterrupted electric service to customers. Electrical systems must be flexible enough to reliably operate under a variety of"change" scenarios. System planners and operators must understand how other parts of the system change in response to the initial change, and need tools to manage such changes to ensure reliable operation within the scheduled frequency range. This report presents a systematic approach to identifying metrics that are useful for operating and planning a reliable system with increased amounts of variable renewable generation which builds on existing industry practices for frequency control after unexpected loss of a large amount of generation. The report introduces a set of metrics or tools for measuring the adequacy of frequency response within an interconnection. Based on the concept of the frequency nadir, these metrics take advantage of new information gathering and processing capabilities that system operators are developing for …
Date: December 20, 2010
Creator: Eto, Joseph H.; Undrill, John; Mackin, Peter; Daschmans, Ron; Williams, Ben; Haney, Brian et al.
Object Type: Report
System: The UNT Digital Library
Dielectric Wakefield Accelerator to drive the future FEL Light Source. (open access)

Dielectric Wakefield Accelerator to drive the future FEL Light Source.

X-ray free-electron lasers (FELs) are expensive instruments and a large part of the cost of the entire facility is driven by the accelerator. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may provide a significant cost saving and reduction of the facility size. In this article, we investigate using a collinear dielectric wakefield accelerator to provide a high repetition rate, high current, high energy beam to drive a future FEL x-ray light source. As an initial case study, a {approx}100 MV/m loaded gradient, 850 GHz quartz dielectric based 2-stage, wakefield accelerator is proposed to generate a main electron beam of 8 GeV, 50 pC/bunch, {approx}1.2 kA of peak current, 10 x 10 kHz (10 beamlines) in just 100 meters with the fill factor and beam loading considered. This scheme provides 10 parallel main beams with one 100 kHz drive beam. A drive-to-main beam efficiency {approx}38.5% can be achieved with an advanced transformer ratio enhancement technique. rf power dissipation in the structure is only 5 W/cm{sup 2} in the high repetition rate, high gradient operation mode, which is in the range of advanced water cooling capability. Details of study presented in the article include the overall …
Date: April 20, 2011
Creator: Jing, C.; Power, J. & Zholents, A.
Object Type: Report
System: The UNT Digital Library
Advanced Combustion Diagnostics and Control for Furnaces, Fired Heaters and Boilers (open access)

Advanced Combustion Diagnostics and Control for Furnaces, Fired Heaters and Boilers

The objective of this project was to develop and apply enabling tools and methods towards advanced combustion diagnostics and control of fired-equipment in large-scale petrochemical manufacturing. There are a number of technology gaps and opportunities for combustion optimization, including technologies involving advanced in-situ measurements, modeling, and thermal imaging. These technologies intersect most of manufacturing and energy systems within the chemical industry. This project leveraged the success of a previous DOE funded project led by Dow, where we co-developed an in-situ tunable diode laser (TDL) analyzer platform (with Analytical Specialties Inc, now owned by Yokogawa Electric Corp.). The TDL platform has been tested and proven in a number of combustion processes within Dow and outside of Dow. The primary focus of this project was on combustion diagnostics and control applied towards furnaces, fired heaters and boilers. Special emphasis was placed on the development and application of in-situ measurements for O2, CO and methane since these combustion gases are key variables in optimizing and controlling combustion processes safely. Current best practice in the industry relies on measurements that suffer from serious performance gaps such as limited sampling volume (point measurements), poor precision and accuracy, and poor reliability. Phase I of the project …
Date: March 20, 2010
Creator: Tate, J. D.; Le, Linh D.; Knittel,Trevor & Cowie, Alan
Object Type: Report
System: The UNT Digital Library
Ground Motion Studies at NuMI (open access)

Ground Motion Studies at NuMI

Ground motion can cause significant deterioration in the luminosity of a linear collider. Vibration of numerous focusing magnets causes continuous misalignments, which makes the beam emittance grow. For this reason, understanding the seismic vibration of all potential LC sites is essential and related efforts in many sites are ongoing. In this document we summarize the results from the studies specific to Fermilab grounds as requested by the LC project leader at FNAL, Shekhar Mishra in FY04-FY06. The Northwestern group focused on how the ground motion effects vary with depth. Knowledge of depth dependence of the seismic activity is needed in order to decide how deep the LC tunnel should be at sites like Fermilab. The measurements were made in the NuMI tunnel, see Figure 1. We take advantage of the fact that from the beginning to the end of the tunnel there is a height difference of about 350 ft and that there are about five different types of dolomite layers. The support received allowed to pay for three months of salary of Michal Szleper. During this period he worked a 100% of his time in this project. That include one week of preparation: 2.5 months of data taking and …
Date: February 20, 2012
Creator: Velasco, Mayda M. & Szleper, Michal
Object Type: Report
System: The UNT Digital Library
Office of the Chief Financial Officer Annual Report 2010 (open access)

Office of the Chief Financial Officer Annual Report 2010

In March, a review team consisting of CFOs from other national laboratories, industry, and members of the University of California Office of the President (UCOP) convened for three days to conduct a comprehensive peer review of the OCFO. This was the first time in almost a decade that the financial operations of the Laboratory had been reviewed. The Committee relayed their observations on our strengths, and their very thoughtful recommendations for improvement, which we are actively pursuing. These improvements, when implemented, will benefit the entire Laboratory for many years to come. The complete report is available on the OCFO website (www.lbl.gov/Workplace/CFO). In August, the senior management team of the OCFO participated in a strategic planning retreat. The purpose of the two and a half day exercise was, of course, to update our strategic plan, but instead of spending days developing a written document, we enlisted the expertise of a seasoned journalist who also happens to be a very talented graphic artist. He listened carefully to our ideas and committed them to a visual roadmap. All members of the OCFO, Business Managers, and the Laboratory Leadership Team reviewed this draft roadmap. By having a completely visual strategic plan that is posted …
Date: December 20, 2010
Creator: Fernandez, Jeffrey
Object Type: Report
System: The UNT Digital Library
National Transport Code Collaboration (NTCC) PTRANSP, Final Report to the US Department of Energy for the Period August 1, 2007 Through July 31, 2010 (open access)

National Transport Code Collaboration (NTCC) PTRANSP, Final Report to the US Department of Energy for the Period August 1, 2007 Through July 31, 2010

This report describes the work done under U.S. Department of Energy grant number DE-FG02-07ER54935 for the period ending July 31, 2010. The goal of this project was to provide predictive transport analysis to the PTRANSP code. Our contribution to this effort consisted of three parts: (a) a predictive solver suitable for use with highly non-linear transport models and installation of the turbulent confinement models GLF23 and TGLF, (b) an interface of this solver with the PTRANSP code, and (c) initial development of an EPED1 edge pedestal model interface with PTRANSP. PTRANSP has been installed locally on this cluster by importing a complete PTRANSP build environment that always contains the proper version of the libraries and other object files that PTRANSP requires. The GCNMP package and its interface code have been added to the SVN repository at PPPL.
Date: August 20, 2010
Creator: Lao, Lang L.; St John, Holger; Staebler, Gary M. & Snyder, Phil B.
Object Type: Report
System: The UNT Digital Library
Dual and Triple Ion-Beam Irradiations of Fe, Fe(Cr) and Fe(Cr)-ODS Final Report: IAEA SMoRE CRP (open access)

Dual and Triple Ion-Beam Irradiations of Fe, Fe(Cr) and Fe(Cr)-ODS Final Report: IAEA SMoRE CRP

Structures of nanoparticles in Fe-16Cr-4.5Al-0.3Ti-2W-0.37Y2O3 (K3) and Fe-20Cr-4.5Al-0.34Ti-0.5Y2O3 (MA956) oxide dispersion strengthened (ODS) ferritic steels produced by mechanical alloying (MA) and followed by hot extrusion have been studied using high-resolution transmission electron microscopy (HRTEM) techniques to gain insight about the formation mechanism of nanoparticles in MA/ODS steels. The observations of Y-Al-O complex-oxide nanoparticles in both ODS steels imply that decomposition of Y2O3 in association with internal oxidation of Al occurred during mechanical alloying. While the majority of oxide nanoparticles formed in both steels is Y4Al2O9, a few oxide particles of YAlO3 are also occasionally observed. These results reveal that Ti (0.3 wt %) plays an insignificant role in forming oxide nanoparticles in the presence of Al (4.5 wt %). HRTEM observations of crystalline nanoparticles larger than {approx}2 nm and amorphous or disordered cluster domains smaller than {approx}2 nm provide an insight into the formation mechanism of oxide nanoparticle in MA/ODS steels, which we believe from our observations involves a solid-state amorphous precursor followed by recrystallization. Dual ion-beam irradiations using He{sup +} + Fe{sup +8} ions were employed to gain more detailed insight about the role of nanoparticles in suppressing radiation-induced swelling. This is elaborated through TEM examinations of cavity distributions …
Date: November 20, 2011
Creator: Fluss, M. J.; Hsiung, L. L. & Marian, J.
Object Type: Report
System: The UNT Digital Library
TOXNET and Beyond: Using the National Library of Medicine's Environmental Health and Toxicology Portal (open access)

TOXNET and Beyond: Using the National Library of Medicine's Environmental Health and Toxicology Portal

The National Library of Medicine's Environmental Health and Toxicology Portal provides access to numerous databases that can help you explore environmental chemicals and risks. TOXNET and Beyond: Using NLM's Environmental Health and Toxicology Portal conveys the fundamentals of searching the NLM's TOXNET system of databases in chemistry, toxicology, environmental health, and related fields. In addition to TOXNET, the course will highlight various resources available through the Environmental Health and Toxicology Portal.
Date: October 20, 2010
Creator: Templin-Branner, W.
Object Type: Book
System: The UNT Digital Library
Measurement of the Tracer Gradient and Sampling System Bias of the Hot Fuel Examination Facility Stack Air Monitoring System (open access)

Measurement of the Tracer Gradient and Sampling System Bias of the Hot Fuel Examination Facility Stack Air Monitoring System

This report describes tracer gas uniformity and bias measurements made in the exhaust air discharge of the Hot Fuel Examination Facility at Idaho National Laboratory. The measurements were a follow-up on earlier measurements which indicated a lack of mixing of the two ventilation streams being discharged via a common stack. The lack of mixing is detrimental to the accuracy of air emission measurements. The lack of mixing was confirmed in these new measurements. The air sampling probe was found to be out of alignment and that was corrected. The suspected sampling bias in the air sample stream was disproved.
Date: July 20, 2011
Creator: Glissmeyer, John A. & Flaherty, Julia E.
Object Type: Report
System: The UNT Digital Library
NDCX-II, an Induction Linac for HEDP and IFE Research (open access)

NDCX-II, an Induction Linac for HEDP and IFE Research

The Heavy Ion Fusion Science Virtual National Laboratory in the USA is constructing a new Neutralized Drift Compression eXperiment (NDCX-II) at LBNL. This facility is being developed for high energy density physics and inertial fusion energy research. The 12 m long induction linac in NDCX-II will produce a Li{sup +} beam pulse, at energies of 1.2-3 MeV, to heat target material to the warm dense matter regime ({approx} 1 eV). By making use of special acceleration voltage waveforms, 2.5T solenoid focusing, and neutralized drift compression, 20 - 50 nC of beam charge from the ion source will be compressed longitudinally and radially to achieve a subnanosecond pulse length and mm-scale target spot size. The original Neutralized Drift Compression Experiment (NDCX-I) has successfully demonstrated simultaneous radial and longitudinal compression by imparting a velocity ramp to the ion beam, which then drifts in a neutralizing plasma to and through the final focussing solenoid and onto the target. At higher kinetic energy and current, NDCX-II will offer more than 100 times the peak energy fluence on target of NDCX-I. NDCX-II makes use of many parts from the decommissioned Advanced Test Accelerator (ATA) at LLNL. It includes 27 lattice periods between the injector and …
Date: April 20, 2011
Creator: Kwan, J. W.; Arbelaez, D.; Bieniosek, F. M.; Faltens, A.; Friedman, A.; Galvin, J. et al.
Object Type: Article
System: The UNT Digital Library