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363 Matching Results

Start Over Access Open Access Year 2011 Day 16th Language English

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Results: 1 - 24 of 363 next

(open access)

Noise Performance Evaluation of the Candidate Digitizers for the MAJORANA DEMONSTRATOR

The noise performance evaluation of the two digitizer cards being considered for the MAJORANA DEMONSTRATOR (MJD) is presented in this document. The procurement of the data acquisition electronics for the MJD is scheduled to happen this year. At the time of writing this document, there are two candidate digitizer electronic boards. One aspect that is being considered by the collaboration is the feasibility of using the MJD for dark matter searches. The feasibility of using the MJD for this application is going to be dictated by the ability of the demonstrator to reach sub-keV energy resolution. One of the potential sources of noise in the MJD is the data acquisition system. This document will is concluded with a recommendation for the final digitizer board by comparing the noise performance of the two electronics systems. Noise parameters such as the effective number of bits, input range linearity and signal to noise ratio are experimentally determined. The two digitizer cards feature different on-board digital signal processing and these features are compared. The experimental set-up was also used to identify sources of noise. This paper describes these sources of noise in the data acquisition system, along with mitigation strategies. Issues such as grounding …

Date: March 16, 2011

Creator: Aguayo Navarrete, Estanislao

Object Type: Report

System: The UNT Digital Library

(open access)

Availability Performance and Considerations for LCLS X-Ray FEL at SLAC

The Linac Coherent Light Source (LCLS) is an X-ray Free Electron Laser (FEL) facility located at the SLAC National Accelerator Laboratory. LCLS has been in operation since spring 2009, and it has completed its 3rd user run. LCLS is the first in its class of X-ray FEL user facilities, and presents different availability challenges compared to storage ring light sources. This paper presents recent availability performance of the FEL as well as factors to consider when defining the operational availability figure of merit for user runs. During LCLS [1] user runs, an availability of 95% has been set as a goal. In run III, LCLS photon and electron beam systems achieved availabilities of 94.8% and 96.7%, respectively. The total availability goal can be distributed among subsystems to track performance and identify areas that need attention in order to maintain and improve hardware reliability and operational availability. Careful beam time accounting is needed to understand the distribution of down time. The LCLS complex includes multiple experimental hutches for X-ray science, and each user program has different requirements of a set of parameters that the FEL can be configured to deliver. Since each user may have different criteria for what is considered …

Date: August 16, 2011

Creator: Allen, W. B.; Brachmann, A.; Colocho, W.; Stanek, M. & Warren, J.

Object Type: Article

System: The UNT Digital Library

(open access)

Political Transition in Tunisia

This report discusses Tunisia's "Jasmine Revolution," the common term for President Zine El Abidine Ben Ali's flight from the country following weeks of mounting anti-government protests. This report discusses how the Jasmine Revolution appears to have added momentum to anti-government sentiment in Egypt, Libya, Yemen, and other countries. This report discusses Tunisia's pro-democracy movement; concerns over potential instability in a previously secure, pro-Western area; and U.S.-Tunisian relations.

Date: December 16, 2011

Creator: Arieff, Alexis

Object Type: Report

System: The UNT Digital Library

(open access)

The Debt Limit: History and Recent Increases

This report discusses how the total debt of the federal government can increase, an historical overview of debt limits, and how the current economic slowdown has led to higher deficits and thereby a series of debt limit increases, as well as legislation related to these increases.

Date: May 16, 2011

Creator: Austin, D. Andrew & Levit, Mindy R.

Object Type: Report

System: The UNT Digital Library

(open access)

The Rambler (Fort Worth, Tex.), Vol. 94, No. 5, Ed. 1 Wednesday, February 16, 2011

Weekly student newspaper from Texas Wesleyan University in Fort Worth, Texas that includes campus and local news along with advertising.

Date: February 16, 2011

Creator: Banks, Shauna

Object Type: Newspaper

System: The Portal to Texas History

(open access)

Quartz Crystal Microbalance Data

We are using a Qpod quartz crystal microbalance (manufactured by Inficon) for use as a low-volume non-volatile residue analysis tool. Inficon has agreed to help troubleshoot some of our measurements and are requesting to view some sample data, which are attached. The basic principle of an NVR analysis is to evaporate a known volume of solvent, and weigh the remaining residue to determine the purity of the solvent. A typical NVR analysis uses 60 g of solvent and can measure residue with an accuracy of +/- 0.01 mg. The detection limit is thus (0.01 mg)/(60 g) = 0.17 ppm. We are attempting to use a quartz crystal microbalance (QCM) to make a similar measurement. The attached data show the response of the QCM as a 5-20 mg drop of solvent evaporates on its surface. The change in mass registered by the QCM after the drop evaporates is the residue that deposits on the crystal. On some measurements, the change in mass in less than zero, which is aphysical since the drop will leave behind {>=}0 mass of residue. The vendor, Inficon, has agreed to look at these data as a means to help troubleshoot the cause.

Date: November 16, 2011

Creator: Baxamusa, S H

Object Type: Report

System: The UNT Digital Library

(open access)

Energy and Water Development: FY2011 Appropriations

This report discusses the Energy and Water Development appropriations bill that provides funding for civil works projects of the Army Corps of Engineers (Corps), the Department of the Interior's Bureau of Reclamation, the Department of Energy (DOE), and a number of Independent agencies.

Date: February 16, 2011

Creator: Behrens, Carl E.

Object Type: Report

System: The UNT Digital Library

(open access)

Energy and Water Development: FY2012 Appropriations

This report discusses the energy and water development appropriations bill that provides funding for civil works projects of the Army Corps of Engineers (Corps), the Department of the Interior's Bureau of Reclamation, the Department of Energy (DOE), and a number of independent agencies.

Date: August 16, 2011

Creator: Behrens, Carl E.

Object Type: Report

System: The UNT Digital Library

(open access)

Superconducting RF for energy recovery linacs of eRHIC

N/A

Date: October 16, 2011

Creator: Belomestnykh, S.; Ben-Zvi, Ilan; Hahn, H.; Mahler, G.; Than, R. & Xu, W.

Object Type: Article

System: The UNT Digital Library

(open access)

Director of National Intelligence Statutory Authorities: Status and Proposals

This report discusses the Director of National Intelligence (DNI) position created by the Intelligence Reform and Terrorism Prevention Act of 2004 (P.L. 108-458). It includes an overview of the authorities granted to the DNI by legislation in 2004 and later as well as the varying opinions of Congress regarding new DNI authorities, as well as related legislation from FY2010 through FY2012.

Date: December 16, 2011

Creator: Best, Richard A., Jr.

Object Type: Report

System: The UNT Digital Library

(open access)

Federal Market Information Technology in the Post Flash Crash Era: Roles for Supercomputing

This paper describes collaborative work between active traders, regulators, economists, and supercomputing researchers to replicate and extend investigations of the Flash Crash and other market anomalies in a National Laboratory HPC environment. Our work suggests that supercomputing tools and methods will be valuable to market regulators in achieving the goal of market safety, stability, and security. Research results using high frequency data and analytics are described, and directions for future development are discussed. Currently the key mechanism for preventing catastrophic market action are “circuit breakers.” We believe a more graduated approach, similar to the “yellow light” approach in motorsports to slow down traffic, might be a better way to achieve the same goal. To enable this objective, we study a number of indicators that could foresee hazards in market conditions and explore options to confirm such predictions. Our tests confirm that Volume Synchronized Probability of Informed Trading (VPIN) and a version of volume Herfindahl-Hirschman Index (HHI) for measuring market fragmentation can indeed give strong signals ahead of the Flash Crash event on May 6 2010. This is a preliminary step toward a full-fledged early-warning system for unusual market conditions.

Date: September 16, 2011

Creator: Bethel, E. Wes; Leinweber, David; Ruebel, Oliver & Wu, Kesheng

Object Type: Article

System: The UNT Digital Library

(open access)

Fund for "Gifts to the United States for Reduction of the Public Debt": Current Law and Proposed Legislation

This report describes current law for the Public Debt Reduction Fund and discusses proposed legislation in order to evaluate four bills which have been introduced in the 112th Congress to add another method of making a contribution to reduce the national debt.

Date: November 16, 2011

Creator: Bickley, James M.

Object Type: Report

System: The UNT Digital Library

(open access)

Qatar: Background and U.S. Relations

This report presents an overview of Qatar's history and recent economic and political developments. The report discusses U.S. relations with Qatar, U.S. military cooperation and foreign assistance, political reform and elections, as well as human rights and social issues.

Date: May 16, 2011

Creator: Blanchard, Christopher M.

Object Type: Report

System: The UNT Digital Library

(open access)

Development of a fast cyclotron gas stopper for intense rare isotope beams from projectile fragmentation: Study of ion extraction with a radiofrequency carpet

Research and development has been performed in support of the design of a future rare isotope beam facility in the US. An important aspect of plans for earlier RIA (Rare Isotope Accelerator) and a requirement of FRIB (Facility of Rare Isotope Beams) to be built at Michigan State University are the availability of so-called “stopped beams” for research that contributes to answering questions like how elements in the universe are created and to provide better insight into the nature of Fundamental Interactions. In order to create “stopped beams” techniques are required that transform fast rare isotopes beams as they are available directly after addresses questions like the origin of that will allow and High priority is given to the evaluation of intensity limitations and the efficiency of stopping of fast fragment beams in gas cells and to the exploration of options to increase the efficiency and the reduction of space charge effects. Systematic studies performed at MSU as part of the RIA R&D with a linear gas cell under conditions close to those expected at RIA and related simulations confirm that the efficiency of stopping and extracting ions decreases with increasing beam intensity. Similar results have also been observed at …

Date: January 16, 2011

Creator: Bollen, Georg & Morrissey, David

Object Type: Report

System: The UNT Digital Library

(open access)

The Coherent X-ray Imaging (CXI) Instrument at the Linac Coherent Light Source (LCLS)

The Linac Coherent Light Source (LCLS) has become the first ever operational hard X-ray Free Electron Laser in 2009. It will operate as a user facility capable of delivering unique research opportunities in multiple fields of science. The LCLS and the LCLS Ultrafast Science Instruments (LUSI) construction projects are developing instruments designed to make full use of the capabilities afforded by the LCLS beam. One such instrument is being designed to utilize the LCLS coherent beam to image with high resolution any sub-micron object. This instrument is called the Coherent X-ray Imaging (CXI) instrument. This instrument will provide a flexible optical system capable of tailoring key beam parameters for the users. A suite of shot-to-shot diagnostics will also be provided to characterize the beam on every pulse. The provided instrumentation will include multi-purpose sample environments, sample delivery and a custom detector capable of collecting 2D data at 120 Hz. In this article, the LCLS will be briefly introduced along with the technique of Coherent X-ray Diffractive Imaging (CXDI). A few examples of scientific opportunities using the CXI instrument will be described. Finally, the conceptual layout of the instrument will be presented along with a description of the key requirements for …

Date: August 16, 2011

Creator: Boutet, Sebastien & Williams, Garth J.

Object Type: Article

System: The UNT Digital Library

(open access)

Final Technical Report

The Consortium of Big-10 University Research and Training Reactors was by design a strategic partnership of seven leading institutions. We received the support of both our industry and DOE laboratory partners. Investiments in reactor, laboratory and program infrastructure, allowed us to lead the national effort to expand and improve the education of engineers in nuclear science and engineering, to provide outreach and education to pre-college educators and students and to become a key resource of ideas and trained personnel for our U.S. industrial and DOE laboratory collaborators.

Date: May 16, 2011

Creator: Brenizer, Jack

Object Type: Report

System: The UNT Digital Library