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4,272 Matching Results
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Development of An On-Line, Core Power Distribution Monitoring System
The objective of the proposed work was to develop a software package that can construct in three-dimensional core power distributions using the signals from constant temperature power sensors distributed in the reactor core. The software developed uses a mode-based state/parameter estmation technique that is particularly attractive when there are model uncertainties and/or large signal noise. The software yields the expected value of local power at the detector locations and points in between, as well as the probability distribution of the local power density
Date:
October 2, 2007
Creator:
ALdemir, Tunc; Miller, Don & Wang, Peng
Object Type:
Report
System:
The UNT Digital Library
Construction and Testing of a Low-power Cryostat for MARS
A low-power cryostat was designed and built for the Multi-sensor Airborne Radiation Survey (MARS) project for the purpose of housing a close-packed high-purity germanium (HPGe) detector array of 14 HPGe detectors. The power consumption of the cold mass in the cryostat was measured to be 4.07(11) watts, sufficient for 5.5 days of continuous operation using only 8 liters of liquid nitrogen. Temperatures throughout the cryostat were measured by platinum resistance temperature detectors. These measurements were used to determine the emissivity of the copper used in the floating radiation shield and outer cryostat wall, which was constructed using chemically cleaned and passivated copper metal. Using a PNNL-developed passivation process, an emissivity of 2.5(3)% was achieved for copper.
Date:
October 1, 2007
Creator:
Aalseth, Craig E.; Caggiano, Joseph A.; Day, Anthony R.; Fast, James E. & Fuller, Erin S.
Object Type:
Report
System:
The UNT Digital Library
Search for Standard Model Higgs Bosons Produced in Association with W Bosons
The authors report on the results of a search for standard model Higgs bosons produced in association with W bosons from p{bar p} collisions at {radical}s = 1.96 TeV. The search uses a data sample corresponding to approximately 1 fb{sup -1} of integrated luminosity. Events consistent with the W {yields} {ell}{nu} and H {yields} b{bar b} signature are selected by triggering on a high-p{sub T} electron or muon candidate and tagging one or two of the jet candidates as having originated from b quarks. A neural network filter rejects a fraction of tagged charm and light flavor jets, increasing the b-jet purity in the sample and thereby reducing the background to Higgs boson production. They observe no excess {ell}{nu}b{bar b} production beyond the background expectation, and they set 95% confidence level upper limits on the production cross section times branching fraction {sigma}(p{bar p} {yields} WH) {center_dot} Br(H {yields} b{bar b}) ranging from 3.9 to 1.3 pb, for specific Higgs boson mass hypotheses in the range 110 to 150 GeV/c{sup 2}, respectively.
Date:
October 1, 2007
Creator:
Aaltonen, T.
Object Type:
Article
System:
The UNT Digital Library
High Sensitivity Neutron Assay of Grouted Spent Nuclear Fuel Sludge at Hanford
The disposal of the North Loadout Pit (NLOP) waste at Hanford will produce 208-liter grouted sludge drums bearing transuranic (TRU) radionuclides and fission products. Discrimination between low level waste (LLW) and TRU waste requires a lower limit of detection (LLD) of less than 100 nCi (3700 Bq) of TRU alpha activity per gram of waste matrix in order to correctly certify the final waste form. Hanford's Waste Receiving and Processing (WRAP) facility operates two identical Imaging Passive Active Neutron (IPAN{trademark}) systems which had previously demonstrated this low detection limit capability for debris waste. These two IPAN{trademark} systems were selected as the appropriate technology to assay this challenging waste stream.
Date:
October 12, 2007
Creator:
Abdurrahman, N. M.
Object Type:
Article
System:
The UNT Digital Library
Electric Transmission: Approaches for Energizing a Sagging Industry
This report discusses factors that have contributed to the lack of new transmission capacity and some of the resulting issues.
Date:
October 3, 2007
Creator:
Abel, Amy
Object Type:
Report
System:
The UNT Digital Library
Measurement of Transverse Single-Spin Asymmetries for Di-JetProduction in Proton-Proton Collisions at sqrt s = 200 GeV
We report the first measurement of the opening angledistribution between pairs of jets produced in high-energy collisions oftransversely polarized protons. The measurement probes (Sivers)correlations between the transverse spin orientation of a proton and thetransverse momentum directions of its partons. With both beams polarized,the wide pseudorapidity (-1 leq eta leq +2) coverage for jets permitsseparation of Sivers functions for the valence and sea regions. Theresulting asymmetries are all consistent with zero and considerablysmaller than Sivers effects observed in semi-inclusive deep inelasticscattering (SIDIS). We discuss theoretical attempts to reconcile the newresults with the sizable transverse spin effects seen in SIDIS andforward hadron production in pp collisions.
Date:
October 2, 2007
Creator:
Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type:
Article
System:
The UNT Digital Library
Thermodynamic ground states of platinum metal nitrides
We have systematically studied the thermodynamic stabilities of various phases of the nitrides of the platinum metal elements using density functional theory. We show that for the nitrides of Rh, Pd, Ir and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability can extend up to 17 GPa for PtN{sub 2}. Furthermore, we show that according to calculations using the local density approximation, these new compounds are also thermodynamically stable at ambient pressure and thus may be the ground state phases for these materials. We further discuss the fact that the local density and generalized gradient approximations predict different values of the absolute formation enthalpies as well different relative stabilities between simple tetragonal and the pyrite or marcasite structures.
Date:
October 9, 2007
Creator:
Aberg, D; Sadigh, B; Crowhurst, J & Goncharov, A
Object Type:
Article
System:
The UNT Digital Library
Propuesta metodológica para el control de calidad de datos de precipitación
Article discussing a methodological proposal for the quality control of precipitation data.
Date:
October 23, 2007
Creator:
Ablan, Magdiel; Andressen, Rigoberto; Vargas, Mary Pili & Acevedo, Miguel F.
Object Type:
Article
System:
The UNT Digital Library
Comparison between S/1 and R/1 tests and damage density vs. fluence (rho(phi)) results for unconditioned and sub-nanosecond laser-conditioned KD2PO4 crystals
We present S/1 and R/1 test results on unconditioned and 355 nm (3{omega}), 500 ps laser conditioned DKDP. We find up to {approx}2.5X improvement in fluence in the S/1 performance after 3{omega}, 500 ps conditioning to 5 J/cm{sup 2}. For the first time, we observe a shift to higher fluences in the R/1 results for DKDP at 3{omega}, 7 ns due to 500 ps laser conditioning. The S/1 results are compared to {rho}({phi}) results previously measured on the same DKDP crystal [1]. A consistent behavior in fluence was found between the S/1 and {rho}({phi}) results for unconditioned and 500 ps conditioned DKDP. We were successful at using Poisson statistics to derive a connection between the S/1 and {rho}({phi}) results that could be tested with our data sets by trying to predict the shape of the {rho}({phi}) curve. The value for the power dependence on fluence of {rho}({phi}) derived from the S/1 data was {approx}11 {+-} 50%. The results presented and discussed here imply a strong correlation between the damage probability (S/1) test and {rho}({phi}). We find a consistent description of the two test types in terms of a power law {rho}({phi}) and that this basic shape held for all cases, …
Date:
October 31, 2007
Creator:
Adams, J. J.; Jarboe, J.; Feit, M. & Hackel, R.
Object Type:
Article
System:
The UNT Digital Library
Confirmatory Survey Report for the Quehanna Decommissioning Project, Karthaus, PA
The survey activities consisted of visual inspections and radiological surveys including beta and gamma surface scans and surface beta activity measurements.
Date:
October 30, 2007
Creator:
Adams, W. C.
Object Type:
Report
System:
The UNT Digital Library
The CMS dataset bookkeeping service
The CMS Dataset Bookkeeping Service (DBS) has been developed to catalog all CMS event data from Monte Carlo and Detector sources. It provides the ability to identify MC or trigger source, track data provenance, construct datasets for analysis, and discover interesting data. CMS requires processing and analysis activities at various service levels and the DBS system provides support for localized processing or private analysis, as well as global access for CMS users at large. Catalog entries can be moved among the various service levels with a simple set of migration tools, thus forming a loose federation of databases. DBS is available to CMS users via a Python API, Command Line, and a Discovery web page interfaces. The system is built as a multi-tier web application with Java servlets running under Tomcat, with connections via JDBC to Oracle or MySQL database backends. Clients connect to the service through HTTP or HTTPS with authentication provided by GRID certificates and authorization through VOMS. DBS is an integral part of the overall CMS Data Management and Workflow Management systems.
Date:
October 1, 2007
Creator:
Afaq, Anzar,; /Fermilab; Dolgert, Andrew; /Cornell U., Phys. Dept.; Guo, Yuyi; /Fermilab et al.
Object Type:
Article
System:
The UNT Digital Library
Geometric Transitions and Dynamical SUSY Breaking
We show that the physics of D-brane theories that exhibit dynamical SUSY breaking due to stringy instanton effects is well captured by geometric transitions, which recast the non-perturbative superpotential as a classical flux superpotential. This allows for simple engineering of Fayet, Polonyi, O'Raifeartaigh, and other canonical models of supersymmetry breaking in which an exponentially small scale of breaking can be understood either as coming from stringy instantons or as arising from the classical dynamics of fluxes.
Date:
October 1, 2007
Creator:
Aganagic, Mina; Beem, Christopher; Kachru, Shamit & /UC, Berkeley /SLAC
Object Type:
Article
System:
The UNT Digital Library
Feasibility Study of Using Short Wave Infrared Cavity Ringdown Spectroscopy (SWIR-CRDS) for Biological Agent Detection
This project focused on determining the feasibility of using short wave infrared (SWIR) cavity ring down spectroscopy (CRDS) as a means for real-time detection of biological aerosols. The first part of the project involved identifying biological agent signatures that could be detected with SWIR CRDS. After an exhaustive search of the open literature it was determined that whole biological spores and/or cells would not be good candidates for direct SWIR CRDS probing because they have no unique SWIR signatures. It was postulated that while whole cells or spores are not good candidates for SWIR CRDS detection, their pyrolysis break-down products might be. A literature search was then conducted to find biological pyrolysis products with low molecular weights and high symmetry since these species most likely would have overtone and combination vibrational bands that can be detected in the SWIR. It was determined that pyrrole, pyridine and picolinamide were good candidates for evaluation. These molecules are formed when proteins and porphyrins, proteins and dipicolinic acid, and dipicolinic acid are pyrolyzed, respectively. The second part of the project involved measuring quantitative SWIR spectra of pyrrole, pyridine and picolinamide in PNNL’s FTIR Spectroscopy Laboratory. Spectral information about these molecules, in the vapor phase …
Date:
October 1, 2007
Creator:
Aker, Pam M.; Johnson, Timothy J.; Williams, Richard M. & Valentine, Nancy B.
Object Type:
Report
System:
The UNT Digital Library
LCLS LLRF Upgrades to the SLAC Linac
The Linac Coherent Light Source (LCLS) at SLAC will be the brightest X-ray laser in the world when it comes on line. In order to achieve the brightness a 200fS length electron bunch is passed through an undulator. To create the 200fS, 3kA bunch, a 10pS electron bunch, created from a photo cathode in an RF gun, is run off crest on the RF to set up a position to energy correlation. The bunch is then compressed by chicanes. The stability of the RF system is critical in setting up the position to energy correlation. Specifications derived from simulations require the RF system to be stable to below 200fS in several critical injector stations and the last kilometer of linac. The SLAC linac RF system is being upgraded to meet these requirements.
Date:
October 4, 2007
Creator:
Akre, R.; Dowell, D.; Emma, P.; Frisch, J.; Hong, B.; Kotturi, K. et al.
Object Type:
Article
System:
The UNT Digital Library
Tools for characterizing biomembranes : final LDRD report.
A suite of experimental nuclear magnetic resonance (NMR) spectroscopy tools were developed to investigate lipid structure and dynamics in model membrane systems. By utilizing both multinuclear and multidimensional NMR experiments a range of different intra- and inter-molecular contacts were probed within the membranes. Examples on pure single component lipid membranes and on the canonical raft forming mixture of DOPC/SM/Chol are presented. A unique gel phase pretransition in SM was also identified and characterized using these NMR techniques. In addition molecular dynamics into the hydrogen bonding network unique to sphingomyelin containing membranes were evaluated as a function of temperature, and are discussed.
Date:
October 1, 2007
Creator:
Alam, Todd Michael; Stevens, Mark; Holland, Gregory P. & McIntyre, Sarah K.
Object Type:
Report
System:
The UNT Digital Library
An Introduction to MODS: The Metadata Object Description Schema
This Tech Talks presentation offers an introduction to MODS. The presenter utilizes real life examples to show how MODS can be used with the Metadata Encoding and Transmission Standard (METS).
Date:
October 17, 2007
Creator:
Alemneh, Daniel Gelaw
Object Type:
Presentation
System:
The UNT Digital Library
Timpson & Tenaha News (Timpson, Tex.), Vol. 22, No. 40, Ed. 1 Thursday, October 4, 2007
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
October 4, 2007
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 25, No. 41, Ed. 1 Thursday, October 11, 2007
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
October 11, 2007
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 25, No. 42, Ed. 1 Thursday, October 18, 2007
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
October 18, 2007
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Timpson & Tenaha News (Timpson, Tex.), Vol. 25, No. 43, Ed. 1 Thursday, October 25, 2007
Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.
Date:
October 25, 2007
Creator:
Alexander, Nancy
Object Type:
Newspaper
System:
The Portal to Texas History
Osmose Experiment Representativity Studies.
The OSMOSE program aims at improving the neutronic predictions of advanced nuclear fuels through measurements in the MINERVE facility at the CEA-Cadarache (France) on samples containing the following separated actinides: Th-232, U-233, U-234, U-235, U-236, U-238, Np-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Am-241, Am-243, Cm-244 and Cm-245. The goal of the experimental measurements is to produce a database of reactivity-worth measurements in different neutron spectra for the separated heavy nuclides. This database can then be used as a benchmark for integral reactivity-worth measurements to verify and validate reactor analysis codes and integral cross-section values for the isotopes tested. In particular, the OSMOSE experimental program will produce very accurate sample reactivity-worth measurements for a series of actinides in various spectra, from very thermalized to very fast. The objective of the analytical program is to make use of the experimental data to establish deficiencies in the basic nuclear data libraries, identify their origins, and provide guidelines for nuclear data improvements in coordination with international programs. To achieve the proposed goals, seven different neutron spectra can be created in the MINERVE facility: UO2 dissolved in water (representative of over-moderated LWR systems), UO2 matrix in water (representative of LWRs), a mixed oxide fuel matrix, …
Date:
October 10, 2007
Creator:
Aliberti, G. & Klann, R.
Object Type:
Report
System:
The UNT Digital Library
Fission Spectrum Related Uncertainties
The paper presents a preliminary uncertainty analysis related to potential uncertainties on the fission spectrum data. Consistent results are shown for a reference fast reactor design configuration and for experimental thermal configurations. However the results obtained indicate the need for further analysis, in particular in terms of fission spectrum uncertainty data assessment.
Date:
October 1, 2007
Creator:
Aliberti, G.; Kodeli, I.; Palmiotti, G. & Salvatores, M.
Object Type:
Article
System:
The UNT Digital Library
Simultaneous Nuclear Data Target Accuracy Study for Innovative Fast Reactors
The present paper summarizes the major outcomes of a study conducted within a Nuclear Energy Agency Working Party on Evaluation Cooperation (NEA WPEC) initiative aiming to investigate data needs for future innovative nuclear systems, to quantify them and to propose a strategy to meet them
Date:
October 1, 2007
Creator:
Aliberti, G.; Palmiotti, G. & Salvatores, M.
Object Type:
Article
System:
The UNT Digital Library
Target Accuracy Assessment for an ADS Design
Nuclear data uncertainties and their impact on a very wide range of reactor systems, including their associated fuel cycles, have to be assessed in order to consolidate preliminary design studies for new innovative systems. One specific class of systems is the so-called “dedicated waste transmuters”, that are fast neutron systems (critical or sub-critical, i.e. ADS), loaded with a Minor Actinide (MA) dominated fuel and potentially uranium-free. The availability of very general tools for sensitivity and uncertainty analysis together with new variance-covariance matrix data, produced in a joint effort under the auspices of the OECD-NEA by the world leading nuclear data evaluation groups, makes that endeavor particularly significant. In this report major results of interest for dedicated ADS are discussed and the most important fields and data types are pointed out, where priority improvements are required.
Date:
October 1, 2007
Creator:
Aliberti, G.; Palmiotti, G. & Salvatores, M.
Object Type:
Article
System:
The UNT Digital Library