The excess flux in the cosmic submillimeter background radiation and the primordial deuterium abundance (open access)

The excess flux in the cosmic submillimeter background radiation and the primordial deuterium abundance

Recent measurements of the cosmic background radiation (CBR) show an enhanced flux in the submillimeter regime, compared to the spectrum of a 2.7 K blackbody. Thermal Comptonization of the relic radiation by a hot nonrelativistic plasma has long been known to produce distortions in the CBR spectrum, similar to what has now been observed. Heating of the primeval plasma to temperatures T {approximately} 10{sup 6} {minus} 10{sup 8} K could result from the injection of subcosmic ray protons at epoch z {approximately} 10--100. The intensity of the subcosmic ray flux that provide conditions needed to explain the submillimeter excess by thermal Comptonization also leads to the production of cosmologically significant amounts of deuterium in collisions between subcosmic ray protons and primordial protons and {alpha}-particles. However, the amount of lithium produced through {alpha}-{alpha} reactions is in conflict with the observed Li abundance. If lithium is depleted, for example, by processing through Population II stars, arguments for the baryon content of the universe based on primordial deuterium and He abundances are weakened. 12 refs., 1 fig., 1 tab.
Date: October 27, 1989
Creator: Dermer, C. D.; Guessoum, N. (Lawrence Livermore National Lab., CA (USA) & National Aeronautics and Space Administration, Greenbelt, MD (USA). Lab. for High Energy Astrophysics)
Object Type: Article
System: The UNT Digital Library
Enhanced durability and reactivity for zinc ferrite desulfurization sorbent (open access)

Enhanced durability and reactivity for zinc ferrite desulfurization sorbent

AMAX Research Development Center (AMAX R D) has been investigating methods for improving the reactivity and durability of the zinc ferrite desulfurization sorbent. Zinc ferrite sorbents are intended for use in desulfurization of hog coal gas in integrated gasification combined cycle (IGCC) or molten carbonate fuel cell (MCFC) applications. The reactivity of the sorbent may be defined as its sulfur sorption capacity at the breakthrough point in a bench-scale fixed-bed reactor. The durability may be defined as the ability of the sorbent to maintain its reactivity and other important physical characteristics such as size, strength, and specific surface area during 10 cycles of sulfidation and regeneration. Two base case sorbents, spherical pellets and cylindrical extrudes used in related METC sponsored projects, are being used to provide a basis for the comparison of physical characteristics and chemical reactivity.
Date: October 27, 1987
Creator: Jha, M. C. & Berggren, M. H.
Object Type: Report
System: The UNT Digital Library
Upper limits on neutron bursts emitted from Ti pressurized D sub 2 gas cells (open access)

Upper limits on neutron bursts emitted from Ti pressurized D sub 2 gas cells

In a search for bursts of neutrons from Ti in pressurized D{sub 2} gas cells, no statistically significant deviations from the background were observed for events where five or more neutrons are detected over a ten day experiment, including 103 hours of counting with cells on, and 28 hours counting of various backgrounds. Up to four cells were used including some 60 grams of 662-Ti fillings in a pressurized cylinder with 40-60 atmosphere of D{sub 2} gas. Other Ti samples were used too. The samples were cooled to liquid nitrogen temperature and placed in front of the neutron detector while warming up to room temperature. Seven cooling cycles were used, for each sample. The neutron detector system included 12 liquid scintillator neutron detectors, arranged in a close packed geometry, with six detectors in the upper hemisphere and six in the lower hemisphere. A central detector placed 2 cm from the cells was used, in each hemisphere, as a scatterer for a time of flight coincidence measurement, yielding the total coincidence efficiency of {epsilon}=2{plus minus}1%. The system was also used in singles mode to allow for counting with large efficiency. A neutron event is characterized by measuring its pulse heights, pulse …
Date: October 27, 1989
Creator: Rugari, S. L.; France, R. H., III; Gai, M.; Lund, B. J.; Smolen, S. D.; Zhao, Z. et al.
Object Type: Report
System: The UNT Digital Library
Three-dimensional temperature history of a multipass, filled weldment. Part 1 (open access)

Three-dimensional temperature history of a multipass, filled weldment. Part 1

A conceptual model is developed for the three-dimensional temperature history of a multipass, filled weldment. Property variations with temperature and phase change are included. A mathematical model and finite difference equations are derived from the conceptual model and a solution procedure for the equations is presented.
Date: October 27, 1976
Creator: Kleinschmidt, D. E.; Trinh, T. & Troiano, R.A.
Object Type: Report
System: The UNT Digital Library
Impedance calculations for power cables to primary coolant pump motors (open access)

Impedance calculations for power cables to primary coolant pump motors

The LOFT primary system motor generator sets are located in Room B-239 and are connected to the primary coolant pumps by means of a power cable. The calculated average impedance of this cable is 0.005323 ohms per unit resistance and 0.006025 ohms per unit reactance based on 369.6 kVA and 480 volts. The report was written to show the development of power cable parameters that are to be used in the SICLOPS (Simulation of LOFT Reactor Coolant Loop Pumping System) digital computer program as written in LTR 1142-16 and also used in the pump coastdowns for the FSAR Analysis.
Date: October 27, 1977
Creator: Hegerhorst, K.B.
Object Type: Report
System: The UNT Digital Library
Use of the Egret instrument in studies of the origin of the cosmic radiation (open access)

Use of the Egret instrument in studies of the origin of the cosmic radiation

This is a continuation of previous studies aimed at predicting spectral signatures of discrete cosmic-ray sources. In this paper, a formalism is developed for calculating gamma-ray spectra observed at Earth from the decay of neutral pions formed in collisions of cosmic-ray protons and ions with galactic gas and dust. The cosmic rays are assumed to be emitted by discrete sources, and their intensities and spectra are described by solutions to a diffusion equation. Calculations of spectral signatures expected from these hypothetical point sources of cosmic rays are presented. In particular, a steady source of cosmic rays could show a harder gamma-ray spectrum than the spectrum of the diffuse galactic background, whereas an impulsive source of cosmic rays could show a much softer spectrum. Observations of the angular variations of gamma-ray intensities and spectra near point sources will provide information on cosmic-ray propagation in other parts of our galaxy, as well as on the nature of the discrete sources themselves. Capabilities of the Egret telescope in mapping spectra from cosmic-ray point sources are briefly discussed. 14 refs., 2 figs.
Date: October 27, 1989
Creator: Dermer, C. D.
Object Type: Article
System: The UNT Digital Library
Low-pressure ion source (open access)

Low-pressure ion source

A low pressure ion source for a neutron source comprises a filament cathode and an anode ring. Approximately 150V is applied between the cathode and the anode. Other electrodes, including a heat shield, a reflector and an aperture plate with a focus electrode, are placed at intermediate potentials. Electrons from the filament drawn out by the plasma and eventually removed by the anode are contained in a magnetic field created by a magnet ring. Ions are formed by electron impact with deuterium or tritium and are extracted at the aperture in the focus electrode. The ion source will typically generate a 200 mA beam through a 1.25 cm/sup 2/ aperture for an arc current of 10A. For deuterium gas, the ion beam is over 50 percent D/sup +/ with less than 1% impurity. The current density profile across the aperture will typically be uniform to within 20%.
Date: October 27, 1982
Creator: Bacon, F.M.; Brainard, J.P.; O'Hagan, J.B. & Walko, R.J.
Object Type: Text
System: The UNT Digital Library
Detection and Measurement of Curium in the Marine Environment (open access)

Detection and Measurement of Curium in the Marine Environment

Transuranium elements have been introduced to the environment by a variety of ways including fallout from weapons testing, leakage from nuclear power reactors, waste effluent from nuclear fuel processing and leakage of radioactive waste from ocean dump sites. Several methods of curium detection and analysis in samples from marine ecosystems are contrasted and discussed in this paper.
Date: October 27, 1978
Creator: Schneider, D. L. & Livingston, H. D.
Object Type: Article
System: The UNT Digital Library
A THERMAL MODEL OF THE IMMOBILIZATION OF LOW-LEVEL RADIOACTIVE WASTE AS GROUT IN CONCRETE VAULTS (open access)

A THERMAL MODEL OF THE IMMOBILIZATION OF LOW-LEVEL RADIOACTIVE WASTE AS GROUT IN CONCRETE VAULTS

Salt solution will be mixed with cement and flyash/slag to form a grout which will be immobilized in above ground concrete vaults. The curing process is exothermic, and a transient thermal model of the pouring and curing process is herein described. A peak temperature limit of 85 C for the curing grout restricts the rate at which it can be poured into a vault. The model is used to optimize the pouring.
Date: October 27, 2008
Creator: Shadday, M
Object Type: Article
System: The UNT Digital Library
FRONT-END ASIC FOR A SILICON COMPTON TELESCOPE. (open access)

FRONT-END ASIC FOR A SILICON COMPTON TELESCOPE.

We describe a front-end application specific integrated circuit (ASIC) developed for a silicon Compton telescope. Composed of 32 channels, it reads out signals in both polarities from each side of a Silicon strip sensor, 2 mm thick 27 cm long, characterized by a strip capacitance of 30 pF. Each front-end channel provides low-noise charge amplification, shaping with a stabilized baseline, discrimination, and peak detection with an analog memory. The channels can process events simultaneously, and the read out is sparsified. The charge amplifier makes uses a dual-cascode configuration and dual-polarity adaptive reset, The low-hysteresis discriminator and the multi-phase peak detector process signals with a dynamic range in excess of four hundred. An equivalent noise charge (ENC) below 200 electrons was measured at 30 pF, with a slope of about 4.5 electrons/pF at a peaking time of 4 {micro}s. With a total dissipated power of 5 mW the channel covers an energy range up to 3.2 MeV.
Date: October 27, 2007
Creator: DE GERONIMO,G.; FRIED, J.; FROST, E.; PHLIPS, B.; VERNON, E. & WULF, E.A.
Object Type: Article
System: The UNT Digital Library
Do grain boundaries in nanophase metals slide? (open access)

Do grain boundaries in nanophase metals slide?

Nanophase metallic materials show a maximum in strength as grain size decreases to the nano scale, indicating a break down of the Hall-Petch relation. Grain boundary sliding, as a possible accommodation mechanisms, is often the picture that explain computer simulations results and real experiments. In a recent paper, Bringa et al. Science 309, 1838 (2005), we report on the observation of an ultra-hard behavior in nanophase Cu under shock loading, explained in terms of a reduction of grain boundary sliding under the influence of the shock pressure. In this work we perform a detailed study of the effects of hydrostatic pressure on nanophase Cu plasticity and find that it can be understood in terms of pressure dependent grain boundary sliding controlled by a Mohr-Coulomb law.
Date: October 27, 2006
Creator: Bringa, E M; Leveugle, E & Caro, A
Object Type: Article
System: The UNT Digital Library
SEMATECH EUV resist benchmarking results (open access)

SEMATECH EUV resist benchmarking results

Extreme Ultraviolet Lithography (EUVL) is one of the leading candidates for next generation lithography technology for the 32 nm HP and beyond. The availability of EUV resists is one of the most significant challenges facing its commercialization. To accelerate EUV resist development, SEMATECH provides access to two exposure tools: (1) The EUV Resist Test Center (RTC) at SEMATECH at the University at Albany, SUNY, NY; and (2) the SEMATECH microexposure tools (ALS-MET) at Lawrence Berkeley National Laboratory (LBNL).
Date: October 27, 2007
Creator: Ma, Andy; Park, Joo-On; Dean, Kim; Wurm, Stefan & Naulleau, Patrick
Object Type: Article
System: The UNT Digital Library
Understanding Modern Magnets through Conformal Mapping (open access)

Understanding Modern Magnets through Conformal Mapping

When I had to choose, within some narrow range, the topic of this paper, I received great help from a colleague in Berkeley and from Prof. Little when it was suggested that I should pick among the possible subjects of my talk the subject that Prof. Bloch would have enjoyed most. Since Prof. Bloch would prefer a scalpel over a sword every time, I hope and think that most people will approve my choice. When one intends to talk about a subject that is as old as conformal mapping and one does not want to lose the audience in a very short time, it is advisable to start by explaining both the motivation for the talk as well as the goals one has in mind when giving the talk. This particular talk has been motivated by the increasing frequency with which one hears, from people that ought to know better, statements like: 'Conformal mapping is really a thing of the past because of all the marvelous computer programs that we now have'. Even though, or more likely because, I have been intimately involved in the development of some large and widely used computer codes, I am deeply disturbed by such …
Date: October 27, 1989
Creator: Halbach, K.
Object Type: Article
System: The UNT Digital Library
FRONT-END ASIC FOR HIGH RESOLUTION X-RAY SPECTROMETERS. (open access)

FRONT-END ASIC FOR HIGH RESOLUTION X-RAY SPECTROMETERS.

We present an application specific integrated circuit (ASIC) for high-resolution x-ray spectrometers. The ASIC is designed to read out signals from a pixelated silicon drift detector (SDD). Each hexagonal pixel has an area of 15 mmz and an anode capacitance of less than 100 fF. There is no integrated Field Effect transistor (FET) in the pixel, rather, the readout is done by wirebonding the anodes to the inputs of the ASIC. The ASIC provides 14 channels of low-noise charge amplification, high-order shaping with baseline stabilization, and peak detection with analog memory. The readout is sparse and based on low voltage differential signaling. An interposer provides all the interconnections required to bias and operate the system. The channel dissipates 1.6 mW. The complete 14-pixel unit covers an area of 210 mm{sup 2}, dissipates 12 mW cm{sup -2}, and can be tiled to cover an arbitrarily large detection area. We measured a preliminary resolution of 172 eV at -35 C on the 6 keV peak of a {sup 55}Fe source.
Date: October 27, 2007
Creator: De Geronimo,G.; Chen, W.; Fried, J.; Li, Z.; Pinelli, D. A.; Rehak, P. et al.
Object Type: Article
System: The UNT Digital Library
nu-TRLan User Guide Version 1.0: A High-Performance Software Package for Large-Scale Harmitian Eigenvalue Problems (open access)

nu-TRLan User Guide Version 1.0: A High-Performance Software Package for Large-Scale Harmitian Eigenvalue Problems

The original software package TRLan, [TRLan User Guide], page 24, implements the thick restart Lanczos method, [Wu and Simon 2001], page 24, for computing eigenvalues {lambda} and their corresponding eigenvectors v of a symmetric matrix A: Av = {lambda}v. Its effectiveness in computing the exterior eigenvalues of a large matrix has been demonstrated, [LBNL-42982], page 24. However, its performance strongly depends on the user-specified dimension of a projection subspace. If the dimension is too small, TRLan suffers from slow convergence. If it is too large, the computational and memory costs become expensive. Therefore, to balance the solution convergence and costs, users must select an appropriate subspace dimension for each eigenvalue problem at hand. To free users from this difficult task, nu-TRLan, [LNBL-1059E], page 23, adjusts the subspace dimension at every restart such that optimal performance in solving the eigenvalue problem is automatically obtained. This document provides a user guide to the nu-TRLan software package. The original TRLan software package was implemented in Fortran 90 to solve symmetric eigenvalue problems using static projection subspace dimensions. nu-TRLan was developed in C and extended to solve Hermitian eigenvalue problems. It can be invoked using either a static or an adaptive subspace dimension. In …
Date: October 27, 2008
Creator: Yamazaki, Ichitaro; Wu, Kesheng & Simon, Horst
Object Type: Report
System: The UNT Digital Library
READOUT ASIC FOR 3D POSITION-SENSITIVE DETECTORS. (open access)

READOUT ASIC FOR 3D POSITION-SENSITIVE DETECTORS.

We describe an application specific integrated circuit (ASIC) for 3D position-sensitive detectors. It was optimized for pixelated CZT sensors, and it measures, corresponding to an ionizing event, the energy and timing of signals from 121 anodes and one cathode. Each channel provides low-noise charge amplification, high-order shaping, along with peak- and timing-detection. The cathode's timing can be measured in three different ways: the first is based on multiple thresholds on the charge amplifier's voltage output; the second uses the threshold crossing of a fast-shaped signal; and the third measures the peak amplitude and timing from a bipolar shaper. With its power of 2 mW per channel the ASIC measures, on a CZT sensor Connected and biased, charges up to 100 fC with an electronic resolution better than 200 e{sup -} rms. Our preliminary spectral measurements applying a simple cathode/mode ratio correction demonstrated a single-pixel resolution of 4.8 keV (0.72 %) at 662 keV, with the electronics and leakage current contributing in total with 2.1 keV.
Date: October 27, 2007
Creator: DE GERONIMO,G.; VERNON, E.; ACKLEY, K.; DRAGONE, A.; FRIED, J.; OCONNOR, P. et al.
Object Type: Article
System: The UNT Digital Library
Program plan for molten carbonate fuel-cell systems development (open access)

Program plan for molten carbonate fuel-cell systems development

The purpose of this document is to describe in both programmatic and technical terms the methodology that the US Department of Energy will use to commercialize a molten carbonate fuel cell power plant. Responsibility for the planning and management of the program resides in the molten carbonate fuel cell program office at the Argonne National Laboratory which reports to the Assistant Director for Fuel Cells in the Division of Fossil Fuel utilization of DOE/FE. The actual development of technology is carried out by selected contractors. The technology development phase of the program will culminate with the construction and operation of two demonstration power plants. The first power plant will be an industrial cogeneration plant which will be completed in 1987. The other power plant will be a baseload electric power plant to be completed in 1989.
Date: October 27, 1978
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Signals from cosmic ray sources, some statistical issues (open access)

Signals from cosmic ray sources, some statistical issues

The possible existence of discrete sources of cosmic rays is presently one of the main topics of study in non-accelerator particle physics. The search is being conducted in a wide variety of experiments using UHE-{gamma} rays, VHE-{gamma} rays, EeV particles, underground {mu}'s and {nu}'s. The current experimental situation, however, can be described as chaotic. The number of claimed observations of sources by different groups using a variety of experimental techniques is quite large, but a consistent interpretation of the various results has failed to emerge. Most of the observations rely on either on dc excess'' from the direction of the source, a periodicity of the events from that direction, or some combination of these two effects. In the first section of this paper, we discuss some of the techniques that may be used in searching for a dc excess. We review two common bin free tests of the light curves. We discuss a particular problem involving phase coherence when doing a period search. This paper discusses some of the issues and meanings involved in combining probabilities from more than one test. Prescribing the right'' way to do analysis is certainly beyond this paper's scope. However some of the issues and …
Date: October 27, 1990
Creator: Goodman, M.
Object Type: Article
System: The UNT Digital Library
Category I structures program. [PWR; BWR] (open access)

Category I structures program. [PWR; BWR]

The objective of the Category I Structure Program is to supply experimental and analytical information needed to assess the structural capacity of Category I structures (excluding the reactor cntainment building). Because the shear wall is a principal element of a Category I structure, and because relatively little experimental information is available on the shear walls, it was selected as the test element for the experimental program. The large load capacities of shear walls in Category I structures dictates that the experimental tests be conducted on small size shear wall structures that incorporates the general construction details and characteristics of as-built shear walls.
Date: October 27, 1981
Creator: Endebrock, E.G. & Dove, R.C.
Object Type: Article
System: The UNT Digital Library
Tandem mirror next step: remote maintenance (open access)

Tandem mirror next step: remote maintenance

This study of the next proposed experiment in the Mirror Fusion Program, the Tandem Mirror Next Step (TMNS), has included serious consideration of the maintenance requirements of such a large source of high energy neutrons with its attendant throughput of tritium. Although maintenance will be costly in time and money, our conclusion is that with careful attention to a design for maintenance plan such a device can be reliably operated.
Date: October 27, 1980
Creator: Doggett, J. N.; Damm, C. C. & Hanson, C. L.
Object Type: Article
System: The UNT Digital Library
Fundamental mechanisms in flue gas conditioning (open access)

Fundamental mechanisms in flue gas conditioning

This project is divided into four tasks. We developed our management plan in Task 1. Task 2, evaluation of mechanisms in FGD sorbent and ash interactions, focuses on characteristics of binary mixtures of these distinct powders. Task 3, evaluation of mechanisms in conditioning agents and ash, is designed to examine effects of various conditioning agents on fine ash particles to determine mechanisms by which these agents alter physical properties of ash. We began Tasks 2 and 3 with an extensive literature search and assembly of existing theories. We completed this phase of the project with publication of two special Topical Reports. Our laboratory analyses during the past quarter covered a variety of topics. We quantified increases in surface area, changes in particle morphology, and increases in cohesivity that result when sorbents are mixed with ashes. Measurements of water content illustrated the increased tendency of the mixtures to adsorb and absorb water. Our analyses of leached and unleached dust cake ashes provided some interesting insights into effects that compounds adsorbed on surfaces of ash particles can have on bulk ash behavior. We also observed the effects that pozzolanic reactions can have on ash resistivity. Initial examinations of outputs of the SRI-EPA …
Date: October 27, 1992
Creator: Snyder, T. R. & Vann Bush, P.
Object Type: Report
System: The UNT Digital Library
Geometry of wave electromagnetics (open access)

Geometry of wave electromagnetics

A challenge to the commonly held view of light as a wave phenomenon is presented. An exact realization of light as generalized pencils or rays is constructed, with stress placed on using pencils of rays rather than single rays. Exact equations of motion are presented for the rays in the pencil, and these rays tend to travel in straight lines in empty space (not too near the edge of the beam). (GHT)
Date: October 27, 1980
Creator: Sudarshan, E. C.G.
Object Type: Report
System: The UNT Digital Library
Ten channel filter-fluorescer spectrometer (open access)

Ten channel filter-fluorescer spectrometer

A ten channel filter-fluorescer spectrometer was designed for measuring x-ray spectra from 2 to 115 keV at the Argus and Shiva laser facilities. Previously x-ray spectra were measured with filtered detectors; however, the higher fluxes and more complicated spectra observed in recent experiments requires the greater photon energy definition of this technique. Five filter-detector channels are also incorporated in the spectrometer for measuring low intensity sources. Five Pb-filtered detectors will be used for obtaining spectral information for energies greater than 100 keV. Provisions are being made to automate this diagnostic to produce the x ray spectrum minutes after shot time.
Date: October 27, 1978
Creator: Pruett, B.L.; Tirsell, K.G.; Kornblum, H.N.; Glaros, S.S.; Campbell, D.E. & Slivinsky, V.W.
Object Type: Article
System: The UNT Digital Library
Alternative oxide fuel pellet fabrication for irradiation testing. [LMFBR] (open access)

Alternative oxide fuel pellet fabrication for irradiation testing. [LMFBR]

Fabrication of experimental breeder reactor fuel pellets by the common cold-press-and-sinter technique for irradiation testing in EBR-II is discussed. Fuel types include mixed thoria-plutonia, UO/sub 2/ enriched with 22 weight percent /sup 233/U in U, UO/sub 2/ enriched with thirty-four weight percent /sup 235/U in U, and mixed urania-plutonia.
Date: October 27, 1978
Creator: Rasmussen, D. E.; Jentzen, W. R. & McCord, R. B.
Object Type: Article
System: The UNT Digital Library