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open access

A Compton scatter camera for spectral imaging of 0.5 to 3.0 MeV gamma rays

Description: A prototype Compton scatter camera for imaging gamma rays has been built and tested. This camera addresses unique aspects of gamma-ray imaging at nuclear industrial sites, including gamma-ray energies in the 0.5 to 3.0 MeV range and polychromatic fields. Analytic models of camera efficiency, resolution and contaminating events are developed. The response of the camera bears strong similarity to emission computed tomography devices used in nuclear medicine. A direct Fourier based algorithm is de… more
Date: December 31, 1994
Creator: Martin, J.B.
open access

An experimental study of fluidelastic instability and draf force on a tube in two-phase cross flow

Description: Two-phase cross flow over heat exchanger tubes creates vibrations which contribute greatly to the wear on the tubes. Fluidelastic instability is a major mechanism by which tubes can fail. In this work, the fluidelastic instability of a tube placed in an array subjected to two-phase cross flow has been studied. For the determination of fluidelastic instability, a triangular tube array was used. The tubes were made of acrylic and were 2.2 cm or 2.37 cm in diameter and 20 cm in length. Eighteen tu… more
Date: December 31, 1994
Creator: Joo, Youngcheol
open access

Magnetohydrodynamic simulations of noninductive helicity injection in the reversed-field pinch and tokamak

Description: Numerical computation is used to investigate resistive magnetohydrodynamic (MHD) fluctuations in the reversed-field pinch (RFP) and in tokamak-like configurations driven solely by direct current (DC) helicity injection. A Lundquist number (S) scan of RFP turbulence without plasma pressure produces the weak scaling of S{sup -0.18} for the root-mean-square magnetic fluctuation level for 2.5x10{sup 3}{le}S{le}4x10{sup 4}. The temporal behavior of fluctuations and the reversal parameter becomes mor… more
Date: December 31, 1995
Creator: Sovinec, C. R.
open access

A Compton camera for spectroscopic imaging from 100 keV to 1 MeV

Description: A review of spectroscopic imaging issues, applications, and technology is presented. Compton cameras based on solid state semiconductor detectors stands out as the best system for the nondestructive assay of special nuclear materials. A camera for this application has been designed based on an efficient specific purpose Monte Carlo code developed for this project. Preliminary experiments have been performed which demonstrate the validity of the Compton camera concept and the accuracy of the cod… more
Date: December 31, 1998
Creator: Earnhart, J. R. D.
open access

Effects of modeled terms in the Reynolds-stress transport equations

Description: A discussion of the origins and interpretation of various previously proposed models for the terms in the incompressible Reynolds-stress equation is given. It is hoped that the interpretations will provoke thoughts that will help in the future modeling of Reynolds-stress transport equations. Different forms of the closed Reynolds-stress equation have been solved numerically for the given mean velocity field of the wake flow behind a flat plate at a Reynolds number of 1000. A finite-difference/f… more
Date: December 31, 1993
Creator: Linn, R.R.
open access

An experimental investigation of two-phase crossflow over rigidly and flexibly mounted tubes

Description: Two-phase crossflow over heat exchanger tubes induces vibrations which contribute greatly to the wear on the tubes. Of the three mechanisms leading to two-phase flow-induced vibrations which have been identified, fluid-elastic instability has been recognized as that which leads to the vibrations with the largest amplitude. The mass damping parameter is used to predict the onset of fluid-elastic instability, and the mean drag coefficient is used to calculate the mass damping parameter. In this t… more
Date: December 31, 1991
Creator: Gerhart, S.M.
open access

Cross flow induced vibrations in staggered arrays of cylindrical structures

Description: Flow induced vibrations cause by instability is the subject of this investigation. The bulk of the work performed is theoretical in nature, the comparison with some of existing experimental data is given for each of four models described. First model encompasses the effects of prescribed motion on the cylinder. Such circumstances occur in the case of vortex shedding initiated instability. The reduced velocity within the cylinder array is low and there is no coupling between the adjacent cylinde… more
Date: December 31, 1991
Creator: Marn, J.
open access

A Precision Measurement of the Z{sup 0} Lineshape Parameters for the Process Z{sup 0} {r_arrow} {tau}{sup +}{tau}{sup {minus}}

Description: In this dissertation, a measurement of the partial decay width of the process Z{sup 0} {r_arrow} {tau}{sup +}{tau}{sup {minus}} using data collected during 1993 and 1994 at the OPAL detector at CERN is described. The cross sections of this process at three center-of-mass energies near the Z{sup 0} resonance were determined, and from a fit to those cross sections, the mass of the Z{sup 0}, its total decay width and its partial decay width into {tau}{sup +}{tau}{sup {minus}} final states were det… more
Date: December 31, 1996
Creator: Lahmann, R.
open access

Compressive strength, plastic flow properties, and surface frictional effects of 1100, 3003 and 6061 aluminum alloys

Description: The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cyl… more
Date: December 31, 1993
Creator: Pinkerton, G.W.
open access

Measurements of granular flow dynamics with high speed digital images

Description: The flow of granular materials is common to many industrial processes. This dissertation suggests and validates image processing algorithms applied to high speed digital images to measure the dynamics (velocity, temperature and volume fraction) of dry granular solids flowing down an inclined chute under the action of gravity. Glass and acrylic particles have been used as granular solids in the experiment. One technique utilizes block matching for spatially averaged velocity measurements of the … more
Date: December 31, 1994
Creator: Lee, J.
open access

Measurement of particle speed through optical reflective sensing

Description: Two methods determine the speed of 3 m glass spheres using optical reflective sensors embedded in a micro-processor system. The first method, which will be referred to as the one pulse method, is sensitive to particle size and shape. The pulse width of a detected particle is measured and normalized by a shape correction factor resulting in a speed estimate. Three models are developed to correct for effects due to particle shape and light scattering inhomogeneities. The second method, which will… more
Date: December 31, 1993
Creator: McCardle, J.
open access

Synthesis of organosilicon compounds

Description: Silicon-containing polymers have been a focus of synthesis and study in Dr. Barton`s group because of their chemistry and properties which are not offered by other systems or materials. For example, the polymer -[-SiMe{sub 2}C{triple_bond}C-]{sub n}-can be easily processed to films or fibers from melt or solution, and thermally converted to a SiC-containing ceramic in high yield at high temperature. In recent years, carbosilane dendritic polymers have been of great interests in many research gr… more
Date: December 31, 1996
Creator: Zhao, G.
open access

Studies of the terrestrial O{sub 2} and carbon cycles in sand dune gases and in biosphere 2

Description: Molecular oxygen in the atmosphere is coupled tightly to the terrestrial carbon cycle by the processes of photosynthesis, respiration, and burning. This dissertation examines different aspects of this coupling in four chapters. Chapter 1 explores the feasibility of using air from sand dunes to reconstruct atmospheric O{sub 2} composition centuries ago. Such a record would reveal changes in the mass of the terrestrial biosphere, after correction for known fossil fuel combustion, and constrain th… more
Date: December 31, 1995
Creator: Severinghaus, J.P.
open access

{sup 222}Rn in water: A comparison of two sample collection methods and two sample transport methods, and the determination of temporal variation in North Carolina ground water

Description: Objectives of this field experiment were: (1) determine whether there was a statistically significant difference between the radon concentrations of samples collected by EPA`s standard method, using a syringe, and an alternative, slow-flow method; (2) determine whether there was a statistically significant difference between the measured radon concentrations of samples mailed vs samples not mailed; and (3) determine whether there was a temporal variation of water radon concentration over a 7-mo… more
Date: December 31, 1994
Creator: Hightower, J. H., III
open access

Modeling the effects of atmospheric emissions on groundwater composition

Description: A composite model of atmospheric, unsaturated and groundwater transport is developed to evaluate the processes determining the distribution of atmospherically derived contaminants in groundwater systems and to test the sensitivity of simulated contaminant concentrations to input parameters and model linkages. One application is to screen specific atmospheric emissions for their potential in determining groundwater age. Temporal changes in atmospheric emissions could provide a recognizable patte… more
Date: December 31, 1994
Creator: Brown, T. J.
open access

Evaluation of low-level radioactive waste characterization and classification programs of the West Valley Demonstration Project

Description: The West Valley Demonstration Project (WVDP) is preparing to upgrade their low-level radioactive waste (LLW) characterization and classification program. This thesis describes a survey study of three other DOE sites conducted in support of this effort. The LLW characterization/classification programs of Oak Ridge National Laboratory, Savannah River Site, and Idaho National Engineering Laboratory were critically evaluated. The evaluation was accomplished through tours of each site facility and p… more
Date: December 31, 1994
Creator: Taie, K.R.
open access

MagRad: A code to optimize the operation of superconducting magnets in a radiation environment

Description: A powerful computational tool, called MagRad, has been developed which optimizes magnet design for operation in radiation fields. Specifically, MagRad has been used for the analysis and design modification of the cable-in-conduit conductors of the TF magnet systems in fusion reactor designs. Since the TF magnets must operate in a radiation environment which damages the material components of the conductor and degrades their performance, the optimization of conductor design must account not only… more
Date: December 31, 1995
Creator: Yeaw, Christopher T.
open access

Analysis of offsite dose calculation methodology for a nuclear power reactor

Description: This technical study reviews the methodology for calculating offsite dose estimates as described in the offsite dose calculation manual (ODCM) for Pennsylvania Power and Light - Susquehanna Steam Electric Station (SSES). An evaluation of the SSES ODCM dose assessment methodology indicates that it conforms with methodology accepted by the US Nuclear Regulatory Commission (NRC). Using 1993 SSES effluent data, dose estimates are calculated according to SSES ODCM methodology and compared to the dos… more
Date: December 31, 1995
Creator: Moser, D.M.
open access

Evaluating open-path FTIR spectrometer data using different quantification methods, libraries, and background spectra obtained under varying environmental conditions

Description: Studies were performed to evaluate the accuracy of open-path Fourier Transform Infrared (OP-FTIR) spectrometers using a 35 foot outdoor exposure chamber in Pittsboro, North Carolina. Results obtained with the OP-FTIR spectrometer were compared to results obtained with a reference method (a gas chromatograph equipped with a flame ionization detector, GC-FID). Concentration results were evaluated in terms of the mathematical methods and spectral libraries used for quantification. In addition, the… more
Date: December 31, 1995
Creator: Tomasko, M.S.
open access

Microdosimetric investigations at the Fast Neutron Therapy Facility at Fermilab

Description: Microdosimetry was used to investigate three issues at the neutron therapy facility (NTF) at Fermilab. Firstly, the conversion factor from absorbed dose in A-150 tissue equivalent plastic to absorbed dose in ICRU tissue was determined. For this, the effective neutron kerma factor ratios, i.e. oxygen tissue equivalent plastic and carbon to A-150 tissue equivalent plastic, were measured in the neutron beam. An A-150 tissue equivalent plastic to ICRU tissue absorbed dose conversion factor of 0.92 … more
Date: December 31, 1997
Creator: Langen, K.M.
open access

Studies of structures and phase transitions in pyrrhotite

Description: This report contains a general introduction, the experimental section, general conclusions, and two appendices: using projection operators to construct the basis functions and the magnetic transition of bulk pyrrhotite samples in the low-temperature range. Four chapters have been removed for separate processing. They are: From pyrrhotite to troilite: An application of the Landau theory of phase transitions; Phase transition in near stoichiometric iron sulfide; A ordering, incommensuration and p… more
Date: March 31, 1997
Creator: Li, F.
open access

Spatio-temporal statistical models with applications to atmospheric processes

Description: This doctoral dissertation is presented as three self-contained papers. An introductory chapter considers traditional spatio-temporal statistical methods used in the atmospheric sciences from a statistical perspective. Although this section is primarily a review, many of the statistical issues considered have not been considered in the context of these methods and several open questions are posed. The first paper attempts to determine a means of characterizing the semiannual oscillation (SAO) s… more
Date: December 31, 1996
Creator: Wikle, C.K.
open access

Study of temporal variation of radon concentrations in public drinking water supplies

Description: The Environmental Protection Agency (EPA) has proposed a Maximum Contaminant Level (MCL) for radon-222 in public drinking water supplies of 300 pCi/L. Proposed monitoring requirements include collecting quarterly grab samples for the first year, then annual samples for the remainder of the compliance cycle provided first year quarterly samples average below the MCL. The focus of this research was to study the temporal variation of groundwater radon concentrations to investigate how reliably one… more
Date: December 31, 1995
Creator: York, E. L.
open access

Analysis of stray radiation produced by the advanced light source (1.9 GeV synchrotron radiation source) at Lawrence Berkeley Laboratory

Description: The yearly environmental dose equivalent likely to result at the closest site boundary from the Advanced Light Source was determined by generating multiple linear regressions. The independent variables comprised quantified accelerator operating parameters and measurements from synchronized, in-close (outside shielding prior to significant atmospheric scattering), state-of-the-art neutron remmeters and photon G-M tubes. Neutron regression models were more successful than photon models due to low… more
Date: December 31, 1995
Creator: Ajemian, R. C.
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