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Acculturation and Locus Of Control: Their Relationship to the Use of Inhalants

Description: This study analyzed the effects of acculturation, locus of control, and incidence of inhalant use on Mexican Americans. Information was collected from 275 subjects at three middle schools and one treatment center. The instrument consisted of Levenson's Locus of Control Scale, the Acculturation Rating Scale for Mexican Americans, and an incidence of use and family relationship questionnaire developed for this study. Statistical analysis indicated a relationship between acculturation and inhalant use. Further examination revealed relationships between a family members' use and subjects' inhalant use; subjects' alcohol use and inhalant use; and subjects' marijuana use and inhalant use. Information implied that prevention and intervention programs should focus on children of substance users and further research is needed surrounding the role of acculturation.
Date: July 1989
Creator: Davis, Lynn Matthew
Partner: UNT Libraries

A.B. Marx's Concept of Rondo and Sonata: A Critical Evaluation of His Explanations of Musical Form

Description: The third volume of A.B. Marx's theory treatise Die Lehre von der musikalischen Komposition is discussed. His definitions of rondo and sonata formal types are demonstrated in the first chapter in addition to the manner of their derivation through a developmental process originating in the Liedform. Musical examples chosen by Marx are examined in chapter two. These examples, taken from Mozart's and Beethoven's piano works, are evaluated in relation to Marx's definitions of the various types of form. The third chapter is concerned with the progression from microstructure to macrostructure and the functional interrelation of the parts to the whole. In addition, Marx's opinion on musical form is compared with perspectives of philosophers from his time period and the immediate past.
Date: July 1993
Creator: Lang, Adelheid K.
Partner: UNT Libraries

The Use of the Power Method to Find Dominant Eigenvalues of Matrices

Description: This paper is the result of a study of the power method to find dominant eigenvalues of square matrices. It introduces ideas basic to the study and shows the development of the power method for the most well-behaved matrices possible, and it explores exactly which other types of matrices yield to the power method. The paper also discusses a type of matrix typically considered impossible for the power method, along with a modification of the power method which works for this type of matrix. It gives an overview of common extensions of the power method. The appendices contain BASIC versions of the power method and its modification.
Date: July 1992
Creator: Cavender, Terri A.
Partner: UNT Libraries

The Chlorination of Amino Acid in Municipal Waste Effluents

Description: In model reaction systems to test amino acids in chlorinated waste effluents, several amino acids were chlorinated at high chlorine doses. (2000-4000 mg/1). Amino acids present in municipal waste effluents before and after chlorination were concentrated and purified using cation exchange and Chelex resins. After concentration and cleanup of the samples, the amino acids were derivatized by esterification of the acid functional groups and acylation of the amine groups. Identification and quantification of the amino acids and chlorination products was carried out by gas chromatography/mass spectrometry, using a digital computer data system. Analysis of the waste products revealed the presence of new carbon-chlorine bonded derivatives of the amino acid tyrosine when the effluents were treated with heavy doses of chlorine.
Date: July 1977
Creator: Burleson, Jimmie L.
Partner: UNT Libraries

The History of the Development of Public School Music in Taylor County, Texas

Description: The first of any formal education in music that can be found from the records or from the memories of those who were present at the time was the singing school. One ranch in the Blair community has files in which records were found of all import ant events of the school and community life. These files relate the coming of the singing school regularly every summer. Shaped notes were taught front hymn books. At the end of the course, a certificate was given to those who graduated. The teacher of the school then moved on to the next engagement.
Date: July 1943
Creator: Moore, Katrina Lee
Partner: UNT Libraries

An Analytical Critique of the Use of Twelve Equal Tones as Utilized in "Sonata-Fantasia" by George Rochberg

Description: This thesis centers around a certain twentieth-century compositionaI device, the method of composition with twelve tones. There are many terms to designate this device, for example: "basic set," "tone-row," "note-series," "serialism," "serial technique," "twelve-note series," "twelve-tone technique" or "twelve-tone method." TI is thesis is a methodical research demonstrating the contemporary conventional way of scientifically and artfully manipulating twelve equal tempered degrees of the chromatic scale to produce a desirable system. In order to arrive at any substantial conclusions, it is necessary to make a critical examination and evaluation of known twelve-tone compositional procedures from as many angles as possible, so as virtually to exhaust every practical and speculative potentiality included in the technique, that is, within the range and limits of our present needs. This examination and evaluation will also involve a comparative investigation of various uses of the device, in order to produce and suggest ideas for further theoretical insights. The ultimate purpose of this thesis is to pinpoint the "hows" and "whys" of Rochberg's use of the twelve equal tones in Sonata-Fantasia.
Date: July 1968
Creator: Tiroff, Philip Knight
Partner: UNT Libraries

A Comparison of the Use of Music in the Holy Eucharist of the Roman Catholic Church and the Sabbath Morning Service of the Jewish Synagogue in the Middle Ages

Description: The problem with which this investigation is concerned is that of comparing the medieval musical traditions of two of the world's most influential religions. The similarities are discussed in two major categories: the comparison of liturgical texts and ritual, and the comparison of the music appearing in each ritual. This study has one main purpose. That purpose is to demonstrate how, through musical traditions, each religion has developed through the influence of the other. Samples of the liturgies from the musical portions of the services were obtained from prayer books and references dealing with those religions. Investigations of English translations from the Latin and Hebrew revealed a close identity between the two, not only in scriptural uses, but also in prayers and responses. Musical examples demonstrating similar elements in Hebrew and Christian worship were found in the extensive research of A. Z. Idelsohn and Eric Werner. Due to the dispersal of world Jewry, the best examples of Hebrew medieval music were obtained from the most isolated Jewish communities, such as those of Yemen, Musical similarities included modes, melodic formulas, and hymns and songs. This report concludes that the musical portions of the services of Christianity and Judaism in the Middle Ages were strikingly similar, and their subsequent musical development was strongly influenced by their coexistence.
Date: July 1971
Creator: Simmons, Sandra K. (Sandra Kay)
Partner: UNT Libraries

Seismic imaging of the shallow subsurface with high frequency seismic measurements

Description: Elastic wave propagation in highly heterogeneous media is investigated and theoretical calculations and field measurements are presented. In the first part the dynamic composite elastic medium (DYCEM) theory is derived for one-dimensional stratified media. A self-consistent method using the scattering functions of the individual layers is formulated, which allows the calculation of phase velocity, attenuation and waveform. In the second part the DYCEM theory has been generalized for three-dimensional inclusions. The specific case of spherical inclusions is calculated with the exact scattering functions and compared with several low frequency approximations. In the third part log and VSP data of partially water saturated tuffs in the Yucca Mountain region of Nevada are analyzed. The anomalous slow seismic velocities can be explained by combining self-consistent theories for pores and cracks. The fourth part analyzes an air injection experiment in a shallow fractured limestone, which has shown large effects on the amplitude, but small effects on the travel time of the transmitted seismic waves. The large amplitude decrease during the experiment is mainly due to the impedance contrast between the small velocities of gas-water mixtures inside the fracture and the formation. The slow velocities inside the fracture allow an estimation of aperture and gas concentration profiles.
Date: July 1, 1998
Creator: Kaelin, B.
Partner: UNT Libraries Government Documents Department

Symbolic derivation of high-order Rayleigh-Schroedinger perturbation energies using computer algebra: Application to vibrational-rotational analysis of diatomic molecules

Description: Rayleigh-Schroedinger perturbation theory is an effective and popular tool for describing low-lying vibrational and rotational states of molecules. This method, in conjunction with ab initio techniques for computation of electronic potential energy surfaces, can be used to calculate first-principles molecular vibrational-rotational energies to successive orders of approximation. Because of mathematical complexities, however, such perturbation calculations are rarely extended beyond the second order of approximation, although recent work by Herbert has provided a formula for the nth-order energy correction. This report extends that work and furnishes the remaining theoretical details (including a general formula for the Rayleigh-Schroedinger expansion coefficients) necessary for calculation of energy corrections to arbitrary order. The commercial computer algebra software Mathematica is employed to perform the prohibitively tedious symbolic manipulations necessary for derivation of generalized energy formulae in terms of universal constants, molecular constants, and quantum numbers. As a pedagogical example, a Hamiltonian operator tailored specifically to diatomic molecules is derived, and the perturbation formulae obtained from this Hamiltonian are evaluated for a number of such molecules. This work provides a foundation for future analyses of polyatomic molecules, since it demonstrates that arbitrary-order perturbation theory can successfully be applied with the aid of commercially available computer algebra software.
Date: July 1, 1997
Creator: Herbert, J.M.
Partner: UNT Libraries Government Documents Department

Measurements of delayed neutron parameters for U-235 and Np-237

Description: Delayed neutrons are emitted by excited nuclei formed in beta decay of fission products called delayed neutron precursors. About 1% of the total neutrons released in fission are delayed neutrons; however, this small fraction plays an important role in nuclear reactor control. The delayed neutrons determine the time-dependent behavior of reactors, and knowledge of parameters used to predict neutron emission rate is essential for establishing reactivity worths. The delayed neutron yields, decay constants, and the absolute yield for the six-group delayed neutrons have been measured for U-235 and Np-237. This experiment has been called for in the forecast of experiments needed to support operations in the US. The bare U-235 metal assembly Godiva IV at the Los Alamos Critical Experiment Facility (LACEF) provided the source of neutrons. Godiva IV generated about 10{sup 7} total fissions in the samples for the infinite and instantaneous irradiation needed to accentuate the shorter and longer-lived groups of delayed neutrons. The detection system used in the experiment consisted of 20 He-3 tubes embedded in a polyethylene cylinder. The delayed neutron activity resulting from the fast neutron-induced fission has been measured. The measured absolute yield for U-235 was determined to be 0.0163 {+-} 0.009 neutrons/fission. This value compares very well with the well-established Keepin absolute yield of 0.0165 {+-} 0.0005. The newly measured absolute yield value for Np-237 was 0.0126 {+-} 0.0007, which compares well to the recently reported value of 0.0129 {+-} 0.0004 by Saleh and Parish. The measured values for U-235 are corroborated with period (e-folding time) versus reactivity calculations.
Date: July 1997
Creator: Loaiza, D.
Partner: UNT Libraries Government Documents Department

A study of tearing modes via electron cyclotron emission from tokamak plasmas

Description: This thesis studies several tearing mode problems from both theoretical and experimental points of view. A major part of this thesis is to demonstrate that Electron Cyclotron Emission (ECE) is an excellent diagnostic for studying an MHD mode structure and its properties in a tokamak plasma. It is shown that an MHD mode can be detected from the electron temperature fluctuations measured by ECE. The amplitude and phase profiles of the fluctuations contain detailed information about the mode structure. The ECE fluctuation phase profile indicates the magnetic island deformation due to the combination of sheared flow and viscosity. A model is presented to relate qualitatively the observed phase gradient to the local magnetic field, flow velocity shear and viscosity in a 2D slab geometry, using an ideal Ohm`s law and the plasma momentum equation including flow and viscosity. Numerical solution of the resultant Grad-Shafranov-like equation describing the deformed island shows that the experimentally observed value of the phase gradient can be obtained under realistic parameters for the shear in the flow velocity and viscosity. A new approach to the tearing mode stability boundary and saturation level is also presented.
Date: July 1, 1998
Creator: Ren, C.
Partner: UNT Libraries Government Documents Department

Experimental observations of the breakup of multiple metal jets in a volatile liquid

Description: A postulated severe loss of coolant accident in a nuclear reactor can lead to significant core damage due to residual heat generation. Subsequently, melted core materials (i.e.; corium) could migrate downward and impinge upon the lower head of the reactor pressure vessel (RPV). During this relocation, the complexity of the reactor structure could segregate the molten corium into various flow paths. A perforated flow plate could readily provide the mechanism to segregate the molten corium. The resulting small (a few cm) diameter melt streams, driven by gravity, could then penetrate the remaining coolant in the RPV and cause any of the following events: impingement of the high temperature melt streams on the lower head could breach the RPV; re-agglomeration of the corium melt on the lower head could influence the coolability of the debris bed; {open_quotes}pre-mixing{close_quotes} of the melt streams with the coolant could lead to a vapor explosion; or, sufficient quenching of the melt streams by the coolant could produce a stabilized debris bed. An overview of the thermo-science issues related to core-melt accidents is presented by Theofanous. Thus, insight into the melt stream breakup mechanisms (i.e.; interfacial conditions, fragmentation, and geometric spacing) during the melt-coolant interactions is necessary to evaluate the plausibility, and characteristics, of these events. Molten Fuel Stream Breakup Simulation (MFSBS) experiments have been performed at Argonne National Laboratory in which simulant materials were used to determine a `boiling` jet breakup length correlation and to visualize the melt fragmentation mechanisms during the penetration of a single molten metal jet into a volatile liquid. The goal was to characterize the hydrodynamics of the corium-water interactions in a postulated core melt accident. The present experiment closely follows the procedures of the MFSBS.
Date: July 1, 1995
Creator: Marciniak, M.J.
Partner: UNT Libraries Government Documents Department

Baryon stopping and charged particle production from lead-lead collisions at 158 GeV per nucleon

Description: Net proton (proton minus antiproton) and negative charge hadron spectra (h-) from central Pb+Pb collisions at 158 GeV per nucleon at the CERN Super Proton Synchrotron were measured and compared to spectra from central collisions of the lighter S+S system. Net baryon distributions were derived from those of net protons and net lambdas. Stopping, or rapidity shift with respect to the beam, of net protons and net baryons increase with system size. The mean transverse momentum &60;pT&62; of net protons also increase with system size. The h- rapidity density scales with the number of participant nucleons for nuclear collisions, where their &60;pT&62; is independent of system size. The &60;pT&62; dependence upon particle mass and system size is consistent with larger transverse flow velocity at midrapidity for central collisions of Pb+Pb compared to that of S+S.
Date: July 1, 1999
Creator: Toy, Milton Y.
Partner: UNT Libraries Government Documents Department

Solidification/Stabilization of High Nitrate and Biodenitrified Heavy Metal Sludges with a Portland Cement/Flyash System

Description: Pond 207C at Rocky Flats Environmental Technology Site (RFETS) contains process wastewaters characterized by high levels of nitrates and other salts, heavy metal contamination, and low level alpha activity. The purpose of this research was to investigate the feasibility of treating a high-nitrate waste, contaminated with heavy metals, with a coupled dewateriug and S/S process, as well as to investigate the effects of biodenitrification pretreatment on the S/S process. Pond 207C residuals served as the target waste. A bench-scale treatability study was conducted to demonstrate an S/S process that would minimize final product volume without a significant decrease in contaminant stabilization or loss of desirable physical characteristics. The process formulation recommended as a result a previous S/S treatability study conducted on Pond 207C residuals was used as the baseline formulation for this research. Because the actual waste was unavailable due to difficulties associated with radioactive waste handling and storage, a surrogate waste, of known composition and representative of Pond 207C residuals, was used throughout this research. The contaminants of regulatory concern added to the surrogate were cadmium, chromium, nickel, and silver. Product volume reduction was achieved by dewatering the waste prior to S/S treatment. The surrogate was dewatered by evaporation at 60 to 80 C to total solids contents from 43% to 78% by weight, and treated with Portland cement and fly ash. Two cement to flyash ratios were tested, 2:1 and 1:2, by weight. Contaminant leachability testing was conducted with a 0.5 water to pozzolan (the cement/flyash mixture) ratio and both cement to flyash ratios. Each product was tested for unconfined compressive strength (UCS) and for contaminant leachability by the Toxicity Characteristics Leaching Procedure (TCLP). At the highest solids content achieved by dewatering, 78% solids by weight, the predicted final waste form volume f or Pond 207C residuals after ...
Date: July 26, 1995
Creator: Canonico, J.S.
Partner: UNT Libraries Government Documents Department

Planning a Sound High School Testing Program

Description: A major consideration in this study has been given to the establishment of the criteria by which the soundness of a testing program could be evaluated as its role in the secondary school. This problem was limited to the planning and administering of a progressive and comprehensive long-range testing program designed to meet the needs and problems common to most school administrators within the economic limits of a small high school. It was not the purpose of this study to anticipate the problems peculiar to particular teachers, high schools, or localities. However, the testing program if properly directed will result in the formation of subsidiary testing programs undertaken by particular teachers or groups of teachers for the purpose of throwing light on the specific problems raised by a large general testing program.
Date: July 1948
Creator: Campbell, Claude W.
Partner: UNT Libraries

A Study of the Participation and Interests in Leisure Time Activities of the Women of Dallas, Texas

Description: "It is the purpose of this investigation to discover and report how the women of Dallas, Texas, spend their time when not engaged in their daily occupation. ... it attempts to disclose the trend of interest of various groups according to age, salary, and occupation; the influence of previous training; the reasons for non-participation in the activities in which they desire to take part. It is a further purpose to formulate various plans which are to evaluate academically or non-academically the activities that should be included in the program for the modern girl in the secondary school."-- leaf 1.
Date: July 1937
Creator: Wade, Irma E.
Partner: UNT Libraries

A Study of Ravel's Tombeau de Couperin

Description: Ravel' s "Tombeau de Couperin," a suite for piano, was published in 1918 by Durand. Its first performance was in the Salle Gaveau in Paris in April, 1919. Shortly afterwards Ravel scored four of the six movements of the piano suite for small orchestra, composed of flutes, oboes, clarinets, bassoons, and horns in pairs, English horn, trumpet, harp, and strings, The new version was introduced in America in 1920. The four orchestrated movements, Prelude, Forlane, Menuet, and Rigaudon, have no programmatic content and the titles identify the forms used. "Le Tombeau de Couperin" is a souvenir of World War I. Each movement is dedicated to the memory of a French soldier fallen in battle. The "Tombeau" form dates from the seventeenth century and is a musical "homage" to Francois Couperin, clavecinist of Louis XIV, and one of the great names of French music. "The separate movements, cast in eighteenth century dance forms often used by Qouperin have been described as "tonal wreaths," not too somber nor too profuse, laid with tenderness on an unforgotten tomb." This piece represents Ravel's extreme effort to express himself in the simplest possible manner. The music is subtly archaic; form, line and texture artfully suggest eighteenth century, but the harmony suggests twentieth century. "A transparent serenity full of color and feeling pervades this piece of classic purity written in tribute to Ravel's fallen comrades." A study of the piano suite has been made. The pieces are charmingly and precisely orchestrated. They have been used for a ballet which will not be dealt with.
Date: July 1947
Creator: Henderson, Ruth
Partner: UNT Libraries

Measurement of Z{sup 0} lepton coupling asymmetries

Description: Polarized Z{sup 0}`s from e{sup +}e{sup {minus}} collisions at the SLAC Linear Collider (SLC) have been used to determine the asymmetry parameters A{sub e}, A{sub {mu}} and A{sub {tau}} from the leptonic decay channels. This is the first direct measurement of A{sub {mu}}. The data have been gathered by the SLC Large Detector (SLD) with the electron polarization averaging 63% during the 1993 data taking period and 77% in 1994-95. A maximum likelihood procedure as well as cross section asymmetries was used to measure the asymmetry parameters from the differential cross sections for equal luminosities of left- and right-handed electron beams. The polarization-dependent muon-pair distributions give A{sub {mu}} = 0.102 {+-}0.034 and the tau-pairs give A{sub {tau}} = 0.195 {+-}0.034. The initial state electronic couplings in all three leptonic channels as well as the final state angular distribution in the e{sup +}e{sup {minus}} final state measure A{sub e} to be A{sub e} = 0.152{+-}0.012. Assuming lepton universality and defining a global leptonic asymmetry parameter A{sub e-{mu}-{tau}} = 0.151{+-}0.011. This global leptonic asymmetry value translates directly into sin{sup 2}{theta}{sub W}{sup eff}=0.2310{+-}0.0014 at the Z{sup 0} pole.
Date: July 1, 1997
Creator: Smy, M.B.
Partner: UNT Libraries Government Documents Department

Synthesis, characterization and application of electrode materials

Description: It has been known that significant advances in electrochemistry really depend on improvements in the sensitivity, selectivity, convenience, and/or economy of working electrodes, especially through the development of new working electrode materials. The advancement of solid state chemistry and materials science makes it possible to provide the materials which may be required as satisfactory electrode materials. The combination of solid state techniques with electrochemistry expands the applications of solid state materials and leads to the improvement of electrocatalysis. The study of Ru-Ti{sub 4}O{sub 7} and Pt-Ti{sub 4}O{sub 7} microelectrode arrays as introduced in paper 1 and paper 4, respectively, focuses on their synthesis and characterization. The synthesis is described by high temperature techniques for Ru or Pt microelectrode arrays within a conductive Ti{sub 4}O{sub 7} ceramic matrix. The characterization is based on the data obtained by x-ray diffractometry, scanning electron microscopy, voltammetry and amperometry. These microelectrode arrays show significant enhancement in current densities in comparison to solid Ru and Pt electrodes. Electrocatalysis at pyrochlore oxide Bi{sub 2}Ru{sub 2}O{sub 7.3} and Bi{sub 2}Ir{sub 2}O{sub 7} electrodes are described in paper 2 and paper 3, respectively. Details are reported for the synthesis and characterization of composite Bi{sub 2}Ru{sub 2}O{sub 7.3} electrodes. Voltammetric data are examined for evidence that oxidation can occur with transfer of oxygen to the oxidation products in the potential region corresponding to anodic discharge of H{sub 2}O with simultaneous evolution of O{sub 2}. Paper 3 includes electrocatalytic activities of composite Bi{sub 2}Ir{sub 2}O{sub 7} disk electrodes for the oxidation of I{sup -} and the reduction of IO{sub 3}{sup -}.
Date: July 7, 1995
Creator: He, L.
Partner: UNT Libraries Government Documents Department

Bis(pentamethylcyclopentadienyl)ytterbium: An investigation of weak interactions in solution using multinuclear NMR spectroscopy

Description: NMR spectroscopy is ideal for studying weak interactions (formation enthalpy {le}20 kcal/mol) in solution. The metallocene bis(pentamethylcyclopentadienyl)ytterbium, Cp*{sub 2}Yb, is ideal for this purpose. cis-P{sub 2}PtH{sub 2}complexes (P = phosphine) were used to produce slow-exchange Cp*{sub 2}YbL adducts for NMR study. Reversible formation of (P{sub 2}PtH){sub 2} complexes from cis-P{sub 2}PtH{sub 2} complexes were also studied, followed by interactions of Cp*{sub 2}Yb with phosphines, R{sub 3}PX complexes. A NMR study was done on the interactions of Cp*{sub 2}Yb with H{sub 2}, CH{sub 4}, Xe, CO, silanes, stannanes, C{sub 6}H{sub 6}, and toluene.
Date: July 1, 1995
Creator: Schwartz, D.J.
Partner: UNT Libraries Government Documents Department

RHEED studies of the nucleation, growth, and mobility of Ag atoms on the Si(111)7 x 7 surface

Description: The low temperature and flux dependent growth of ultrathin Ag films on the Si(111)7x7 surface is studied with Reflection High-Energy Electron Diffraction (RHEED). The grazing incidence geometry of RHEED allows for an incident molecular beam normal to the surface, and makes it an ideal surface probe for studying ultrathin film growth in real time. Short-lived oscillations in the diffracted intensity are observed during Ag deposition at 150 K, indicating quasi-layer-by-layer growth mediated by adatom mobility. When the 150 K growth is performed over a wide range of deposition rates F, the peak intensity is observed to scale, i.e. I(Ft) depends only on the total amount deposited, which implies thermally activated diffusion is absent at 150 K. Scaling is not obeyed at higher temperatures (T{ge}473 K) for the growth of the {radical}3{times}{radical}3 R30{degrees} ({radical}3) superstructure. Testing for scaling of the diffracted intensity constitutes a new experimental method which can be applied generally to determine if thermal diffusion is active at a particular temperature. Scaling is consistent with a constant diffusion length R{sub 0}, independent of substrate temperature and deposition rate. The presence of a non-thermal diffusion mechanism (responsible for the constant diffusion length R{sub 0}) is confirmed by monitoring the flux dependence of the {radical}3 superstructure growth during deposition at T{ge}473 K. At these temperatures the total diffusion length R is given by R=R{sub 0}+(4Dt){sup 1/2}, where (4Dt){sup 1/2} is the thermal component. A non-zero intercept R{sub 0} is found by plotting the peak intensity I{sub p}{sup 1/2} (a measure of the average domain size) vs. deposition rate F{sup {minus}1/2} (F{sup {minus}1} is proportional to the available diffusion time.) From the FWHM of a low coverage (0.2 ML) {radical}3 spot, an estimation of 50 {angstrom} is made for a lower bound of the magnitude of R{sub 0}.
Date: July 1, 1993
Creator: Roos, K.R.
Partner: UNT Libraries Government Documents Department

Development and Implementation of Photonuclear Cross-Section Data for Mutually Coupled Neutron-Photon Transport Calculations in the Monte Carlo N-Particle (MCNP) Radiation Transport Code

Description: The fundamental motivation for the research presented in this dissertation was the need to development a more accurate prediction method for characterization of mixed radiation fields around medical electron accelerators (MEAs). Specifically, a model is developed for simulation of neutron and other particle production from photonuclear reactions and incorporated in the Monte Carlo N-Particle (MCNP) radiation transport code. This extension of the capability within the MCNP code provides for the more accurate assessment of the mixed radiation fields. The Nuclear Theory and Applications group of the Los Alamos National Laboratory has recently provided first-of-a-kind evaluated photonuclear data for a select group of isotopes. These data provide the reaction probabilities as functions of incident photon energy with angular and energy distribution information for all reaction products. The availability of these data is the cornerstone of the new methodology for state-of-the-art mutually coupled photon-neutron transport simulations. The dissertation includes details of the model development and implementation necessary to use the new photonuclear data within MCNP simulations. A new data format has been developed to include tabular photonuclear data. Data are processed from the Evaluated Nuclear Data Format (ENDF) to the new class ''u'' A Compact ENDF (ACE) format using a standalone processing code. MCNP modifications have been completed to enable Monte Carlo sampling of photonuclear reactions. Note that both neutron and gamma production are included in the present model. The new capability has been subjected to extensive verification and validation (V&V) testing. Verification testing has established the expected basic functionality. Two validation projects were undertaken. First, comparisons were made to benchmark data from literature. These calculations demonstrate the accuracy of the new data and transport routines to better than 25 percent. Second, the ability to calculate radiation dose due to the neutron environment around a MEA is shown. An uncertainty of a ...
Date: July 1, 2000
Creator: White, Morgan C.
Partner: UNT Libraries Government Documents Department

Tunable coherent radiation at soft X-ray wavelengths: Generation and interferometric applications

Description: The availability of high power, spectrally and spatially coherent soft x-rays (SXR) would facilitate a wide variety of experiments as this energy region covers the primary resonances of many magnetic and biological materials. Specifically, there are the carbon and oxygen K-edges that are critical for biological imaging in the water window and the L-edges of iron, nickel, and cobalt for which imaging and scattering studies can be performed. A new coherent soft X-ray branchline at the Advanced Light Source has begun operation (beamline 12.0.2). Using the third harmonic from an 8 cm period undulator, this branch delivers coherent soft x-rays with photon energies ranging from 200eV to 1keV. This branchline is composed of two sub-branches one at 14X demagnification and the other 8X demagnification. The former is optimized for use at 500eV and the latter at 800eV. Here the expected power from the third harmonic of this undulator and the beamline design and characterization is presented. The characterization includes measurements on available photon flux as well as a series of double pinhole experiments to determine the coherence factor with respect to transverse distance. The first high quality Airy patterns at SXR wavelengths are created with this new beamline. The operation of this new beamline allows for interferometry to be performed in the SXR region. Here an interferometric experiment designed to directly determine the index of refraction of a material under test is performed. Measurements are first made in the EUV region using an established beamline (beamline12.0.1) to measure silicon, ruthenium and tantalum silicon nitride. This work is then extended to the SXR region using beamline 12.0.2 to test chromium and vanadium.
Date: July 1, 2004
Creator: Rosfjord, Kristine Marie
Partner: UNT Libraries Government Documents Department