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Projectile-Charge Dependence Of Ejected-Electron Spectra, V. D. Irby, Timothy James Gay, Jimmie Garwin Edwards, Edward Boyd Hale, M. L. Mckenzie, Ronald E. Olson Jan 1988

Projectile-Charge Dependence Of Ejected-Electron Spectra, V. D. Irby, Timothy James Gay, Jimmie Garwin Edwards, Edward Boyd Hale, M. L. Mckenzie, Ronald E. Olson

Physics Faculty Research & Creative Works

We have studied H++He and He++3+He ionizing collisions at intermediate energies (60 to 120 keV/amu) and have observed a significant shift in the velocity position of the maxima in forward-ejected electron spectra when changing projectiles from protons to particles. In ionizing collisions, a large portion of the ejected electrons are stranded near the transitory equiforce, or saddle point, position between the target ion and receding projectile. The shift in the electron spectra maxima to smaller velocities, due to changing projectiles from protons to particles, is consistent with the shift in the saddle-point velocity when the projectile …

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Radiobiological Modeling Based On Track Structure, Robert Katz Jan 1988

Radiobiological Modeling Based On Track Structure, Robert Katz

Robert Katz Publications

Since the interaction of beams of charged particles with targets in physics is customarily based on beam fluence and interaction cross section we have chosen the same logical structure for our radiobiological model.

Proceeding from simple to complex systems we have first constructed and verified a track structure model of observable tracks in nuclear emulsions, then of dry enzymes and viruses, of scintillation counters, of TLD’s, of the Fricke dosimeter as prerequisite to the construction of a valid radiobiological model.

For this model we require 1) knowledge of the average radial distribution of local dose about the path of an …

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Molecular-Dynamics Simulation Of The Structural Phase Transition In Rb2Cacl4, D. P. Billesbach, P. J. Edwardson, John R. Hardy Jan 1988

Molecular-Dynamics Simulation Of The Structural Phase Transition In Rb2Cacl4, D. P. Billesbach, P. J. Edwardson, John R. Hardy

John R. Hardy Papers

We have simulated the structural phase transition of one member of A2BX4 layered perovskite-like compounds, Rb2CaC14. This family of compounds may be thought of as being constructed from normal perovskite unit cells but with a different stacking arrangement. In recent months, this structural family has become extremely important since it is the parent structure from which the new class of high-temperature superconductors comes from. The simulation was done using ab initio potentials with no adjustable parameters. Our calculations show a specific-heat anomaly at 400 K which corresponds to an observed pseudorotation of the …

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Bacterial Biomagnetism And Geomagnetic Field Detection By Organisms, Richard P. Blakemore, Nancy A. Blakemore, Richard B. Frankel Jan 1988

Bacterial Biomagnetism And Geomagnetic Field Detection By Organisms, Richard P. Blakemore, Nancy A. Blakemore, Richard B. Frankel

Physics

No abstract provided.

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The Energy-Dependence Of Polarization Observables In The ²H(D,Γ)⁴He Reaction, H. R. Weller, R. M. Whitton, J. Langenbrunner, Evans Hayward, W. R. Dodge, S. Kuhn, D. R. Tilley Jan 1988

The Energy-Dependence Of Polarization Observables In The ²H(D,Γ)⁴He Reaction, H. R. Weller, R. M. Whitton, J. Langenbrunner, Evans Hayward, W. R. Dodge, S. Kuhn, D. R. Tilley

Physics Faculty Publications

Measurements of the tensor and vector analyzing powers, Ayy(130°) and Ay(130°), have been obtained for the 2H(d,γ )4He reaction for energies ranging from Ed(lab) = 0.3 MeV to Ed(lab) = 50 MeV. The Ayy(130°) data are sensitive to the D-state present in the ground state of 4He and are observed to have their maximum value near Ed = 30 MeV. The vector analyzing power data show a maximum near Ed = 3 MeV. The data are compared to the results of a microscopic …

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Preparation, Crystal Structure, And Physical Properties Of A Pyrogallol-Bridged Vanadium(Iii) Complex, Seunghee Lee, Koji Nakanishi, Michael Y. Chiang, Richard B. Frankel, K. Spartalian Jan 1988

Preparation, Crystal Structure, And Physical Properties Of A Pyrogallol-Bridged Vanadium(Iii) Complex, Seunghee Lee, Koji Nakanishi, Michael Y. Chiang, Richard B. Frankel, K. Spartalian

Physics

The structure, n.m.r. spectrum, and magnetic properties of the vanadium(III) dimer [(acac)4V2{µ-OC6H3(OH)2}2] formed from [VO(acac)2] and an excess of pyrogallol are described.

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Nonlocal Symmetries And Backlund Transformations For The Self-Dual Yang-Mills System, C. J. Papachristou, Kent B. Harrison Jan 1988

Nonlocal Symmetries And Backlund Transformations For The Self-Dual Yang-Mills System, C. J. Papachristou, Kent B. Harrison

Faculty Publications

The observation is made that generalized evolutionary isovectors of the self-dual Yang–Mills equation, obtained by "verticalization'' of the geometrical isovectors derived in a previous paper [J. Math. Phys. 28, 1261 (1987)], generate Bäcklund transformations for the self-dual system. In particular, new Bäcklund transformations are obtained by "verticalizing'' the generators of point transformations on the solution manifold. A geometric ansatz for the derivation of such (generally nonlocal) symmetries is proposed.

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Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele Jan 1988

Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele

Faculty Publications

Using a formulation of quantum electrodynamics that is not second quantized, but rather based on self-fields, we compute the anomalous magnetic moment of the electron to first order in the fine structure constant α. In the nonrelativistic (NR) case and in the dipole approximation, our result is ae≡(g—2)/2=(4Λ/3m)(α/2π), where Λ is a positive photon energy cutoff and m the electron mass. A reasonable choice of cutoff, Λ/m=¾, yields the correct sign and magnitude for g—2 namely, ae=+α/2π. . In our formulation the sign of a3 is correctly positive, …

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Comparison Of Effective Medium Procedures For Optical Modeling Of Laminar Structures, David D. Allred, Robert F. Edgerton Jan 1988

Comparison Of Effective Medium Procedures For Optical Modeling Of Laminar Structures, David D. Allred, Robert F. Edgerton

Faculty Publications

This study addresses the question, "How can the optical properties of matter in ultrathin amorphous nonmetallic films in multilayers best be determined from reflectance (R) and transmission (T) measurements?" A blue shift in the band gap of plasma CVD a-Si:H/a-SiNx:H multilayers was reported several years ago. It was suggested that the shift in the band gap, Eg, Relative to bulk a-Si:H as given by the Tauç plot was due to quantum confinement effects. The purpose of this study is to evaluate the usefulness of various effective media theories (EMT) for determining the optical constants of materials in a multilayer and …

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The Effectiveness Of Using Writing In The High School Biology Classroom, Lynne E. Kelly Jan 1988

The Effectiveness Of Using Writing In The High School Biology Classroom, Lynne E. Kelly

Dissertations and Theses @ UNI

"Writing across the curriculum" programs have emerged throughout the United States during the last decade as an attempt to improve both writing skills and learning of today's youth. The purpose of this study was to determine if students learn and retain concepts of biology to a greater extent in a program using expressive writing than a program using traditional expository writing. The sample consisted of two high school biology classes from Fort Dodge Senior High School, Fort Dodge, Iowa. Expressive writing assignments were incorporated into the biology curriculum of the experimental group two to four times a week during the …

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Condensation Method For Humidity Measurement In The Umr Cloud Simulation Chamber., Donald E. Hagen, Daniel R. White, Darryl J. Alofs Jan 1988

Condensation Method For Humidity Measurement In The Umr Cloud Simulation Chamber., Donald E. Hagen, Daniel R. White, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A Cloud Simulation Facility Has Been Developed for the Study of Various Atmospheric Cloud Processes. the Initial Relative Humidity of the Air Sample Put into the Cloud Chamber is a Key Parameter in Virtually Any Experiment and Needs to Be Known Accurately. This Report Describes How the Cloud Simulation Chamber itself Has Been Used as a Condensation Type Hygrometer to Calibrate the System's Humidifier. Two Distinct and Physically Different Methods for Inferring Mixing Ratio Are Used, One Exploiting the Sensitivity of Aerosol Activation to Humidity, and the Other Exploiting the Sensitivity of the Rate of Growth of Cloud Droplets to …

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Charge- And Angle-Correlated Inelasticities In Collisions Of Bare Fast Carbon Ions With Neon, R. Schuch, H. Schöne, P. D. Miller, H. F. Krause, P. F. Dittner, S. Datz, Ronald E. Olson Jan 1988

Charge- And Angle-Correlated Inelasticities In Collisions Of Bare Fast Carbon Ions With Neon, R. Schuch, H. Schöne, P. D. Miller, H. F. Krause, P. F. Dittner, S. Datz, Ronald E. Olson

Physics Faculty Research & Creative Works

We have studied the detailed energy balance in collisions of 10-MeV C6+ ions with Ne. In these collisions, the Ne is multiply ionized and the C ion may emerge as either C6+ or C5+. Projectile energy loss and scattering angle for a given carbon-ion charge state were determined in a high-resolution magnetic spectrograph and were measured in coincidence with the formation of a given Ne recoil-ion charge state. The amount of energy transferred to the continuum electrons exceeds, by far, the sum of the values of the ionization potentials. © 1988 The American Physical Society.

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Dynamics Of Antimatter-Atom Collisions, Ronald E. Olson, Timothy James Gay Jan 1988

Dynamics Of Antimatter-Atom Collisions, Ronald E. Olson, Timothy James Gay

Physics Faculty Research & Creative Works

Classical-trajectory Monte Carlo calculations have been used to study ionizing collisions between charged particles (p,p»,e+,e-) and He atoms at an incident velocity of 2.83 a.u. While differences in the total single-ionization cross sections for these projectiles are small, our calculations reveal large effects at all angles in the ionized electron spectra and provide qualitative evidence for a Barkas effect in p and p» collisions. Experimental data agree well with our fully classical calculations, including cross sections involving ejected electrons of long wavelength. © 1988 The American Physical Society.

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Electron Loss From Helium Atoms By Collisions With Fully Stripped Ions, A. E. Wetmore, Ronald E. Olson Jan 1988

Electron Loss From Helium Atoms By Collisions With Fully Stripped Ions, A. E. Wetmore, Ronald E. Olson

Physics Faculty Research & Creative Works

Electron-loss cross sections have been calculated for fully stripped ions with charge states +1 to +100 colliding with helium atoms in the energy range 100 1000 kev/amu. The classical-trajectory Monte Carlo method was used along with a model of the helium atom with two active electrons. The reactions studied were single and double ionization, single- and double-electron capture, and electron capture plus ionization. Cross sections for the single-electron-removal reactions agree well with experimental data. Double-electron-removal cross sections are in qualitative agreement with experimental results. The n-level distributions following electron capture show that the electron-capture plus ionization and double electron-capture processes …

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Contribution Of Excited Hydrogen Atoms To Charge-Exchange Excitation Of Impurities In Fusion Plasmas, R. C. Isler, Ronald E. Olson Jan 1988

Contribution Of Excited Hydrogen Atoms To Charge-Exchange Excitation Of Impurities In Fusion Plasmas, R. C. Isler, Ronald E. Olson

Physics Faculty Research & Creative Works

Cross sections are calculated for charge transfer into excited states of C5+ and O7+ from collisions of C6+ and O8+ with hydrogen atoms in the n=2 and 3 levels. Effective emission cross sections that account for cascading is then derived for spectral lines emitted when the product ions decay. These are compared to the emission cross sections calculated for excitation by ground-state hydrogen. It is shown that in some circumstances the contribution from excited hydrogen atoms must be taken into account when visible lines are used to determine the oxygen or carbon density from charge-exchange spectroscopy …

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Single-Electron Removal Processes In Collisions Of Positrons And Protons With Helium At Intermediate Velocities, D. R. Schultz, Ronald E. Olson Jan 1988

Single-Electron Removal Processes In Collisions Of Positrons And Protons With Helium At Intermediate Velocities, D. R. Schultz, Ronald E. Olson

Physics Faculty Research & Creative Works

Total cross sections for single ionization and charge transfer have been calculated using the classical-trajectory Monte Carlo (CTMC) technique for collisions of both positrons and protons with helium. Analysis of the classical trajectories has helped to explain the differences in the collision mechanisms responsible for the observed relative magnitudes of the positron and proton electron-removal cross sections. In the intermediate collision velocity range (1.5 a.u.

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Discharge Suppression System For A Double Focusing, Atmospheric Pressure Ionization Mass Spectrometer, Andrew H. Grange, Robert J. O'Brien, Douglas F. Barofsky Jan 1988

Discharge Suppression System For A Double Focusing, Atmospheric Pressure Ionization Mass Spectrometer, Andrew H. Grange, Robert J. O'Brien, Douglas F. Barofsky

Chemistry Faculty Publications and Presentations

An electrical discharge suppression system for a medium throughput (∼2 l/s) pumping line has been devised that works up to potentials of ±15 kV. This device permits atmospheric pressure ionization sources to be interfaced to high-resolution, magnetic sector mass spectrometers with source potentials of 6-10 kV

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State-Selective Studies Of T→R, V Energy Transfer: The H+Co System, G. K. Chawla, George C. Mcbane, P. L. Houston, G. C. Schatz Dec 1987

State-Selective Studies Of T→R, V Energy Transfer: The H+Co System, G. K. Chawla, George C. Mcbane, P. L. Houston, G. C. Schatz

Peer Reviewed Articles

Collisional energy transfer from H atoms to CO(v=0, J≈2) has been studied at a collision energy of 1.58±0.07 eV by photolyzing H2S at 222 nm in a nozzle expansion with CO and probing the CO(v", J") levels using tunable VUV laser-induced fluorescence. The ratio CO(v"=1)/CO(v"=0) is found to be 0.1±0.008. The rotational distribution of CO(v"=0) peaks at J"gradually; population is still observed at J">45. The rotational distribution of CO(v"=1) is broad and peaks near J"=20. The experimental results are compared to …

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Theory Of The Observations Made Of High-Order Rainbows From A Single Water Droplet, James A. Lock Dec 1987

Theory Of The Observations Made Of High-Order Rainbows From A Single Water Droplet, James A. Lock

Physics Faculty Publications

Over a dozen rainbows have been observed in a single water droplet. They appear as glare spots on the water droplet which take on coloration at the appropriate rainbow angles. The appearance of rainbows as colored glare spots in this situation is understood in terms of the caustics created in the vicinity of the droplet by the refracting light rays. The angular positions of the glare spots are understood in terms of the Fourier transform of the geometric scattering amplitude. The rainbow glare spots are also found to appear numerically in the Fourier transform of the Mie scattered fields. An …

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Evidence For Weak Link And Anisotropy Limitations On The Transport Critical Current In Bulk Polycrystalline Y1Ba2Cu3O Χ , J.W. Ekin, A.I. Braginski, A.J. Panson, M.A. Janocko, D.W. Capone Ii, N.J. Zaluzec, B. Flandermeyer, O.F. De Lima, M. Hong, J. Kwo, Sy_Hwang Liou Dec 1987

Evidence For Weak Link And Anisotropy Limitations On The Transport Critical Current In Bulk Polycrystalline Y1Ba2Cu3O Χ , J.W. Ekin, A.I. Braginski, A.J. Panson, M.A. Janocko, D.W. Capone Ii, N.J. Zaluzec, B. Flandermeyer, O.F. De Lima, M. Hong, J. Kwo, Sy_Hwang Liou

Sy-Hwang Liou Publications

Measurements of the transport critical-current density (Jc), magnetization Jc, and magnetoresistance in a number of bulk sintered samples of Y1Ba2Cu3O χ from several different laboratories indicate that the transport Jc is limited by weak-link regions between high Jc regions. The weak-link Jc has a Josephson character, decreasing by two orders of magnitude as the magnetic field is increased from 0.1 to 10 mT at 77 K. An examination of the grain-boundary region in Y1Ba2Cu3O χ shows no observable impurities or …

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Generating Problem Sets With Word Processing Software, Jearl D. Walker Dec 1987

Generating Problem Sets With Word Processing Software, Jearl D. Walker

Physics Faculty Publications

No abstract provided.

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The O-O Collision Cross-Section: Can It Be Inferred From Aeronomical Measurements?, R G. Burnside, C A. Tipley, Vincent B. Wickwar Dec 1987

The O-O Collision Cross-Section: Can It Be Inferred From Aeronomical Measurements?, R G. Burnside, C A. Tipley, Vincent B. Wickwar

All Physics Faculty Publications

No abstract provided.

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Electrooptic And Piezoelectric Measurements In Photorefractive Barium Titanate And Strontium Barium Niobate, Stephen Ducharme, Jack Feinberg, R.R. Neurgaonkar Dec 1987

Electrooptic And Piezoelectric Measurements In Photorefractive Barium Titanate And Strontium Barium Niobate, Stephen Ducharme, Jack Feinberg, R.R. Neurgaonkar

Stephen Ducharme Publications

We have measured the low-frequency ("unclamped") electrooptic and piezoelectric coefficients in undoped BaTiO3and SrxBa1-xNb2O6 (x = 0.61) crystals using interferometric techniques. The contribution of the piezoelectric effect to the Pockels measurements is discussed. For an applied ac electric field in the range 0.1-200 V/cm, the electrooptic and piezoelectric effects are linear in the magnitude of the applied field and independent of its frequency in the range 10 Hz-100 kHz. The unclamped electrooptic coefficients of poled BaTiO3 single crystals are r13= 19.5 pm ±1 pm/V and r33 = …

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Moment Analysis Of The Cluster-Size-Distribution Approach To Scaling During Coagulation, Thomas W. Taylor, C. M. Sorensen Dec 1987

Moment Analysis Of The Cluster-Size-Distribution Approach To Scaling During Coagulation, Thomas W. Taylor, C. M. Sorensen

Physics Faculty Publications

We study the temporal approach of a cluster size distribution to its asymptotic scaling form. By enforcing consistency between the distribution’s zeroth moment derived from both the Smoluchowski equation and the scaling distribution ansatz, we find values for the scaling exponents w and z in terms of the scaling exponent τ and the kernel homogeneity λ which are not equivalent to their asymptotic, scaling forms. The predicted values do agree well, however, with intermediate time values found in simulations by Kang, Redner, Meakin, and Leyvraz [Phys Rev. A 33, 1171 (1986)]. By enforcing consistency between all moment orders, the asymptotic …

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Numerical Methods In Optics: A Course About Learning Physics Through Computing, James A. Lock Dec 1987

Numerical Methods In Optics: A Course About Learning Physics Through Computing, James A. Lock

Physics Faculty Publications

Many advanced undergraduates find it difficult to connect abstract mathematical formalisms with the concrete physical phenomena that they describe. A course in optics from a numerical methods point of view is described. Its purpose is to exploit the students’ familiarity with computng in order to more effectively learn the physics involved in a number of realistic phenomena. The combination of demonstrations, computer calculations, and computer graphics display of the results can prove to be a useful tool in developing physical intuition in students.

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Ion-Ion Recombination In Mixtures Of Methane And Sulphur Hexafluoride, M. C. Cornell, Ian M. Littlewood Dec 1987

Ion-Ion Recombination In Mixtures Of Methane And Sulphur Hexafluoride, M. C. Cornell, Ian M. Littlewood

Physics Faculty Research & Creative Works

The authors have measured the recombination rate for positive and negative ions in Sulphur hexafluoride and in mixtures of methane and Sulphur hexafluoride in an electron beam sustained discharge. Measurements were made as a function of gas composition, gas pressure in the range 100 to 600 Torr, and reduced electric field strength in the range 12 to 150 Td. When plotted as a function of an effective ion temperature, defined by the drift velocities of the ions in the applied electric field, the rates in each of the gas mixtures follow the same Teff-1.6 power law. From comparisons with theories …

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Thermodynamics Of The Diluted Spin Heisenberg Chain With Single Ion Anisotropy, Salmah Ahmed Dec 1987

Thermodynamics Of The Diluted Spin Heisenberg Chain With Single Ion Anisotropy, Salmah Ahmed

Masters Theses

The thermodynamics of the one-dimensional diluted Heisenberg magnet of classical spins in the presence of single ion anisotropy is calculated. The magnetization, susceptibility, energy and specific heat are determined as functions of the magnetic concentration and single ion anisotropy for both ferromagnetic and antiferromagnetic couplings. Spin-spin correlation functions and the elastic scattering are also calculated for various values of anisotropy and spin concentration for the ferromagnetic system.

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Magnetically Induced Circular Polarization, K.L. Stricklett, D.J. Burns, Paul Burrow Dec 1987

Magnetically Induced Circular Polarization, K.L. Stricklett, D.J. Burns, Paul Burrow

Paul Burrow Publications

Helium atoms excited to an aligned (1s3d) 3D state are produced by electron impact parallel to a magnetic field. The initial alignment of the atomic state evolves into an orientation with finite angular momentum along the magnetic field direction and thus gives rise to a circularly polarized component in the (1s3d) 3D→(1s2p) 3P radiation propagating parallel to the magnetic field. Circular-polarization fractions of a few percent are observed, in general agreement with theory. The measured polarization fraction is found to be pressure dependent, indicating that secondary excitation and cascade processes must be included for a complete description.

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Hypernuclear Photoproduction Via (Γ,K*), Kimberly Ann Hodgkinson Dec 1987

Hypernuclear Photoproduction Via (Γ,K*), Kimberly Ann Hodgkinson

Masters Theses

The nuclear (γ,K*) reaction is studied using plane wave impulse approximation (PWIA) and a distorted wave impulse approximation (DWIA), which includes full Coulomb and optical distortions. The model and calculations for each model are presented. For 12C(γ K*)12B, the two approximation methods are compared at 2 energies: 1.47 Gev/c and 1.84GeV/c. 208Pb(γ, K*)208 i s a lso examined. Distortion effects are found to greatly alter the magnitude of the cross sections, but the shape of the angular distributions remains. the same. Conclusions suggest further study.

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Theoretical Thermodynamic Properties Of Low Temperature Fluids, Zul Azhar Zahid Jamal Dec 1987

Theoretical Thermodynamic Properties Of Low Temperature Fluids, Zul Azhar Zahid Jamal

Masters Theses

The thermodynamic functions for low temperature fluids are computed using parametric integral equations and perturbation theory. Parametric integral equation N is applied to a low temperature Lennard-Jones gas. It is found that there is no significant improvement over the better known parametric integral equation C. The two parameter integral equation T is applied to a low temperature square-well potential and is found to be unsatisfactory at reduced temperatures of T*= 1.4 and 1.6, but quite accurate at T* = 2.2. The equation T results for T* = 2.2 are used as the reference system in perturbation theory computations. Tables of …

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