Physical Sciences and Mathematics Commons^™

Magnetoresistance In Iron And Cobalt To 150 Koe , R.V. Coleman, R.C. Morris, David J. Sellmyer

David Sellmyer Publications

Magnetoresistance anisotropy and field dependence have been studied in single crystals of iron and cobalt in fields up to 150 kOe in the temperature range 1-4.2 K. The crystals of iron and cobalt had residual resistance ratios up to ∼4600 and ∼400, respectively. The relation Δρ/ρ₀=aBⁿ has been studied for both metals and in the case of iron the exponent n approaches values in the range 1.8-1.9 for fields up to 90 kOe and then decreases to the range 1.3-1.5 at 150 kOe. This decrease in the exponent has been observed for all field and current …

Proton-Scattering On (29)Si In Range Ep = 2.5-3.4 Mev*, Joseph W. Hemsky, S. C. Ling, Paul J. Wolfe

Physics Faculty Publications

Elastic and inelastic proton scattering measurements on Elastic and inelastic proton scattering measurements on ²⁹Si have been obtained in the energy range E_p = 2.5-3.4 MeV. 30 elastic and 32 inelastic resonances were observed. 14 prominent resonances from elastic scattering were analyzed. Results of the analysis for proton orbital momenta, spin and parity assignments, and proton partial widths are given. The inelastic resonance strengths measured relative to the known strength of the 1302-keV resonance in ²⁹Si(p,y)³⁰P are also reported.

Electron-Beam Retardation Contact Potential Of Cuprous Oxide, James Lindle

Masters Theses & Specialist Projects

The purpose of this research is to determine the contact potential of cuprous oxide, Cu₂O, with respect to gold. A band model for cuprous oxide is presented.

Single-crystal cuprous oxide is prepared from Oxygen Free High Conductivity copper equilibrated at 120°C and at atmospheric pressure. The contact potential difference of cuprous oxide (using gold as a reference) is measured in a bakeable ultrahigh vacuum system using a modified version of Nelson's electron beam retardation method. Measurements made at 10^-6 torr and at room temperature give a value of 0.1 +/-0.05 eV for the contact potential difference of …

Sensor Package For Electrical Sensing Of Plane Coordinates And Method Of Preparing The Same, George S. Hurst, William C. Colwell Jr.

Physics and Astronomy Faculty Patents

A sensor package for ready insertion in properly registered position upon, or for removal from, a cabinet employed in electrical sensing of plane coordinates, is constructed to provide accurate readings when pierced by a small manually operated cursor.

A method for manufacturing the package including the affixing of accurately spaced electrodes on the package, is disclosed.

Simulated Alpha Scattering, Gerald L. Fuller

Honors Theses

My approach to the experiment is to use a box of certain dimension as the Gold atom. This, I'm going to bombard with B.B's as alpha particles. Therefore this is a simulated alpha scattering experiment. The box is like unto the atom whereas shooting into it you cannot see what happens nor where it happens, but draw on your information taken while observe the effects outside the atom and the box likewise. A screen is used with the atom, and I have used a cardboard square placed in slats around my box to record the direction the particles enters and …

Dynamic Impulse Calibration Of Sheet Loaded Explosive, William James Johnson

Physics & Astronomy ETDs

In the past, experimenters have used Sheet Loaded Explosive (SLE) to simulate the damage caused by x-rays to an ICBM as the result of a nuclear burst from an ABM. One of the attractive features of SLE is that it can also provide high impul3e levels for structural damage studies. Previous measurements of the usual shock parameters such as peak overpressure, ietonation velocity, and shock front definition with short time interval pressure transducers were not suitable for total impulse measurements. The High Explosive Impulse Responder (HEIR) was developed to fill the need for a simple, reliable and economical total impulse …

A Relativistic One Pion Exchange Model Of Proton-Neutron Electron-Positron Pair Production, William A. Peterson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Proton-neutron electron-positron pair production cross sections are calculated in the framework of the pseudoscalar one-pion exchange model in a fully relativistic manner.

A computer program has been developed to evaluate invariants and Dirac traces for a given data point.

The sections for symmetric coplanar events for laboratory kinetic energies of 10 to 250 MeV were calculated for pair angles of 20° to 120°.

Frequency distributions were also calculated, at a laboratory energy of 200 MeV, using a random number generator to select data points. The frequency distributions are illustrated by curves.

It was noted that the inclusion of heavier bosons …

Quasi-Landau Spectrum Of A Hydrogen Like Atom In A High Magnetic Field, Anthony F. Starace

Anthony F. Starace Publications

A two dimensional semiclassical approximation is used to examine the σ polarization spectrum of a hydrogen like atom in a strong magnetic field. Resonances above the zero field ionization limit are found and their energy separations are computed over the region from the ionization limit to 40 ħω_c above, where ω_c is the cyclotron frequency, for magnetic fields of 10, 17, 25, 32, 40 and 47 kG. At the ionization limit the separation between resonances is found to be 1.500 ħω_c, independent of magnetic field strength, which is in agreement with a separation of 1.5 ħω …

Evaluation Of An Experiment In Computer -Assisted Tutoring, Stephen L. Cunningham, Robert Fuller

Robert G. Fuller Publications

It was made apparent from the presentations at the Conference of Computers in Undergraduate Science Education that very few Computer-Assisted Instructional (CAI) programs in physics attempt to evaluate the performance of computer- tutored students in comparison with a control group. In this note, we discuss an experiment in which 23 beginning physics students out of a class of 64 were given a computer-administered tutoring test in place of the regular review recitation session prior to an hour exam on relativity. The performance of the computer-tutored group on the exam was compared to the performance of the rest of the class.

Li-8 Magnetic Dipole-Moment, Richard C. Haskell, Leon Madansky

All HMC Faculty Publications and Research

Polarized 8Li nuclei recoiling from the reaction 7Li(d, p)8Li were implanted in Au, Pd, and Pt foils, and the Knight-shifted values of the 8Li magnetic dipole moment in these metals were measured by a resonant depolarization technique. From measurements of the spinlattice relaxation times of 8Li implanted in Au, Pd, and Pt, the Knight shifts of 8Li in these metals were estimated. A corrected value for the magnetic dipole moment of 8Li was found to be μ(8Li)=(1.653 35±0.000 35)μN. Attempts were also made to measure the quadrupole couplings of 8Li in single crystals of Be and Mg. While the resonance …

Effects Of Nuclear Deformation On Neutron Total Cross Sections, Dennis Gilbert Blondin

Masters Theses

No abstract provided.

Static Equilibrium Conditions For A Rigid-Ion Crystal, L. L. Boyer, John R. Hardy

John R. Hardy Papers

The equilibrium requirements for a static ionic crystal impose a number of constraints on the short-range forces which become increasingly more important when one is dealing with complex structures. These constraints are presented and discussed for a general rigid-ion lattice, and a specific discussion is presented for the wurtzite structure.

Projected Hartree Product Wavefunctions. Vi. Natural Orbital Ci Expansions In Nonsinglet Cases, R.D. Koller, Gordon A. Gallup

Gordon Gallup Publications

The NSO's and NO's have been determined for some wavefunctions for Li, Be¹⁺, B²⁺, C^{3+ 2}S, and Be ³S wavefunctions containing radial correlation. It is shown how the NO's may be utilized to form rapidly converging CI expansions in general. The role of the NSO's in this problem is discussed. ©1973 The American Institute of Physics

Determination Of The Origin Of The 10.6-Pm Absorption In C02 Laser Window Materials, John R. Hardy, B. S. Agrawal

John R. Hardy Papers

Theoretical studies are presented which show that it should be possible to determine whether the absorption at 10.6 pm in alkali halides is due to impurities or whether it is intrinsic. These studies show that the temperature dependence of the measured absorption should be very different for intrinsic multiphonon absorption as compared with defect-activated absorption.

Observation Of A Second-Order Phase Transition And Its Associated P - T Phase Diagram In Liquid He3, Richard A. Webb, T. J. Greytak, R. T. Johnson, J. C. Wheatley

Faculty Publications

A specific-heat "discontinuity" is observed in liquid He³ from 241 lb/in.2 to the melting pressure in the temperature range 2-3 mK.

Distorted-Wave Approximation And Its Application To The Differential And Integrated Cross Sections For Electron-Impact Excitation Of The 2¹P State Of Helium, Don H. Madison, W. Neil Shelton

Physics Faculty Research & Creative Works

Theoretical results are given for the application of the distorted-wave approximation to electron-atom impact excitation for transitions from an L-S coupled initial state to an arbitrarily coupled final state. Expressions for the differential cross section and spin polarization of the emitted electrons are given for unpolarized electron beams incident upon unpolarized atoms. These results are applied to excitation of helium from its ground state to the 1s2p¹P₁ excited state for incident-electron energies between 26.5 and 300 eV. The results are compared with previous theoretical and experimental works. It is found that the distorted-wave calculation is superior to …

Radiative And Predissociative Lifetimes Of The A ²Σ+ State Of Oh, Richard Orlin Sutherland, Richard A. Anderson

Chemistry Faculty Research & Creative Works

Lifetime measurements have been made on the A 2Σ+ state of OH by the delayed coincidence technique in conjunction with an interrupted rf discharge through water vapor. Lifetimes are reported for rotational states up to K=29 and K=20 in the ν=0 and ν=1 vibrational levels, respectively, and on the unresolved levels of ν=2. A predissociation, previously predicted from relative intensity measurements, resulting from a curve crossing by the repulsive 4Σ− state, was observed for the rotational states above K=23 of ν=0, for those above K=14 of ν=1, and for all those of ν=2. These lifetime data are discussed qualitatively in …

Spin Polarization And Differential Cross Section For Electron-Impact Excitation Of The 6s6p ¹P₁ State Of Mercury: Distorted-Wave Treatment, Don H. Madison, W. Neil Shelton

Physics Faculty Research & Creative Works

The results of the distorted-wave theory for electron-impact excitation of atoms are applied to the excitation of the 6s6p ¹P₁ state of mercury. The spin polarization and the differential cross section are given for unpolarized incident electron beams with energies between 25 and 180 eV. The distorted-wave results are compared with experimental data, and good agreement is found for both the spin polarization and differential cross section.

Absolute Line Strengths By Analysis Of Lu-Fano Plots With Application To Excited State Transitions In Neon, Anthony F. Starace

Anthony F. Starace Publications

Using energy eigenfunctions obtained by semi-empirical analysis of the Lu-Fano plot of energy level positions and employing the Coulomb approximation of Bates and Damgaard, we calculate absolute line strengths for transitions between the neon two-channel Rydberg series 2p⁵(²P_3/2,1/2)ns J = 1 and 2p⁵ (²P_3/2,1/2)n′ p J = 0 for n, n' = 3,4. Each Rydberg series is analyzed separately to obtain a set of five parameters which completely define the energy eigenfunctions for all values of n and n'. Interactions between the ns J = 1 …

Energies And Z-Expansion Coefficients For The D States In The Helium Sequence, P. Blanchard, Gordon W. F. Drake

Physics Publications

Non-relativistic variational energies for the 1s3d(1,3D) states of the helium isoelectronic sequence are calculated with a 50-term correlated basis set for Z=2-10, where Z is the nuclear charge, and the corresponding Z-expansion coefficients found through sixth order by fitting the energies to a series in Z-1. A variational-perturbation calculation of these coefficients through eleventh order (with the same basis set) is presented for comparison, and agreement is satisfactory. The 3d energies obtained by summing the Z-expansion perturbation series are found to yield excellent approximations to the variational values. The calculations are extended to the 1s4d( 1,3D) states to furnish variational …

Photon-Scattering Theory Of The Quenching Of Hydrogenic Metastables, Gordon W. F. Drake, R. B. Grimley

Physics Publications

The quenching of hydrogenic metastables is formulated as a near-resonant photon-scattering problem, and a complete analysis of the polarization and angular distribution of the emitted radiation is presented. The contribution from np states with n>2 is calculated, and an alternative method of measuring the Lamb shift is suggested. © 1973 The American Physical Society.

Antiferromagnetic To Paramagnetic Transition In Fe2+: Mnf2 In External Magnetic Fields, C. R. Abeledo, Richard B. Frankel, M. A. Weber, A. Misetich

Physics

Mössbauer effect measurements across the antiferromagnetic to paramagnetic phase boundary in Fe²⁺ : MnF₂ in external magnetic fields are reported. From the data, J(Mn-Fe)= -1.7 cm^-1. The phase boundary is found to vary as Ho2, as in pure MnF₂.

Far Infrared Absportion Of Fe(2+) In Kmgf3, R. B. Frankel, C. R. Abeledo, A. Misetich

Physics

Far infrared absorption in cubic KMgF₃ doped with Fe²⁺ is reported . A line is observed at 87cm−1, which is assigned to the (Γ5g → Γ3g, Γ4g) transition in the Fe²⁺. The reduction in the spin-orbit coupling from the free ion value has been predicted by Ham, Schwarz and O'Brien.

Neutron Scattering And The Dispersion Relation In He Ii At Small Momentum Transfer, Robert Hallock

Robert Hallock

Weighted-least-squares fits to the small momentum transfer (k≤1 Å-1) results of Woods and Cowley have been carried out. We find that the neutron data presently available (i) are not of sufficient accuracy to determine whether or not quadratic terms are present in the dispersion relation and (ii) weakly favor positive dispersion in the absence of the quadratic term.

Brief Theory Of Coherent Processor, Richard C. Heyser

Unpublished Writings

The particular coherent data processor which is to be discussed relies heavily upon several basic concepts. These concepts represent a departure from conventional practice and hence the theoretical description must await their presentation in order to gain some continuity. We will accordingly present the underlying assumptions and signal physics prior to description of the processor itself.

Ua77/1 Western Alumnus, Vol. 43, No. 2, Wku Alumni Association

WKU Archives Records

WKU alumni magazine. Features the following articles:

• Armstrong, Don. Engineering Technology Accredited
• Martin, Vernon & Don Armstrong. Public Affairs Aids Counties
• Distinguished Alumnus Julian Goodman
• Gray, David. WKU Physicist Invents Ultraviolet Dosimeter - William Buckman
• Richards, Jim. Why Recruit the Junior Colleges?
• Pageantry, Nostalgia & Victory - Homecoming
• Just, Paul. The Red and Gray Orchestra
• Ivan Wilson Center for Fine Arts, Dedication
• Hood, Gordon. The Ivan Wilson Center
• Downing, Dero. A Dedication Response
• Downing, Dero. Awareness & Willingness
• Dickey, Debbie. A Renewal of the Spirit
• Sutherland, David. Appalachia, A Stronghold of Early American Folk Culture
• Cann, Kenneth. If It's Guatemala …

General Theory Of Diffusion-Controlled Reactions, Gerald Wilemski, Marshall Fixman

Physics Faculty Research & Creative Works

A formal mathematical description of diffusion-controlled bimolecular reactions is presented. The theory is completely general with respect to the kinds of reaction processes that may be considered. Besides the presentation of the general formalism, the paper also contains several examples illustrating the application of the theory to a simple many-particule system for simple catalytic bimolecular reactions, including fluorescence quenching. The manner in which approximate solutions may be obtained is also outlined.

Production Of Metastable Ions In Cesium-Atom-Electron Collisions, Kaare J. Nygaard, Yu Bong Hahn

Physics Faculty Research & Creative Works

The structure in the total electron-impact ionization cross section in cesium can be partially accounted for by the mechanisms of autoionization and excitation ionization of 5p electrons. For electron energies above 17 eV a large fraction of the ions are metastable and can de detected by Auger emission from a metal surface. The experiment was performed in a cesium-atom-electron crossed-beam apparatus, and the metastable ions were counted with a channel electron multiplier. The metastable-ion count rate was a factor of 100 higher than that due to photons from atomic and ionic transitions. We have measured the over-all excitation function for …

Molecular Beam Measurements Of Total Collision Cross Sections Of H 22o, William R. Snow, J. T. Dowell, J. G. Chevrenak, H. E. Berek

Physics Faculty Research & Creative Works

The total cross section for H22O-H22O scattering is measured with a supersonic nozzle beam system. The primary beam has a narrow velocity distribution, and the velocity is varied by control of the nozzle temperature. Velocities are determined by time-of-flight techniques. Cross sections obtained are averages over a Maxwellian distribution of the target molecules. Data at three velocities are presented. The cross sections for H2O are surprisingly small, for example, 3.07 x10-14 cm2 at 1x105 cm/sec, indicating little contribution from the dipole-dipole interaction.

Chemical Shift Parameters For Shallow Donors In Semiconductors, Edward Boyd Hale

Physics Faculty Research & Creative Works

A model for a shallow donor impurity in a semiconductor is used to calculate two relationships and several conditions involving the chemical shift parameters. The model is based on the standard effective mass form for the donor electron wave function, the existence of a potential in the chemical cell which may be real, pseudo, or rather general in nature, and a few somewhat restrictive approximations. The parameters, Δ, δ and Λ are theoretically calculated and are shown to be related if the approximations are valid. These parameters determine the 1S multiplet level structure and it is shown how properties of …