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Ionization Enhanced Diffusion, David Peak, J W. Corbett, J Bourgoin

All Physics Faculty Publications

The general three‐dimensional diffusion equations, along with the corresponding tensor diffusivities, are established for the normal ionization‐enhanced diffusion mechanism (which is equivalent to a general two‐channel diffusion mechanism) and for the Bourgoin mechanism, the latter being explicitly developed for the diamond lattice.

Comparison Of Experimental And Theoretical Electron Ejection Cross Sections In Helium By Proton Impact From 5 To 100 Kev, M. Eugene Rudd, D. H. Madison

M. Eugene Rudd Publications

Absolute values of doubly differential cross sections are obtained for electron production in helium by 5- to 100-keV proton impact. The measured values along with earlier data at higher energies are compared with theoretical plane-wave Born-approximation functions obtained from a Hartree-Fock potential. Not only is good agreement obtained at high impact energies (above 300 keV), but fairly good agreement is found at low energies (below about 20 keV). For electrons ejected in the backward hemisphere, unexpectedly poor agreement is noted at intermediate energies where the measured cross sections dip to 50% of the calculated values in some cases. Singly differential …

Simplified Rbe-Dose Calculations For Mixed Radiation Fields, Robert Katz, B. G. Fullerton Jr., R. A. Roth, S. C. Sharma

Robert Katz Publications

A problem for radiobiology, radiation protection and treatment planning is the calculation of RBE as a function of the delivered dose when this dose is a result of a mixture of low and high LET radiations, as for neutron and pion beams. Track structure theory (Katz and Sharma, 1975) has recently been used to produce an algorithm for calculating survival, RBE, and OER as a function of dose in such environments. This simple formulation is based on the concept of irradiation equivalence (Katz et al., 1972) through which the effect of a mixed radiation environment is calculated as if it …

Electron-Phonon Interaction In Impure Cadmium, Paul D. Hambourger

Physics Faculty Publications

No abstract provided.

Impurity-Concentration Profile For An Exponentially Decaying Diffusion Coefficient In Irradiation Enhanced Diffusion, J Kowall, David Peak, J W. Corbett

All Physics Faculty Publications

The diffusion equation is solved for a semi-infinite region in the case of irradiation-enhanced diffusion produced by a diffusion coefficient falling off exponentially in the medium. Near the surface the concentration profile due to enhanced diffusion has a larger concentration than the profile due to thermal diffusion; conversely far from the surface the enhanced-diffusion profile has a lower concentration than that due to thermal diffusion. Thus, this type of enhanced diffusion results in a more abruptly changing profile than does thermal diffusion.

Competitive Effect On The Rate Of The Diffusion-Controlled Reaction A+B→C, David Peak, K Pearlman, P J. Wantuck

All Physics Faculty Publications

None available; appears in letters section.

Thomson's Monopoles, I. Adawi

Physics Faculty Research & Creative Works

The angular momentum L of the electromagnetic field due to an electric point charge e, and a magnetic point charge (pole) g, is calculated by several methods to obtain J. J. Thomson's result that L = eg/c, and L is directed along the line joining the electric monopole to the magnetic monopole. The relation to Dirac's monopoles is discussed, and particle size is considered. © 1991, American Association of Physics Teachers. All rights reserved.

Radiative Lifetimes Of Some Group Ii Ions By The Hanle Effect In A Fast-Flowing Helium Afterglow, F. H.K. Rambow, Laird D. Schearer

Physics Faculty Research & Creative Works

Radiative lifetimes of the first P322 state of Mgu, Cau, Znu, Sru, Cdu, and Bau are reported as measured by the Hanle effect in a fast-flowing helium afterglow. They are, respectively, 3.65(0.12), 6.61(0.30), 2.4(0.3), 6.64(0.10), 2.86(0.25), 6.78(0.40) in units of 10-9 sec. The ions in the afterglow are created by Penning ionization of the neutral metal atoms, thus providing a steady-state, field-free region for observation. Comparisons are made with measurements by other methods, and discrepancies are discussed. © 1976 The American Physical Society.

The Martensite Transformation, Manfred Wuttig, Tetsuro Suzuki

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Nuclear Spin Relaxation By Intramolecular Interactions In Gases Of Homonuclear Diatomic Molecules, Myer Bloom, Peter A. Beckmann, B C. Sanctuary

Physics Faculty Research and Scholarship

The differential equations which describe the relaxation of macroscopic observables associated with nuclear spins in homonuclear diatomic molecules are derived using an expansion of the nuclear spin density matrix in terms of irreducible tensors. It is shown, using an intramolecular quadrupole mechanism, that the only difference between nuclear spin relaxation of the ortho- and para-species arises from the rotational states being restricted to odd and even values. This difference is vanishingly small at high temperatures so that the relaxation equations for nuclear magnetization become identical for both species. A previous paper predicting a difference even at high temperatures is …

Proton Spin Relaxation In Dilute Methane Gas: A Symmetrized Theory And Its Experimental Verification, Peter A. Beckmann, M. Bloom, I. Ozier

Physics Faculty Research and Scholarship

Nuclear spin relaxation in low density methane gas is investigated theoretically and experimentally. A theory is developed in which full account is taken of the tetrahedral symmetry of the molecule. For a nuclear Larmor frequency of 30 MHz, the time evolution of the nonequilibrium magnetization is measured as a function of density between approximately 0.005 and 17 amagats at temperatures of 110, 150, and 295 K. In all cases, exponential relaxation is observed. By using the theory in conjunction with the known spin rotation constants and rotational energy levels of CH₄, the measured values of the relaxation rate …

Radiative Lifetimes And Alignment Depolarization Cross Sections For Ybi And Ii By The Hanle Effect In A Flowing Helium System, F. H.K. Rambow, Laird D. Schearer

Physics Faculty Research & Creative Works

The radiative lifetimes of the 17992-,25068-,28857-, 37414-, 40564-, and 44017-cm-1 neutral levels and the 30392-cm-1 ion level of Yb have been measured by the Hanle method in a fast-flowing He system. The lifetimes (in units of 10-9 sec) were found to be 820(20), 5.12(0.12), 14.4(0.4), 77.4(6.0), 9.32(0.6), 39.1(3.5), and 5.8(0.6), respectively. In a flowing system with He as a buffer gas the alignment depolarization cross sections with Yb were obtained and are reported here for the first time. They are (in units of 10-15 cm2) 5.0(1.0), 5.9(1.0), 5.9(1.2), 17.9(2.0), 28.2(3.0), 5.16(4.0), and 7.2(2.5), respectively. © 1976 The American Physical Society.

Low-Energy Electron Scattering From Mg, Zn, Cd And Hg: Shape Resonances And Electron Affinities, Paul Burrow, J.A. Michejda, J. Comer

Paul Burrow Publications

Measurements of electron scattering at low energy from Mg, Zn, Cd and Hg have been carried out using the electron transmission method. A large shape resonance is observed for each element which we identify with the (ns²np)²P ground state of the negative ion. The electron affinities in eV are found to be Mg(–0.15), Zn(–0.49), Cd(–0,33) and Hg(–0.63) with an error of ±0.03 eV. The results are compared with the available theoretical predictions.

Photoconductivity In Bone And Tendon, Robert G. Fuller, A. A. Marino, R. O. Becker

Robert G. Fuller Publications

Ultraviolet light can be used to stimulate electrical current flow in bone and tendon. This stimulated photocurrent is directional. In tendon the photocurrent parallel to the fibrils is greater than the photocurrent perpendicular to the fibrils. In bone, the longitudinal photocurrent is less than the transverse photocurrent.

Surface Electromagnetic Waves With Damping. I. Isotropic Media, G. S. Kovener, Ralph William Alexander, Robert John Bell

Physics Faculty Research & Creative Works

Surface-Electromagnetic-Wave Dispersion Curves Are Usually Calculated using a Simple Equation Derived from Maxwell's Equations and Boundary Conditions. When Complex Dielectric Functions Are Used for the Two Media, the Component of the Propagation Vector Along the Surface, Kx, Becomes Infinite as the Frequency Approaches the Surface Polariton Frequency Ωs If Ω is Considered Complex and Kx is Real. on the Other Hand, If Kx is Considered Complex and Ω Real, the Dispersion Curves Bend Back Toward Smaller Kx as Ω Approaches Ωs. We Have Previously Demonstrated that Both Types of Behavior Can Be Obtained from Attenuated-Total-Reflection Measurements of Silver. We Now …

Model System Studies Of Axial Ligation In The Oxidized Reaction States Of Cytochrome P-450 Enzymes, R. H. Holm, S. C. Tang, S. Koch, G. C. Papaethymiou, S. Foner, R. B. Frankel, J. A. Ibers

Physics

No abstract provided.

H I In Early-Type Galaxies. Ii. Mass Loss And Galactic Winds, S. M. Faber, J. S. Gallagher

Department of Physics and Astronomy: Faculty Publications

Implications of observed upper limits to the neutral hydrogen content of E and SO galaxies from Paper I are discussed. If gas shed by dying stars is completely retained by these galaxies and exists as H I, these upper limits will be exceeded in only 10⁹ yr for E's and SO's and in only 2 x 10⁸ yr for NGC 4472. Evidently, gas either is hidden in some undetectable form or is removed from the interstellar medium completely.

Some Applications Of Lie Transformation Groups To Classical Hamiltonian Dynamics, Donald Robert Peterson

University of the Pacific Theses and Dissertations

Recent work has established that a group theoretical viewpoint of completely integrable dynamical systems with N degrees of freedom yields an algorithm that provides new information concerning the symmetry transformation group structure of this class of dynamical systems. The work presented here rests heavily on the results presented in reference and it is recommended that the reader consult this reference for a more rigorous discussion of the results given in this thesis.

Surface Electromagnetic Wave Mode And Field Analysis In A Metal-Metal-Oxide-Air System With Damping, C. A. Ward, Ralph William Alexander, Robert John Bell

Physics Faculty Research & Creative Works

An Explanation is Provided for the Surface Electromagnetic Wave (SEW) Energy Ejection from a Thin Film at the Longitudinal and Transverse Optical-Phonon Frequencies of the Film Material. Field Ratio Calculations Identify Previously Discussed Metal-Metal-Oxide-Air SEW Modes as Those Expected from the Berreman Configuration, and It is Shown that Greenler Technique High-Incidence-Angle-Reflectance Data on the Same System May Be Similarly Interpreted. © 1976 the American Physical Society.

Note On Amorphous Magnetic Materials, Louis H. Lund

Physics Faculty Research & Creative Works

No abstract provided.

The Magnification Factor For Sodium Chloride Liesegang Circles Established With An Aerosol Centrifuge, O. Preining, Josef Podzimek, P. Yue

Physics Faculty Research & Creative Works

Sodium chloride particles deposited on a gelatin film containing silver nitrate form in a humid environment clearly visible dark brown reaction spots (Liesegang circles) after development in u.v.-light. The size of these reaction spots depends on the mass of NaCl in the particles. To establish the spot size vs particle size relation, particles produced by nebulising NaCl-solutions and sea water were sampled in an aerosol centrifuge. The location of deposition yields the aerodynamic diameter of the particle, and the spot size is measured microscopically. In this way the spot size vs aerodynamic diameter relation is established experimentally in the so …

Numerical Simulation Of A Widely Used Cloud Nucleus Counter., Darryl J. Alofs, J. C. Carstens

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Performance of the Conventional Horizontal Plate Thermal Diffusion Chamber as a Cloud Nucleus Counter Was Studied. Numerical Calculations Were Performed in Order to Follow the Simultaneous Drop Growth and Sedimentation in the Spatially and Temporally Nonuniform Supersaturation Field. the Effect of Nuclei Distribution and Smallest Detectable Drop Size Were Investigated. the Results Indicate Order of Magnitude Uncertainty in the Count at 0. 1% Supersaturation, and a Factor of 2 Uncertainty at 1. 0% Supersaturation.

Group Of Point Transformations Of Time Dependent Harmonic Oscillators, Jose Ricardo Bernal

University of the Pacific Theses and Dissertations

In general, a physical system has invariant quantities which are very often related to its symmetry and to the invariance of the equation that describe it. A detailed study of the invariance property of the differential equation will be helpful in understanding this relation.

The work is concerned with a preliminary investigation of the Lie-group which leaves invariant the Newtonian and Lagrangian equation of motion for a one-dimensional harmonic oscillator. A brief review of Ehrenfest's adiabatic principle and the later treatments on exact and adiabatic invariants will be presented.

Video Tape : An Old-New Instructional Aid In The Physics Laboratory, Fanny Mercedes Torres Holguin

University of the Pacific Theses and Dissertations

My objective is to use the video-tape as another medium -- along with overhead projector, textbooks, guides of apprenticeship, pictures, lab equipment and suggestions from the programs and new trends in physics teaching -- being used to supplement our efforts in trying to reach more and more of our students The use of audiovisual media, and generally speaking the use of technology in education, can be constructive or destructive, can e very powerful in developing "human beings" or "robots", can increase the rate of apprenticeship, or can produce an educational catastrophe. However, it will heavily depend on the the professor, …

Absorption In The Infrared Of Surface Electromagnetic Waves By Adsorbed Molecules On A Copper Surface, K. Bhasin, D. Bryan, Ralph William Alexander, Robert John Bell

Physics Faculty Research & Creative Works

Experimental Observations Have Been Made for the First Time that Surface Electromagnetic Wave (SEW) Spectroscopy Can Be Used to Measure the Infrared Spectra of Adsorbed Molecules and Very Thin Films on Metal Surfaces. using a Tunable CO2 Laser (9.2-10.8 Μm Wavelength), the 975 and the 1037 Cm-1 Resonances of 5-25 Å Thick Physiosorbed Benzene on Copper Were Observed. Broadening of These Resonances for the Thinnest Layers of Benzene Was Observed. Also SEW Spectroscopy and Ellipsometry Were Used to Study Thin Films of Cellulose Acetate (15-75 Å) on Copper. Further, It Was Shown that Film Thicknesses Determined by SEW Spectroscopy Are …

Comment On "Clustering Of Water On Hydrated Protons In A Supersonic Free Jet Expansion", James L. Kassner, Donald E. Hagen

Physics Faculty Research & Creative Works

No abstract provided.

Geophysical Institute Annual Report 1975-76, Geophysical Institute

GI Reports

The 1975-76 Geophysical Institute Annual Report presents an overview of the year’s scientific research achievements across the Institute’s disciplines, alongside operational summaries covering finances, administrative changes, and other key activities.

Neutron Spectra At Zero Degrees From Proton Bombardment Of Light Nuclei At Medium Energies, Constantine George Cassapakis

Physics & Astronomy ETDs

The neutron-momentum spectra at 0° resulting from proton bombardment of 9Be, 12C, and 27Al at Tp=633MeV, and those of 12C and 27Al at Tp=786 MeV, have been measured at the LAMPF (Los Alamos Meson Physics Facility)-Nucleon Physics Laboratory.

The measurements utilized the recently developed single arm, multiwire proportional counter, recoil-proton, magnetic spectrometer. I

dentification of the recoil charged particles was achieved through momentum analysis and simultaneous time­of-flight determination for each particle constituting a valid event.

The momentum and energy resolutions achieved are about 1% and 1.4%, respectively, at the incident proton energies considered.

The spectra for 9Be and 27Al exhibit …

Ultraviolet Excitation Thermoluminescence Of Lead-Manganese Calcium Carbonate, Dennis Schrope

Masters Theses & Specialist Projects

Calcium carbonate with impurities of lead and manganese have produced measurable thermoluminescence (TL) when excited by ultraviolet (uv) radiation. In this investigation the lead impurities comprise the majority of trapping centers stimulated by uv irradiation. In addition, centers associated with the CO₃groups have been found to be capable of absorbing uv and ultimately producing TL. The 2537 Å mercury line is primarily responsible for stimulating these centers, and the response was found to be linear to 0.6734 joules/cm².

The thernoluminescence response was discovered to be dependent on the concentrations of lead and manganese. However, for a …

Saturation Effects In A Tunable Coherent Near-Infrared Source, Israel L. Tyler, R. (Ralph) W. Alexander, R. (Robert) J. (John) Bell

Physics Faculty Research & Creative Works

A Saturation Effect in a Tunable Infrared Source Utilizing Four-Wave Parametric Conversion in Potassium Vapor is Reported and is Shown to Be the Result of Parasitic Oscillations. a Hundredfold Increase over Previously Attained Power Levels Has Been Affected Via Elimination of These Oscillations.