Digital Commons Network^™

On The Physical Properties Associated With Omega Phase In Titanium-Chromium Alloys, Serag El Din El Sayed Habib

Archived Theses and Dissertations

No abstract provided.

Shell Source Burning Stars With Highly Condensed Cores, S. Refsdal, A. Weigert

Department of Physics and Astronomy: Faculty Publications

Simple analytical relations are derived - similar to the homology relations for homogeneous stam - which describe the behaviour of shell source burning models with highly condensed cores. Many features which are known from evolutionary calculations (and partly &om observations) of such stars can be understood as coming essentially from the increase of the mass M₆ of the core.

Experimental Evidence For The Mechanism Of Charge Transfer Into Continuum States, G. B. Crooks, M. Eugene Rudd

M. Eugene Rudd Publications

We have observed a prominent peak in the energy spectrum of electrons ejected in the forward direction from helium bombarded by protons ranging in energy from 100 to 300 keV. The peak occurs at an ejected-electron velocity equal to the velocity of the incident proton. The experimental results verify the existence of the mechanism of charge transfer into continuum states of the incident ion.

Emission Of Auger Electrons Resulting From Symmetric Argon And Neon Ion-Atom Collisions, R. K. Cacak, Q. C. Kessel, M. Eugene Rudd

M. Eugene Rudd Publications

Cross sections for the emission of Auger electrons from excited atoms and ions produced in symmetric Ar⁺-Ar and Ne⁺-Ne collisions have been measured at ion energies from 50 to 300 keV. A simple model is proposed to explain the dependence of the cross section on the impact energy; the predicted results agree well with the experiment. Also, the argon x-ray data of Saris and Onderdelinden are compared with the model and with the results of this experiment.

Auger Electrons From Argon With Energies 150-210 Ev Produced By H+ And H2 Impacts, D. J. Volz, M. Eugene Rudd

M. Eugene Rudd Publications

Secondary electrons in the energy range 150-210 eV produced by 125-300-keV H⁺ and H₂⁺ impacts on argon gas are measured as a function of their energy and angle of emission. Discrete line spectra are due to Auger transitions from L₂ and L₃ vacancy states as well as satellite transitions from multivacancy states. The widths, energies, and branching ratios of the L₂ and L₃ vacancy states are presented. Widths of these states are appreciably greater than those obtained with electron impact excitation. This can be attributed to the recoil velocities of the target atom …

(15) The Papers Of Robert H. Goddard, Volume Iii: 1938-1945 [Appendices], Robert H. Goddard, Esther C. Goddard, G. Edward Pendray

The Papers of Robert H. Goddard

Meticulously curated and edited by Esther C. Goddard and G. Edward Pendray, The Papers of Robert H. Goddard is a 1700-page 3 volume set published in 1970. The set presents a careful and exhaustive chronological presentation of Robert Goddard’s life through diary snippets, correspondence, publications, speeches, patent outlines, school papers, press, reports and more.

These are the Appendices across all three volumes of The Papers of Robert H. Goddard. They are split into six parts:

1. Affidavits Concerning Rocket and Other Ideas, 1924-1942
2. Description of Affidavits Selected as Important by Robert H. Goddard, 1933-1934
3. Published Articles and Papers …

(12) The Papers Of Robert H. Goddard, Volume Iii: 1938-1945 [1938: Pressure-Tank Rockets Concluded], Robert H. Goddard, Esther C. Goddard, G. Edward Pendray

The Papers of Robert H. Goddard

Meticulously curated and edited by Esther C. Goddard and G. Edward Pendray, The Papers of Robert H. Goddard is a 1700-page 3 volume set published in 1970. The set presents a careful and exhaustive chronological presentation of Robert Goddard’s life through diary snippets, correspondence, publications, speeches, patent outlines, school papers, press, reports and more.

This section covers the year 1938, concluding Goddard's work with pressure-tank rockets. Following this, he would focus his attention on developing turbine-driven pumps for liquid propellants.

This section contains correspondence by, to, and about Robert H. Goddard from the following people and entities: William R. Enyart, …

The Design And Construction Of A Constant Acceleration Drive System For Mössbauer Experiments, James Donald Russell

University of the Pacific Theses and Dissertations

An excited nucleus may undergo a transition to its ground state by the emission of a gamma ray. The nucleus, if free to do so, will recoil and take some of the transition energy as recoil energy leaving less energy for the emitted gamma ray. This gamma ray does not have enough energy to excite a similar nucleus and will, therefore, not by resonantly absorbed due to the fact that the natural linewidth of the gamma ray is so much smaller than the energy taken by the emitting atom and the similar energy needed by the absorbing atom.

In 1958 …

Realistic Impulsive P Wave Source In An Infinite Elastic Medium, Joseph Hugo Hemmann

Doctoral Dissertations

"The generally assumed instantaneous impulsive pressure sources for an elastic P wave in an infinite medium lead to basic contradictions, a step function source yielding infinite displacements as the shear modulus goes to zero, and the total energy radiated by a delta function (or any derivative of the delta function) source being infinite. By noting that the character of the solution in the elastic region must match the acoustic case near the source, a realistic impulsive pressure source is postulated which has a finite time history. The elastic field produced by this source is then obtained in closed form. A …

Theory Of Shallow Donor Impurity Surface States, Vidal Emmanuel Godwin

Doctoral Dissertations

"A variational approach has been used to solve the effective-mass equation, when the impurity ion is located at a depth d from the surface of a semiconductor, where 0 < d < d_b and d_b represents the case when the impurity ion is in the bulk of the semiconductor. The ground state and the excited state having the largest electric dipole coupling to the ground state have been determined. We have plotted the energy dependence on the depth of the impurity ion from the surface of the semiconductor. The energy has also been calculated as a function of the orientation of the …

A Quasi-Lattice Model Of Simple Liquids, Jesse Herbert Collins

Doctoral Dissertations

"A cellular model of simple liquids is proposed which eliminates the objectionable feature of long range order found in other cell models. The volume is divided into N identical spherically symmetric cells, each occupied by one molecule. The cell-center density distribution relative to an average given cell center forms a series of Gaussian peaks whose width is proportional to the square root of the distance from the given cell center. The number of cell centers and average radial distance represented by each of the peaks correspond to a face-centered cubic lattice. The molecular pair distribution function is determined for several …

Radiative Lifetime Of The A¹Π State And The Transition Moment Variation Of The Fourth Positive Band System Of Carbon Monoxide, Joseph George Chervenak

Doctoral Dissertations

"The lifetime of the A¹π state of carbon monoxide has been measured using a pulsed invertron excitation source and delayed coincidence measurement technique on the fourth positive system. Eighteen bands, originating from the upper states v' = 0 to 5, were examined at pressures between 500 and 50 microns, with no pressure dependence noted. The data were corrected for photon "pile up" and least-squares fitted to the sum of two exponentials. The transition moment was found to vary and was expanded about the r-centroid of the v' = 0 to v" = 0 transition. Oscillator strengths are calculated and compared …

Excitation Of Hydrogen Atoms By Fast Protons, Edward Ellis Fitchard

Physics Theses & Dissertations

In this thesis a theoretical study is made of excitation of hydrogenic atom by charged particles such as protons or electrons. The approximation to the cross section for an inelastic scattering process is obtained under the following radically simplifying assumptions. The projectile is represented in its initial and final state by plane waves. All distortions are neglected whether they originate in an inelastic process or an elastic deflections of the charged particle by the nucleus. The perturbation of the atomic orbits between which the projectile induces transitions is neglected. Nonrelativistic hydrogenic wave functions are used for the electronic states. In …

A Study Of Some Matrix Elements For The Four-Pion Decay Mode Of Neutral Bosons, George Victor Weller

Masters Theses

No abstract provided.

A Heavy-Ion Energy Loss Spectrometer, John T. Park, F. D. Schowengerdt

Physics Faculty Research & Creative Works

A high-resolution system for the measurement of the energy loss spectra of 20-250 keV heavy ions incident on gas targets is described. The high resolution is obtained by decelerating the ion beam to a low, well-defined energy before performing the energy analysis. The energy loss spectrum is determined by changing the accelerator energy to compensate for energy lost in collisions with the gas atoms. The system is arranged so that normal fluctuations in the accelerator's power supply do not affect the energy resolution. The resolving power of the system is 2.5x104. The primary proton beam has a detected WHM of …

Some New Approaches To Shallow Impurity States, Wayne E. Tefft, Robert John Bell, Harold V. Romero

Physics Faculty Research & Creative Works

A variational calculation of shallow surface impurity states including image-charge and anisotropic mass effects was performed using two different sets of orthogonal functions. The first set was obtained by varying the Bohr radius in the hydrogenic functions, separately for each state. In the second set the Bohr radius was allowed to become anisotropic, and the elements were separately treated as variational parameters. In each case it was shown that with certain restrictions on the variational parameters the set remained complete and orthogonal. General expressions for the energy eigenvalues for both the bulk and surface problem obtained from the first set …

Infrared Reflectivity Of Doped Insb And Cds, Thomas J. Mcmahon, Robert John Bell

Physics Faculty Research & Creative Works

The coupling of free carriers and lattice-vibrational modes in CdS and InSb was investigated by using reflectance measurements. When the free-carrier concentration is such that the longitudinal-optical-mode frequency is at or near the plasma frequency, the longitudinal mode takes on a mixed character and is shifted in a manner similar to that described by Varga in 1965, while the transverse mode remains fixed. The electron effective masses in such a situation can be determined with the lattice effects excluded. In the case of CdS, the polaron mass and additional absorption in the plasma mode above the longitudinal-optical phonon frequency must …

Charge-Transfer Cross Sections For Negative Ions On Atomic And Molecular Targets, W. (William) R. Snow, R. D. Rundel, R. Geballe

Physics Faculty Research & Creative Works

Charge-transfer cross sections for H^- on O, O₂, and NO₂; O^- on H, O, H₂, O₂, and NO₂; and C^- on H and O have been measured over an energy range of 0.5 to 4 keV using a modulated crossed-beam apparatus. The experimental cross sections are compared with theories of resonant and non-resonant charge transfer based on a two-state approximation. For the reactions H^-+O O^-+H, the cross sections are found to be consistent with detailed balancing. The effect of electron detachment on charge-transfer …

Heavy-Particle Energy-Loss Spectrometry: Inelastic Cross Sections For Protons Incident Upon Helium, John T. Park, F. D. Schowengerdt

Physics Faculty Research & Creative Works

A method is described whereby absolute cross sections are obtained from inelastic energy-loss spectra induced by ions incident upon gaseous targets at energies of 25-125 keV. Inelastic energy-loss spectra of helium for proton impact are presented. Apparent differential cross sections and absolute total cross sections are obtained from the spectra. Total cross sections for the sum of the 1S1→2S1 and 1S1→2P1 excitations are reported, along with estimates of the relative contributions of each. Total ionization cross sections, total cross sections for inelastic scattering, apparent energy distributions of ejected electrons, and partial ionic stopping powers are also reported. The excitation cross …

Entropy Of The Mixed State Of Some Low-Κ Type-Ii Superconductors, Don Carlos Hopkins, R. R. Rice, J. M. Carter, J. D. Hayes

Physics Faculty Research & Creative Works

The entropy of the mixed state of type-II superconductors with low κ(∼1) is studied for the alloys Pb_0.96Tl_0.04 and In_0.88Sn_0.12. The current theories are reviewed for approximations valid near Hc1 and near Hc2. The experiments show for the most reversible sample (Pb_0.96Tl_0.04) that (SB)_T of the mixed state depends only on temperature, and that (ST)_B increases linearly with B from its value for the superconducting state until it drops discontinuously to its normal state value at H_c2. There is no abrupt increase in the specific …

Formation Of Carbides On Tungsten Wires, W. J. Croft, Kaare J. Nygaard

Physics Faculty Research & Creative Works

It has been found that layers of tungsten carbide form on tungsten wires processed under ultra-high vacuum. The carbide is formed from carbon impurities in the volume of material.

Vibrational Excitation By Electron Impact Near Threshold In H2, D2, N2, And Co, Paul Burrow, G.J. Schulz

Paul Burrow Publications

The trapped-electron method is applied to the measurement of the slopes of the vibrational cross sections near their respective thresholds. Absolute values are obtained by normalization to positive-ion cross sections. The values obtained in H₂ are 43 for v=1, 0.72, for v=2, 0.04, for v=3, and 0.003, for v=4, in units of 10^-18 cm²/eV. The values for N₂ are 2.5 for v=1 and about 0.02 for v=2, whereas, the values for CO are much larger, i.e., 120 for v=1 and 2.4 for v=2. Various corrections that are …

Hyperfine Interaction In Gd In Diamagnetic, Metallic Hosts, Richard B. Frankel

Physics

Mössbauer effect data for dilute, paramagnetic Gd in the diamagnetic, metallic hosts YAl₂, YbAl₂ and Al are analyzed and yield a local conduction electron polarization contribution to the Gd hyperfine field of +140 kOe.

Interpretation Of A Unified Theory Of Gravitation And Symmetry Breaking, David Peak, A Inomata

All Physics Faculty Publications

The formalism of Moen and Moffat is interpreted as a Yang-Mills theory set in a space-time generally endowed with curvature and torsion.

Mössbauer Effect In The Ferroelectric Pbtio₃-Bifeo₃ Solid Solutions, C. M. Yagnik, James P. Canner, Robert Gerson, William Joseph James

Physics Faculty Research & Creative Works

The Mössbauer spectra of the system (PbTiO₃)_0.95(BiFeO₃)_0.05 have been studied from room temperature to 585°C. From the isomer-shift of 0.491±0.02 mmsec^-1 at room temperature, the ionicity is found to be 60% ± 20%. A discontinuity in the plot of isomer-shift versus temperature at T_c is observed. The quadrupole splitting at room temperature is 0.295 ± 0.02 mm/sec^-1. A dip in the Mössbauer fraction is observed at the Curie temperature.

Particle Tracks In Emulsion, Robert Katz, E. J. Kobetich

Robert Katz Publications

A new theory of track formation in emulsion accounts for the tracks of charged particles on the basis of a theory developed earlier for the response of biological molecules and NaI(T1) to energetic heavy ions. The probability that an emulsion grain will remain undeveloped when exposed to δ rays depositing a mean energy E is assumed to be e^-E/E₀ where E₀ is the dose at which l/e (37%) of the emulsion grains remain undeveloped, as in the one-or-more-hit cumulative Poisson distribution. The parameter E₀ incorporates variations in emulsion properties and processing conditions. Calculation of …

Nuclear Zeeman Effect In W182 In Iron, Richard B. Frankel, Y. Chow, L. Grodzins, J. Wulff

Physics

The Mössbauer effect in the 100-keV 2+→0+ transition in W182 was observed with dilute tungsten in iron alloy absorbers with concentrations from 0.5-5.0 at.%W at 4.2°K. From the Zeeman spectra in external longitudinal magnetic fields, the g factor of the first excited 2+ state was found to be 0.22±0.02, and the hyperfine field at tungsten nuclei in iron was found to be -708±25 kOe. The hyperfine interaction for Fe⁵⁷ in these alloys was also measured, and the results are compared with measurements on alloys of Fe with other 5d impurities and with neutron diffraction measurements.

A Technique For The Rapid Measurement Of Thermoelectric Power, G.R. Caskey, David J. Sellmyer, L.G. Rubin

David Sellmyer Publications

A new technique is described for rapid measurement of the thermoelectric power of rod-shaped specimens over a wide temperature range. The apparatus utilizes sensitive commercial dc amplifier for the sample and temperature gradient voltages and a multiple-point recorder for sampling these voltages as well as the sample temperature signal. The technique eliminates spurious thermal emf's in the leads and is based upon on-the-run recording of the sample and temperature gradient voltages as the temperature gradient slowly increases. As a test of this technique, the thermopower of pure nickel was measured between 4.2 and 300 K and the results are compared …

11th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 11th annual meeting of the Rocky Mountain Spectroscopy Conference, sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, August 4-5, 1969.

Nmr Determination Of The Conduction-Electron Hyperfine Interaction In Crystalline Cdo, David C. Look

Physics Faculty Publications

Measurements of the Cd¹¹³ nuclear-spin-lattice relaxation time T₁ and Hall effect in crystalline CdO, a degenerate semiconductor, have yielded the contact hyperfine strength of the conduction electrons at the nuclei. The product T₁T=168 sec °K, independent of temperature T and frequency ν for T=1.4,4.2, and 77-350 °K, and for ν=2-10 MHz. Taking the carrier concentration N=2.6×10¹⁹ cm^-3 independent of temperature to within 3% at 4.2, 77, and 300°K, and using an effective electron mass m_e^*=0.2m_e, we calculate an averaged electron probability density at the nucleus, 〈|φ_F(0)|^{2 …}