Digital Commons Network^™

Supralinearity Of Thermoluminescent Dosimeters, Leif Larsson, Robert Katz

Robert Katz Publications

The supralinear response of thermoluminescent dosimeters (TLDs) after irradiation with gamma- or beta-rays can be decomposed by use of the cumulative Poisson distribution into a sum of 1-or-more and 2-or-more hit components, suggesting the coexistence of both types of trap structures. Following the response of other 1-hit detectors, and of biological cells to energetic heavy ions, we expect and find that the supralinear response tends to disappear with alpha particle, and with neutron irradiation, and that the supralinear, or 2-hit, component tends to be more responsive to high LET (Linear Energy Transfer) radiations. Since the response of biological cells to …

The Quantum Defect Theory Approach, Anthony F. Starace

Anthony F. Starace Publications

The Quantum Defect Theory (QDT) is a method of using the analytically known properties of excited electrons moving in a pure Coulomb field to describe atomic photoabsorption and electron-ion scattering processes in terms of a few parameters. These parameters may be determined either from experimental data or from ab initio theoretical calculations. In addition, they are usually nearly independent of energy in the threshold energy region (i.e., within a few eV of the atomic ionization threshold). Thus the determination of these parameters at any single energy suffices to predict the variation with energy of numerous atomic properties in the threshold …

18th Annual Rocky Mountain Spectroscopy Conference

Rocky Mountain Conference on Magnetic Resonance

Final program and abstracts from the 18th 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 2-3, 1976.

Cross Sections For Excitation Of Atomic Hydrogen To The N=2, 3, And 4 States By 15-200-Kev Protons, John T. Park, John E. Aldag, Jacob M. George, Jerry Peacher

Physics Faculty Research & Creative Works

Cross sections for the processes H⁺+H(1 s)H⁺+H*(n = 2, 3, 4) have been extracted from the energy-loss spectra of 15- to 200-keV protons by using a spectrum-fitting technique. Absolute cross sections have been obtained by normalization of the spectra to the theoretical cross section through the use of the Born approximation at 200 keV. The cross-section curves are very similar in shape with maxima at 60 keV. The results have been compared with available theoretical calculations. The n = 2 and n = 3 cross-section measurements are in very good agreement in curve shape with Glauber-approximation …

Electrical Conductivity Of Thin Lecithin-Cholesterol Membranes Due To 2,4-D, 2,4-Db, 2,4,5-T And 2,4-Dcp, Malkanthi Paulis

Dissertations and Theses

The effect of the following pesticides on DC electrical conductivity of lecithin-cholesterol membranes has been studied: endothall, paraquat, diquat, 2,4-D, 2,4-DB, 2,4,5-T, 2,4-DCP. It has been found that the ions of endothall, paraquat and diquat are essentially membrane impermeable and that they do not bind to the membrane surface. In contrast, 2,4-D, 2,4-DB, 2,4,5-T and 2,4-DCP induce electrical conductivity in lecithincholesterol membranes and in addition they also cause an increase in the nonactin-K⁺ membrane conductivity.

The compounds 2,4-D, 2,4-DB, 2,4,5-T and 2,4-DCP basically behave as class II uncouplers. The kinetic scheme of charge transfer across the membrane, based on …

Systematic Evaluation Of Cellular Radiosensitivity Parameters, R. A. Roth, S. C. Sharma, Robert Katz

Robert Katz Publications

Cellular radiosensitivity parameters of the track structure theory of Katz and co-workers are evaluated from a sum of squares minimizing computer program for nonlinear models. Based on these observations, suggestions are presented for efficient experiment design for the determination of these parameters from track-segment bombardments of high LET radiations.

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

Physics Faculty Research & Creative Works

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 …

Frequency-Mixing Detection (Fmd) Of Polarization-Modulated Light, R. M.A. Azzam

Electrical Engineering Faculty Publications

When a light beam whose polarization and intensity are weakly modulated at a frequency ω_m passes through a periodic analyzer of frequency ω_a(<ω_m) and the transmitted flux is linearly detected, the resulting total signal S_t consists of two components: (i) a periodic baseband signal S_bb with harmonics of frequencies nω_a (n = 0,1,2,…) and (ii) an amplitude-modulated-carrier signal δS_mc with center (carrier) frequency ω_m and sideband frequencies at ω_m ± nω_a(n = 1,2,…). In this paper we show that the average polarization of the beam is determined …

Modulated Generalized Ellipsometry, R. M.A. Azzam

Electrical Engineering Faculty Publications

We extend ellipsometry to the direct measurement of small perturbations of the Jones matrix of any linear nondepolarizing optical sample (system) subjected to a modulating stimulus such as temperature, stress, or electric or magnetic field. The methodology of this technique, to be called Modulated Generalized Ellipsometry (MGE), is presented. First an ellipsometer with arbitrary polarizing and analyzing optics is assumed, and subsequently the discussion is specialized to a conventional ellipsometer having either the polarizer-sample-analyzer (PSA) or the polarizer-compensator-sample-analyzer (PCSA) arrangement. MGE provides the tool for the systematic study of thermo-optical, piezo-optical, electro-optical, magneto-optical, and other allied effects for both isotropic …

Observation Of Vibrationally Excited Nitrogen With A Simplified Electron Transmission Apparatus, J.A. Michejda, Paul Burrow

Paul Burrow Publications

A simple electron transmission apparatus is used to observe vibrationally excited N₂ in the first two vibrational levels. The method is based on the pronounced peaks appearing in the total electron scattering cross section in the range of energy 2–4 eV. Because of the wide spacing between these peaks, good energy resolution is not required and measurements can be performed without an electron monochromator.

Reply To “Comments On ‘Theoretical Study Of Impurity-Induced First-Order Raman Spectra For The Alkali Halides’”, John R. Hardy, Arnold Karo

John R. Hardy Papers

This is a reply to the preceding comment by Page on the relative merits of the breathing-shell and deformation-dipole models for predicting defect-activated first-order Raman spectra. We show that when both models are parametrized in the same fashion the agreement between theory and experiment is comparable.

Photoinization Cross Sections For Atomic Chlorine Using An Open-Shell Random-Phase Approximation, Anthony F. Starace, Lloyd Armstrong Jr.

Anthony F. Starace Publications

The use of the random-phase approximation with exchange (RPAE) for calculating partial and total photoionization cross sections and photoelectron angular distributions for open-shell atoms is examined for atomic chlorine. Whereas the RPAE corrections in argon (Z=18) are large, we find those in chlorine (Z=17) to be much smaller due to geometric factors. Hartree-Fock calculations with and without core relaxation are also presented. Sizable deviations from the close-coupling results of Conneely are found.

Multiple Rainbows From Single Drops Of Water And Other Liquids, Jearl D. Walker

Physics Faculty Publications

The scattering of light by spherical drops and the theory of rainbows are reviewed in detail to predict the angular positions of rainbows from single drops. The angular positions of the first 13 rainbows of water, observed from a drop suspended in a student spectrometer, were compared to these theoretical positions. Since the rainbows were dependent on the refractive index, the positions shifted with drops of other fluids having other refractive indices. Light corn syrup yielded 11 rainbows, including the 17th-order one. The light emerging from the drops was white except for the multicolors of the rainbows and the faint …

Debye–Hückel Theory For Rigid‐Dipole Fluids, John D. Ramshaw

Physics Faculty Publications and Presentations

The dipolar analog of classical linearized Debye–Hückel theory is formulated for a finite fluid system of arbitrary shape composed of rigid polar molecules. In contrast to the ionic case, the dipolar Debye–Hückel (DDH) theory is nonunique due to an inherent arbitrariness in the choice of a local field E*. This nonuniqueness is expressed in terms of a parameter ϑ related to the ellipticity of the spheroidal cavity used to define E*. The theory then leads to an expression for the direct correlation function c (ϑ) as a function of ϑ. Only the short‐range part of c (ϑ) depends upon ϑ; …

Metamagnetism In Single Crystal Γ-Co(Pyridine)2Cl2, S. Foner, Richard B. Frankel, W. M. Reiff, H. Wong, Gary J. Long

Physics

Small (≤1 mg) single crystals of γ-Co(pyr)₂Cl₂ have been grown and measurements of magnetic moment vs applied field H and temperature have been made for 0≤H≤54 kG and 1.25 K≤T≤4.2 K. At 1.25 K, metamagnetic transitions are observed along the a-axis at ~700 G; along the b-axis at both ~800 and ~1500 G; and along the c-axis at ~4 kG. The low field susceptibilities show a maximum at T≃3.4 K for each orientation. Magnetic saturation is not achieved at 54 kG; about 2.5 µ_B is achieved along the a*- or b-axes, whereas a lower moment is …

Hyperfine Interactions In Antiferromagnetic Eute Using The Te-125 Mossbauer Resonance, N. A. Blum, Richard B. Frankel

Physics

Europium telluride crystallizes in the NaCl structure and is antiferromagnetic with a Néel temperature TN of 9.6 K. We have used the 35.5 keV Møssbauer transition in Te-125 to examine the nature of the spontaneous magnetic moment which has been observed in conducting samples below TN. At 80 K the Mössbauer resonance spectrum consisted of a single absorption line comparable in width with the spectrum of nonmagnetic cubic ZnTe, indicating the absence of a significant quadrupole splitting at this temperature. At 4.2 K the line-width increased by a factor of 1.5, which is equivalent to a single magnetic hyperfine field …

Evidence Favoring Nonevolutionary Cepheid Masses, Norman R. Simon, Edward G. Schmidt

Edward Schmidt Publications

It is suggested that the bumps on the velocity curves of nonlinear Cepheid models may be understood as the consequence of a resonance between the fundamental and the second overtone modes of the pulsating star. Thus the presence of bumps can be inferred from linear calculations. The region of the observational instability strip containing bumps is compared with the location of the calculated resonances. As was the case for the nonlinear calculations, we find that masses considerably less than evolutionary values are required to bring agreement between the observations and the theory.

Hall-Effect Measurements In Cd-Implanted Gaas, B. K. Shin, David C. Look, Y. S. Park, J. E. Ehret

Physics Faculty Publications

Cadmium ions were implanted in GaAs crystals at 135 keV to doses ranging from 10¹² to 10¹⁶ ion/cm² at room temperature. Sheet‐resistivity and Hall‐effect measurements were carried out as a function of temperature, 4.2–300°K, after annealings at 700, 800, or 900°C in an Ar ambient. The sample surfaces were protected with pyrolytically deposited Si₃N₄. Significant p‐type conduction was observed when samples with doses ≳10¹³cm⁻² were annealed at ≳700°C. For doses below 10¹⁴ cm⁻² nearly complete electrical activity was attained after an 800–900°C anneal. The Cd profiles were …

Intermetallic Reactions In Vacuum-Deposited Nickel And Gold Films On (111) Silicon Single Crystals, K. H. Yoon, Gordon Lewis, L. L. Levenson

Materials Science and Engineering Faculty Research & Creative Works

Pure nickel and gold thin films were vacuum-deposited on (111) silicon single crystals. When Ni/Au/Si or Au/Ni/Si samples were heated to about 550° in situ, hexagonal or deformed hexagonal shaped crystallites were formed on the silicon substrates. The composition of these crystallites was determined by using x-ray diffraction, scanning electron microscopy and scanning Auger microprobe methods. The crystallites were identified as NiSi2. The crystal-lites on the (111) silicon plane parallel to the surface appeared as regular hexagons while the inclined crystal-lites resembled trapezia. The results of Auger spectra and in-depth composition profiles for Ni, Au, and Si showed that the …

The Effect Of A Magnetic Field On The Leclanché Cell, Walter Edward Socha

Dissertations and Theses

The effect of a magnetic field on an electrochemical system, the Leclanche cell, was investigated. Experiments show that there is an increase power output and charge passed when a cell is discharged in an applied magnetic field.

Possible explanations for the effect and descriptions of attempts to verify these explanations are presented.

"Nuclear Power: Its Role In Our Future", Betsy Macinness, Dave Ferg, Rudi Nussbaum, Tom Davis, Sandra Kiefer

Special Collections: Oregon Public Speakers

No abstract provided.

Efficient Ci Calculations Utilizing The Symmetric Group, Gordon A. Gallup, J.M. Norbeck

Gordon Gallup Publications

Gallup has recently given a solution to the problem of determining an orthogonal representation matrix for an arbitrary permutation of the symmetric group in terms of sandwich representations. In this paper it is shown how this provides a means for the precalculation and storage of the necessary distinct coefficients needed in the construction of the various Hamiltonian matrix elements of an orthogonal orbital CI calculation. This method has the advantage over those published previously in that the spin degeneracy problem is handled more efficiently. It is shown that this procedure can be utilized with both the "construction and storage" algorithms …

Raman Spectrum Of Gadolinium Molybdate At 80°K, B.N. Ganguly, Frank G. Ullman, Roger D. Kirby, John R. Hardy

Roger Kirby Publications

Lines that overlap from thermal broadening in the room-temperature Raman spectrum of gadolinium molybdate are resolved in the 80°K spectrum. A total of 126 of the possible 201 lines have been resolved. Symmetry assignments are derived from considerations of both point symmetry and polariton dispersion, supported by separate measurements of A1(TO) and A1(LO) spectra. The splitting of the unstable 47 cm-1 room-temperature A1(TO) line into a doublet at 44.5 and 51.5 cm-1, observed previously only in ir absorption, is also observed in these spectra. On heating, the 44.5-cm-1 line remains fixed in frequency whereas the 51.5-cm-1 line broadens and shifts …

(R - I) Colors Of Cepheids And Yellow Supergiants In Open Clusters, Edward G. Schmidt

Edward Schmidt Publications

(R - I ) and (b - y) observations of nine Cepheids which are members of open clusters, 14 field Cepheids, and 34 nonvariable yellow giants in or near open clusters are presented. Colorcolor relations for the Cepheids are found to differ significantly from star to star. Additionally, the nonvariables may differ from the Cepheid color-color relation. Pulsational masses are determined for the Cepheids using both (R - I) and (B - V) colors as temperature indicators. For some of the shorter period stars the (R - I) masses agree with evolutionary masses, which is not the …

Four-Color And Hβ Photometry Of The Galactic Cluster Ngc 6633, Edward G. Schmidt

Edward Schmidt Publications

Photometric measurements of stars in the intermediate-age galactic cluster NGC 6633 are presented. From these data the color excess is found to vary slightly across the cluster with an average of E_{b – y} = 0^m.124. The distance modulus is found to be 7^m.711 and the turnoff occurs at about (b – y)₀ = 0^m.l. The cluster is slightly metal poor.

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.