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Articles 1 - 17 of 17

Full-Text Articles in Physics

New Technique For Measuring Photonuclear Cross Sections And Its Application To The Cu63([Gamma],N)Cu62 And C12([Gamma],N)C11 Reactions , Lester L. Newkirk Jan 1951

New Technique For Measuring Photonuclear Cross Sections And Its Application To The Cu63([Gamma],N)Cu62 And C12([Gamma],N)C11 Reactions , Lester L. Newkirk

Retrospective Theses and Dissertations

No abstract provided.


Determination Of Optical Constants In The Near Infrared Of Evaporated Metal Films From Reflectance, Transmittance And Film Thickness Measurements , Max Spencer Oldham Jan 1949

Determination Of Optical Constants In The Near Infrared Of Evaporated Metal Films From Reflectance, Transmittance And Film Thickness Measurements , Max Spencer Oldham

Retrospective Theses and Dissertations

No abstract provided.


The Determination Of Gamma-Ray Energies With The Magnetic Lens Spectrometer , Erling N. Jensen Jan 1947

The Determination Of Gamma-Ray Energies With The Magnetic Lens Spectrometer , Erling N. Jensen

Retrospective Theses and Dissertations

No abstract provided.


Spectrochemical Analysis Of Fruit Tissue For Lead , Verlee Enid Sater Jan 1944

Spectrochemical Analysis Of Fruit Tissue For Lead , Verlee Enid Sater

Retrospective Theses and Dissertations

No abstract provided.


A Determination Of The Elastic Constants Of Beta Quartz , Erwin William Kammer Jan 1942

A Determination Of The Elastic Constants Of Beta Quartz , Erwin William Kammer

Retrospective Theses and Dissertations

It has been confirmed in previous researches in this laboratory that beta-quartz is piezoelectric. This property suggests the feasibility of measuring the dynamic elastic constants for this substance utilizing the piezoelectric effect as a means for setting up vibrations. A method of measuring frequencies of vibration for parallelopipeds of beta-quarts is described. The technique involves driving the plates with a frequency modulated carrier and detecting beat notes which are amplified and placed on an oscilloscope screen for ease of observation. High order harmonics of the resonances are measured under conditions which permit the plates to be treated as having essentially ...


Comparison Of Granularity And Speeds Of Different Types Of Photographic Films , Christopher Ernest Barthel Jr. Jan 1940

Comparison Of Granularity And Speeds Of Different Types Of Photographic Films , Christopher Ernest Barthel Jr.

Retrospective Theses and Dissertations

No abstract provided.


Measurement Of Cathode Emission By Use Of The Electron Microscope , Francis Meade Bailey Jan 1940

Measurement Of Cathode Emission By Use Of The Electron Microscope , Francis Meade Bailey

Retrospective Theses and Dissertations

The electron emission from cathode surfaces changes rapidly with temperature. The difficulty of measuring the true temperature of surfaces such as that of Barium or strontium oxide has led to the development of a comparison method in which two or more materials may be heated under identical conditions. An electron micro-scope system was used to segregate the emission from each material, the current density measurement being made photographically;Curves for Dushman's equation were plotted as a check on the reliability of the method. The apparatus was used to prepare a table of the relative emission obtained from a few ...


The Determination Of Elastic Constants By Piezo-Electric Methods , Philip James Hart Jan 1939

The Determination Of Elastic Constants By Piezo-Electric Methods , Philip James Hart

Retrospective Theses and Dissertations

The relationships existing between the elastic constants and the frequencies of the natural modes of vibration of a finite plate of homogeneous material have never received a rigorous formulation. On the other hand, the solution of the relationships between elastic constants and natural frequencies of an infinite plate is rigorous;In the evaluation of the elastic constants of a material, an infinite plate can be approximated, either by making use of large, thin quartz plate or by using harmonica of the fundamental modes of vibration. The latter method was used in this investigation because of its greater accuracy;When a ...


The Dielectric Constant Of Gases At Ultra-High Frequencies , Alden Hoover Ryan Jan 1939

The Dielectric Constant Of Gases At Ultra-High Frequencies , Alden Hoover Ryan

Retrospective Theses and Dissertations

An experiment was conducted to determine the dielectric constant of three typical gases (nitrogen, carbon dioxide, and ammonia) at an ultra-high radio frequency and to ascertain if there was any change of the dielectric constant with the frequency;The following conclusions were reached: (1) The heterodyne beat method can be applied successfully to the measurement of dielectric constants of gases at frequencies up to 56 megacycles per second. (2) The dielectric constant of gaseous nitrogen, carbon dioxide and ammonia are the same at 56 megacycles per second as at lower frequencies. (3) The absolute values of the dielectric constants of ...


Effect Of Quartz Filters On The Distribution Of Energy In Laue Patterns , Dean Waldo Stebbins Jan 1938

Effect Of Quartz Filters On The Distribution Of Energy In Laue Patterns , Dean Waldo Stebbins

Retrospective Theses and Dissertations

An experiment was carried out using a double crystal setup to try to determine the amount of energy diffracted by the perfect portion of the crystal and to try to determine the effect of oscillation on the Intensity of the central beam. The effect of oscillating the crystal at its third harmonic was also investigated. The effect of temperature on the intensity of Laue spots from oscillating crystals was also studied. From this investigation the following conclusions are drawn: (1) the amount of energy of a particular wavelength reflected by the "perfect" portion of a crystal is very small compared ...


Breakdown Potentials Of Gases Under Alternating Voltages , David Oren Mccoy Jan 1938

Breakdown Potentials Of Gases Under Alternating Voltages , David Oren Mccoy

Retrospective Theses and Dissertations

This investigation was devoted to a study of the starting potentials of gases of commercial purity for frequencies less than one million cycles per second. The gases used were Hydrogen, Nitrogen, Helium, and Argon. The discharge tube was of spherical design having spherical aluminum electrodes three-fourths inch to diameter. Five gap distances were used ranging from 10 mm to 50 mm;The results of the investigation show that: (1) The effect of impurities in the gas pointed out by J. Thomson were not observed. (2) The usual straight line portion of the curves of Vs versus pressure were observed to ...


High Frequency Glow Discharge With Internal Electrodes , Nathan Theodore Burdine Jan 1937

High Frequency Glow Discharge With Internal Electrodes , Nathan Theodore Burdine

Retrospective Theses and Dissertations

This thesis was a quantitative study of the variation in intensities of certain lines in the hydrogen spectrum as a function of excitation frequency and pressure when internal electrodes were used. The high frequency voltage was applied to the gas by the connection of a push-pull oscillator to internal carbon electrodes. The gas system was designed to obtain spectroscopically pure hydrogen. The logarithmic sector method was used to measure the intensities of the spectrum lines, and a cathode ray oscillograph was used to measure the potential difference between the electrodes;The spectrograms were taken for pressures ranging from .005 to ...


The Effect Of A Gas Film On Metal Surfaces Used For Electron Recording , Morton Alden Countryman Jan 1936

The Effect Of A Gas Film On Metal Surfaces Used For Electron Recording , Morton Alden Countryman

Retrospective Theses and Dissertations

A platinum strip was exposed to electron beams of moderate velocity, and then exposed in situ to development by mercury vapour from a mall amount of mercury always present in the tube but cooled by a refrigerant during electron exposures. The system contained no grease or wax seals and the tube containing the platinum strip and electron gun was submerged during exposure in a refrigerant (CO2 in acetone). The platinum strip was so arranged that it could be heated by passing an electric current through it;A definite electron record secured under the following conditions: (a) If there was present ...


A Study Of The Piezo-Electric Oscillations Of Quartz Plates , Robert Granzow Wilson Jan 1936

A Study Of The Piezo-Electric Oscillations Of Quartz Plates , Robert Granzow Wilson

Retrospective Theses and Dissertations

An investigation was carried out to determine as completely as possible the behavior of a quartz plate vibrating piezo-electrically in modes depending on the thickness. Solutions of the equations of motion were derived and numerical results were obtained giving the resonance frequencies to be expected for any orientation of the plate with respect to the natural axes of quartz crystals;Studies of various edge effects were carried out to prove points predicted by the theory;The filter method of frequency measurement was used in determining the resonance frequencies of the experimental plates.


X-Ray Extinction In Piezo Electric Crystals , Walter Alexander Fraser Jan 1935

X-Ray Extinction In Piezo Electric Crystals , Walter Alexander Fraser

Retrospective Theses and Dissertations

The extent to which x-ray extinction occurs in a crystal is determined by the perfection of the crystal. Those wavelengths which could be reflected by the lattice in a perfect crystal are extinguished by multiple reflections, resulting in a high absorption coefficient for the crystal. The imperfection of the surface decreases the possible number of these multiple reflections, thereby increasing the energy going to form the Laue patterns;Piezo electric oscillation of quartz, Rochelle salt and tourmaline crystals brings about as increase in the intensity of the Laue pattern formed by the reflection of x-rays passing the crystals. This effect ...


Blackening Of Photographic Materials By Means Of Low Voltage Cathode Rays , Allan Reedy Brown Jan 1935

Blackening Of Photographic Materials By Means Of Low Voltage Cathode Rays , Allan Reedy Brown

Retrospective Theses and Dissertations

Work undertaken was to determine the effect of cathode rays photographic materials. It was desired to find the relations between the voltage of the cathode rays and blackening, and the total charge received by the film and the blackening;Special apparatus was designed for carrying out this work, exposures being made a specially constructed vacuum chamber of brass. The apparatus differed from apparatus previously used for this type of work in that a special camera was provided which made exposures on a film moving past a slit through which the electrons entered the camera. The slit was half v-shaped, giving ...


Recording Of Low Voltage Cathode Rays On Metal Films , Joseph Bion Philipson Jan 1933

Recording Of Low Voltage Cathode Rays On Metal Films , Joseph Bion Philipson

Retrospective Theses and Dissertations

No abstract provided.