Engineering Physics Commons^™

Determination Of (N, 2n) Reaction Cross-Sections For 71ga, 106cd & 138ba Using 14 Mev Neutrons, Thomas Helm

Masters Theses & Specialist Projects

The increasing trend towards the use of activation analysis as an analytic means of identifying elements and determining their relative abundance demands more accurate values of reaction cross-sections. Accurate values of cross-sections are also important in the investigation of possible shell effects in reaction mechanisms. Many activation cross-sections for reactions produced by 14 MeV neutrons have been measured because of the relative ease with which this energy of neutrons can be produced. Low voltage accelerators are capable of producing 14. MeV neutrons by the ³H( d,n)⁴He reaction. Although many people^(1-5) have measured the (n,2n) reaction cross-sections …

An Experimental And Theoretical Study Of The Nucleation Of Water Vapor On Ions In Helium And Argon, Daniel R. White

Doctoral Dissertations

"The nucleation of water vapor on ions in atmospheres of helium and argon was studied using an expansion type cloud chamber. Separation of the positive and negative ions was achieved so that the nucleation could be studied as a function of both the sign of the ionic charge and the supersaturation. A semiphenominological theory was developed as an extension of the classical theory to include the effects of the ionic charge on the nucleation process. The theoretical model of the prenucleation embryo was assumed to possess an oriented dipole surface layer with the direction of orientation dependent on the sign …

A Nonsecond Time-Of-Flight Spectometer, David Moorman

Masters Theses & Specialist Projects

The purpose of this thesis was to construct a time-of-flight spectrometer using plastic scintillators coupled to photomultiplier tubes as the primary detectors. A time-of-flight spectrometer with at least 2.0 nanoseconds of time resolution was desired.

Electrical Conductivity & Seebeck Effect In Activated Molybdenum Oxide Hydrogen Detectors, John Hooker

Masters Theses & Specialist Projects

This thesis describes the results and analysis of Seebeck coefficient and electrical conductivity measurements on "activated", molybdenum-oxide, thin film hydrogensensing elements. The work was undertaken in an effort to produce data that would be useful in obtaining an understanding of the electronic processes which cause large electrical conductivity changes in molybdenum-oxide upon exposure to small concentrations of hydrogen in air. The results are analyzed using a simple band model of a semiconductor. This model is shown to give reasonable results at high temperatures; however, a departure from the usual .! model is required in order to explain the results at …

Crossed Field Trochoidal Trajectory Devices For Investigating The Reflection Of Slow Electrons From Metallic Surfaces, Stan Lemaster

Masters Theses & Specialist Projects

The objective of this study was to build preliminary devices . which could be used to measure electron reflection coefficient values using crossed electric and magnetic fields. The technique for using crossed fields to measure reflection coefficients was developed at Air Force Cambridge Research Laboratories. The reflection coefficient is the ratio of the number of electrons in a reflected beam to the number of electrons in an incident beam striking a surface.

The work described herein was a part of a project authored by AFCRL under contract AF19 (628)-5940; Project 8605 (with Western Kentucky University being the contractor) which was …

Solid State Electrolysis Of Yttria Stablized Zirconia, John Newman

Masters Theses & Specialist Projects

Zirconium dioxide, or zirconia, is seemingly an ideal refractory oxide, having a high melting point (2680°C), low thermal expansion and also a considerable resistance to most forms of chemical attack. Early researchers soon found that zirconia, in the pure form, was actually of very limited use as a refractory because of sudden and disruptive volume changes accompanying a change in crystal structure which occurs at a temperature of about 1100 o C. It was discovered that this crystal structure change could be suppressed by the addition of one of a number of alkaline earth or rare earth oxides. These additive …

Environmental Effects On The Resistivity Of Palladium-Silver Alloy Films In High Vacuum, Frank Snyder

Masters Theses & Specialist Projects

The reported usage of the palladium-silver alloy films as resistors in the electronics industry has been in encapsulated form. By mounting the resistor inside vacuum electron devices, there is the possibility of eliminating the encapsulation. A literature search has revealed no reported efforts of experiments with unencapsulated resistors and certainly no reports of the palladium-silver alloy resistor in vacuum tubes or other high vacuum environments. Therefore, the research reported in this thesis will concentrate on the environmental effects on resistivity of palladium-silver alloy films in high vacuum.

Epr Spectra Of Divalent Manganese In Halide Crystals, Veron Sarkis Sarkissian

Archived Theses and Dissertations

No abstract provided.

Conductivity And Photoconductivity Of As-S-I Glasses, Ahmed Abdel-Hamid El-Difrawi

Archived Theses and Dissertations

No abstract provided.

The Relative Influence Of Raw Material Components Upon The Thermal Expansion Of Vitreous Enamel., Robert C. Boyd

Electronic Theses and Dissertations

No abstract provided.

Material For An Autobiography [Excerpt], 1927, Robert H. Goddard

March 16, 1926: The First Liquid-Propellant Rocket Launch

An excerpt from 'Material for an Autobiography', written by Robert Goddard in 1927 with some interpolations made in 1933. This writing never materialized into a full autobiography but can be read in The Papers of Robert H. Goddard, Volume I: [1927 and 1933: Material for an Autobiography]. This is an excerpt from that material, which covers the landmark March 16, 1926 rocket launch as well as the months between December 1925 and March 16. Goddard includes excerpts from his diary. Goddard's full diary entries from March 16 and 17, 1926 have been made available as their own excerpt here, …

Robert Goddard's Diary Entry, March 17, 1926, Robert H. Goddard

March 16, 1926: The First Liquid-Propellant Rocket Launch

Robert Goddard's entry for March 17, 1926, from a newly digitized scan of Goddard's 1926 diary. This entry covers the events of the previous day, March 16, in which he achieved the world's first liquid-fuel rocket launch. Goddard kept one diary for each year, from 1898 until his death in 1945.

This entry is included towards the back of the diary, in the 'Memoranda' section, in order to have the space to fit his recounting of the day. The diary was a daily one and only left a few lines for each day. The transcription is as follows:

"The …

Robert Goddard's 1926 Diary, Robert H. Goddard

March 16, 1926: The First Liquid-Propellant Rocket Launch

A newly digitized scan of Robert Goddard's 1926 diary, the year he achieved the world's first liquid-fuel rocket launch. Goddard kept one diary for each year, from 1898 until his death in 1945. Transcriptions of key dates can be found in the section of The Papers of Robert H. Goddard titled '1925-1930: Liquid Propellant Rockets Fly'.

Please note that this is a daily diary, which only leaves a few lines to write about each day. Goddard wrote at more length about March 16th on March 17th but wrote that extra writing in a 'Memoranda' section towards the end of …

Figure 102: Two Tanks For Pressure-Operated Rocket, Winter 1926, Esther C. Goddard

March 16, 1926: The First Liquid-Propellant Rocket Launch

Photograph of two tanks for a pressure-operated rocket. The tank on the right would hold liquid oxygen that created pressure once vaporized (a disassembled view can be seen in Figure 103), and the smaller gasoline tank is on the left. These tanks would be modified in several ways leading up to the March 16, 1926 launch. Photographs of the subsequent tanks can be found in Figure 109, 110, 111, 112, 113, 114, and 115.

These were the first pressure tanks made following December 6, 1925 (the day Robert Goddard achieved the first …

Development Of A Liquid Propelled Rocket, Section Iii: December 1925 - May 1926 [Excerpt], Robert H. Goddard

March 16, 1926: The First Liquid-Propellant Rocket Launch

Excerpt from a report written by Robert Goddard tracing his development of the first liquid-propelled rocket. The full report covers 1921 to 1929. This excerpt contains most of part three which covers everything following December 6, 1925 (the day Robert Goddard achieved the first liquid-fuel rocket to lift its own weight) and May 1926. This excerpt contains everything up through March 16, 1926, the day Goddard saw the world's first successful launch of a liquid-propelled rocket.

The December 6, 1925 test used the pumps, engines, and other moving parts Goddard spent years working with and developing. Following this test, Goddard …

An Experimental Study Of The Cathode Fall In Helium And Argon With Wire Cathodes, L. G. Raub

University Studies (University of Nebraska) (1888–1984)

It was recognized rather early in the study of the phenomena of discharge of electricity through gases that the ordinary laws of conduction as found in solid and liquid conductors are not applicable to gases. It was shown by Zeleny and independently by Child that Ohm's law by no means represents the distribution of potential between electrodes in an ionized gas, but that the potential gradient is large in the vicinity of the electrodes, and not uniform throughout the space between them. When the pressure of the gas surrounding the electrodes is reduced to one or two millimeters and a …