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Full-Text Articles in Physics

Chromatic Aberration Of Eyepieces In Early Telescopes, M. Eugene Rudd Jan 2007

Chromatic Aberration Of Eyepieces In Early Telescopes, M. Eugene Rudd

M. Eugene Rudd Publications

The twofold objective of this study is (1) to identify and give a brief review of the historical development of the various designs of early (pre-1850) telescope eyepieces, and (2) to determine by measurements and calculations the axial and lateral chromatic aberrations of a number of extant eyepieces from that period in order to provide basic data on which to judge the relative quality of different eyepiece forms. Eight distinct types of eyepieces containing one to five lens elements are discussed and illustrated. The second objective was addressed by measuring the focal lengths of the individual lens elements and the ...


Apparatus For Studying Wave Motion And Sound At The University Of Nebraska– Lincoln's “Historical Scientific Instrument Gallery”, Lily M. Wang, M. Eugene Rudd Jan 2004

Apparatus For Studying Wave Motion And Sound At The University Of Nebraska– Lincoln's “Historical Scientific Instrument Gallery”, Lily M. Wang, M. Eugene Rudd

M. Eugene Rudd Publications

The University of Nebraska–Lincoln's “Historical Scientific Instrument Gallery,'' compiled by the second author in 1998, contains approximately 700 inventoried items and may be visited on-line at http://physics.unl.edu/outreach/histinstr/. Amidst the collection are several acoustical instruments that were used in the early 1900s. These include equipment that demonstrate wave motion (traveling wave machine, mercury ripple dish, vibration microscope), wave interference (interference machine), resonance conditions (Helmholtz resonators, vibrating rods, singing flames, sonometer), and sound generation (Galton's whistles, high-frequency tuning forks, large tuning forks, organ pipes, siren saw). A review of the equipment and the history ...


Two-Center Effect On Low-Energy Electron Emission In Collisions Of 1-Mev/U Bare Ions With Atomic Hydrogen, Molecular Hydrogen, And Helium: Ii. H2 And He, Lokesh C. Tribedi, P. Richard, L. Gulya´S, M. Eugene Rudd Jan 2001

Two-Center Effect On Low-Energy Electron Emission In Collisions Of 1-Mev/U Bare Ions With Atomic Hydrogen, Molecular Hydrogen, And Helium: Ii. H2 And He, Lokesh C. Tribedi, P. Richard, L. Gulya´S, M. Eugene Rudd

M. Eugene Rudd Publications

We have studied the energy and angular distributions of low-energy electron emission in collisions of bare carbon ions of 1-MeV/u energy with He and H2 targets. The double-differential cross sections (DDCS’s) are measured for electrons with energies between 0.5 and 300 eV emitted within an angular range of 15° to 160°. The large forward-backward asymmetry observed in the angular distributions is explained in terms of the two-center effect. Single differential cross sections (SDCS’s) and total cross sections are also derived by integrating the DDCS’s over emission angles and energies. The data are compared with ...


Two-Center Effect On Low-Energy Electron Emission In Collisions Of 1-Mev/U Bare Ions With Atomic Hydrogen, Molecular Hydrogen, And Helium. I. Atomic Hydrogen, Lokesh C. Tribedi, P. Richard, L. Gulya´S, M. Eugene Rudd, R. Moshammer Jan 2001

Two-Center Effect On Low-Energy Electron Emission In Collisions Of 1-Mev/U Bare Ions With Atomic Hydrogen, Molecular Hydrogen, And Helium. I. Atomic Hydrogen, Lokesh C. Tribedi, P. Richard, L. Gulya´S, M. Eugene Rudd, R. Moshammer

M. Eugene Rudd Publications

We have investigated ionization mechanisms in fast ion-atom collisions by measuring the low-energy electron emission cross sections in a pure three-body collision involving bare carbon ions (v=6.35 a.u.) colliding with atomic hydrogen targets. The measurements have also been extended to molecular hydrogen and helium targets. In this paper we provide the energy and angular distributions of double differential cross sections of low-energy electron emission for atomic hydrogen targets. The Slevin rf source with a high degree of dissociation was used to produce the atomic H target. It is found that the two-center effect has a major influence ...


Cross Sections For Singly Differential And Total Ionization Of Helium By Electron Impact, Yong-Ki Kim, Walter R. Johnson, M. Eugene Rudd Jan 2000

Cross Sections For Singly Differential And Total Ionization Of Helium By Electron Impact, Yong-Ki Kim, Walter R. Johnson, M. Eugene Rudd

M. Eugene Rudd Publications

The binary-encounter dipole (BED) model for electron-impact ionization is applied to helium using the continuum dipole oscillator strength calculated from the relativistic random-phase approximation. The resulting total ionization cross section agrees with available experimental data well within the quoted experimental uncertainties. The singly differential (=energy distribution of ejected electrons) cross section agrees well in shape with available experiments. Because of the remarkable agreement with experiment at all incident and ejected electron energies and the compact analytic form of the cross sections, we propose that the BED cross sections for helium serve as a normalization standard with an accuracy of ±5 ...


Ionization Dynamics In Fast Ion-Atom Collisions. I. Energy And Angular Distributions Of Low-Energy Electrons Emitted In Ionization Of He By Bare Carbon Ions, Lokesh C. Tribedi, P. Richard, Y. D. Wang, C. D. Lin, L. Gulyas, M. Eugene Rudd Nov 1998

Ionization Dynamics In Fast Ion-Atom Collisions. I. Energy And Angular Distributions Of Low-Energy Electrons Emitted In Ionization Of He By Bare Carbon Ions, Lokesh C. Tribedi, P. Richard, Y. D. Wang, C. D. Lin, L. Gulyas, M. Eugene Rudd

M. Eugene Rudd Publications

We have studied the two-center effect (TCE) in ion-atom ionization by measuring the energy and angular distributions of the double-differential cross sections (DDCSs) (d2σ/dεdΩ) of the low-energy electrons emitted in a collision of He atoms with 2.5 MeV/nucleon C6+ ions. The electrons with energies between 0.1 and 300 eV were detected for 13 different emission angles between 15° and 160°. From the measured DDCSs we have deduced the single differential cross sections such as dσ/dΩ and dσ/dε and the total cross section. The data ...


Electron-Impact Total Ionization Cross Sections Of Ch And C2H2, Yong-Ki Kim, M. Asgar Ali, M. Eugene Rudd Dec 1997

Electron-Impact Total Ionization Cross Sections Of Ch And C2H2, Yong-Ki Kim, M. Asgar Ali, M. Eugene Rudd

M. Eugene Rudd Publications

Electron-impact total ionization cross sections for the CH radical and C2H2 (acetylene) have been calculated using the Binary-Encounter-Bethe (BEB) model. The BEB model combines the Mott cross section and the asymptotic form of the Bethe theory, and has been shown to generate reliable ionization cross sections for a large variety of molecules. The BEB cross sections for CH and C2H2 are in good agreement with the available experimental data from ionization thresholds to hundreds of eV in incident energies.


Shielding Strategies For Human Space Exploration Chapter 9: Hze Interactions In Biological Materials, M. Eugene Rudd Dec 1997

Shielding Strategies For Human Space Exploration Chapter 9: Hze Interactions In Biological Materials, M. Eugene Rudd

M. Eugene Rudd Publications

It is shown that most of the energy deposited by fast charged particles traversing matter occurs through ionization, i.e., the ejection of electrons during the atomic collision. The important mechanisms of ionization are identified and several methods of calculating the relevant differential and total cross sections are described. These include both classical and quantum theoretical methods and two semi-empirical models. The calculational methods were intended only for light, bare-ion projectiles, and care must be exercised in extending them to heavy, dressed projectiles.


Spurious Electrons In Electron Spectrometers And Their Effect On Differential Electron Impact Ionization Cross-Section Measurements, M. Eugene Rudd Aug 1997

Spurious Electrons In Electron Spectrometers And Their Effect On Differential Electron Impact Ionization Cross-Section Measurements, M. Eugene Rudd

M. Eugene Rudd Publications

The effect of the nonideal response characteristics of electrostatic analyzers is described and equations are derived, which allow a calculation of the distortion that this causes in measurements of angular and energy distributions of electrons from atomic collisions, especially in electron impact. Examples are given that show how a contamination as small as 10-5 from spurious electrons generated inside an analyzer can explain the peak seen at zero angle in some angular distribution measurements and the filling in of the minimum in the energy distributions in others.


Electron-Impact Ionization Cross Sections Of Atmospheric Molecules, Y.-K. Kim, W. Hwang, N. M. Weinberger, M. A. Ali, M. Eugene Rudd Jan 1997

Electron-Impact Ionization Cross Sections Of Atmospheric Molecules, Y.-K. Kim, W. Hwang, N. M. Weinberger, M. A. Ali, M. Eugene Rudd

M. Eugene Rudd Publications

A theoretical model for electron-impact total ionization cross sections, which has been found to be reliable for a wide range of molecules, is applied to molecules of interest to atmospheric science. The new theory, the binary-encounter-Bethe (BEB) model, combines the binary encounter theory and the Bethe theory for electron-impact ionization, and uses simple theoretical data for the ground state of the target molecule, which are readily available from molecular structure codes. Total ionization cross sections of 11 molecules, CS, CS2, COS, CH4, H2S, NH3, NO2, N2O, O3, S2, and SO ...


Electron-Impact Total Ionization Cross Sections Of Silicon And Germanium Hydrides, M. A. Ali, Y.-K. Kim, W. Hwang, N. M. Weinberger, M. Eugene Rudd Jan 1997

Electron-Impact Total Ionization Cross Sections Of Silicon And Germanium Hydrides, M. A. Ali, Y.-K. Kim, W. Hwang, N. M. Weinberger, M. Eugene Rudd

M. Eugene Rudd Publications

Electron-impact total ionization cross sections of some silicon and germanium compounds have been calculated by applying a new theoretical model that has been found to be reliable for a wide range of molecules. The new theory, the binary-encounter-Bethe (BEB) model, combines the binary-encounter theory and the Bethe theory for electron-impact ionization, and uses simple theoretical molecular orbital data—binding energies, average kinetic energies, and occupation numbers—which are readily available from molecular structure codes. Total ionization cross sections of SiH, SiH2, SiH3, SiH4, Si2H6, Si(CH3)4, GeH, GeH2, GeH3, GeH ...


Electron Energy Distributions From Multiple Ionization In 20–120-Kev H+ + Ar Collisions, Yang-Soo Chung, M. Eugene Rudd Nov 1996

Electron Energy Distributions From Multiple Ionization In 20–120-Kev H+ + Ar Collisions, Yang-Soo Chung, M. Eugene Rudd

M. Eugene Rudd Publications

Energy-analyzed secondary electrons from H+ + Ar collisions at eight proton energies from 20 to 120 keV were detected in coincidence with recoil ions of charge states 1–3. The charge states were distinguished by time-of-flight measurements and the electron energies were analyzed by a newly designed electrostatic analyzer of the low-pass high-pass filter type which has a large (~1.45π steradian) solid angle acceptance. For each of nine electron energies from 10 to 160 eV, the ionizing events associated with each residual ion charge state were counted. The electron energy dependence of the charge-state ratios and the average charge determined ...


Doubly Differential Cross Sections Of Low-Energy Electrons Emitted In The Ionization Of Molecular Hydrogen By Bare Carbon Ions, Lokesh C. Tribedi, P. Richard, D. Ling, Y. D. Wang, C. D. Lin, R. Moshammer, G. W. Kerby Iii, M. W. Gealy, M. Eugene Rudd Sep 1996

Doubly Differential Cross Sections Of Low-Energy Electrons Emitted In The Ionization Of Molecular Hydrogen By Bare Carbon Ions, Lokesh C. Tribedi, P. Richard, D. Ling, Y. D. Wang, C. D. Lin, R. Moshammer, G. W. Kerby Iii, M. W. Gealy, M. Eugene Rudd

M. Eugene Rudd Publications

We have measured the double differential cross sections (DDCS) (d2σ/dεedΩe) of low-energy electron emission in the ionization of H2 bombarded by bare carbon ions of energy 30 MeV. The energy and angular distributions of the electron DDCS have been obtained for 12 different emission angles and for electron energies varying between 0.1 and 300 eV. We have also deduced the single differential and total ionization cross section from the measured DDCS. The data have been compared with the predictions of first Born approximations and the CDW-EIS (continuum distorted wave–eikonal ...


The Observatory That Never Was, M. Eugene Rudd May 1996

The Observatory That Never Was, M. Eugene Rudd

M. Eugene Rudd Publications

Astronomy has been taught at the University of Nebraska since it first opened its doors in 1871, but for almost half of this time the university had no telescope larger than a Cinch Brashear refractor. Goodwin DeLoss Swezey, the astronomy professor at the turn of the century, had a small observatory built on campus to house this and other astronomical instruments.
Despite Swezey's ambitions for a larger telescope, the university's resources were limited. So he proposed to build a 12-inch refractor himself with the help of Charles S. Minnich, a nearby country doctor and amateur astronomer. Not only ...


New Model For Electron-Impact Ionization Cross Sections Of Molecules, W. Hwang, Y.-K. Kim, M. Eugene Rudd Feb 1996

New Model For Electron-Impact Ionization Cross Sections Of Molecules, W. Hwang, Y.-K. Kim, M. Eugene Rudd

M. Eugene Rudd Publications

A theoretical model for electron-impact ionization cross sections, which has been developed primarily for atoms and atomic ions, is applied to neutral molecules. The new model combines the binary-encounter theory and the Bethe theory for electron-impact ionization, and uses minimal theoretical data for the ground state of the target molecule, which are readily available from public-domain molecular structure codes such as GAMESS. The theory is called the binary encounter Bethe (BEB) model, and does not, in principle, involve any adjustable parameters. Applications to 19 molecules, including H2, NO, CH2, C6H6, and SF6, are presented ...


Energy And Angular Distributions Of Electrons From Ion Impact On Atomic And Molecular Hydrogen. Iii. 28–114-Kev He+ + H2, Y.-Y. Hsu, M. W. Gealy, G. W. Kerby Iii, M. Eugene Rudd Jan 1996

Energy And Angular Distributions Of Electrons From Ion Impact On Atomic And Molecular Hydrogen. Iii. 28–114-Kev He+ + H2, Y.-Y. Hsu, M. W. Gealy, G. W. Kerby Iii, M. Eugene Rudd

M. Eugene Rudd Publications

Absolute cross sections, differential in energy and angle of ejection of the secondary electrons, were determined for electron emission from He+ +H2 collisions at 28–114 keV by measuring electron energy spectra from 1.5 to 300 eV at several angles from 15° to 160°. A rotatable electrostatic analyzer was used with an energy resolution of 5% and an angular acceptance of 4.6° full width at half maximum. The double-differential cross sections were integrated over angle, energy, or both to obtain single-differential and total ionization cross sections. The latter are in excellent agreement with previous experimental results. Agreement ...


Energy And Angular Distributions Of Electrons From Ion Impact On Atomic And Molecular Hydrogen. Iv. 28–114-Kev He+ + H Collisions, Y.-Y. Hsu, M. W. Gealy, G. W. Kerby Iii, M. Eugene Rudd, D. R. Schultz, C. O. Reinhold Jan 1996

Energy And Angular Distributions Of Electrons From Ion Impact On Atomic And Molecular Hydrogen. Iv. 28–114-Kev He+ + H Collisions, Y.-Y. Hsu, M. W. Gealy, G. W. Kerby Iii, M. Eugene Rudd, D. R. Schultz, C. O. Reinhold

M. Eugene Rudd Publications

Absolute ionization cross sections for 28–114-keV helium ion impact on atomic hydrogen, differential in energy and angle of the ejected electrons, have been obtained from crossed-beam measurements and previously measured cross sections for molecular hydrogen targets. A radio frequency discharge source produced a mixed atomic and molecular target with a typical dissociation fraction of 74%. Energy spectra were measured from 1.5 to 130 eV by an electrostatic analyzer with a resolution of 5%. The angular range was 15° –160°. Results are compared with calculations based on the first Born, continuum-distorted-wave–eikonal-initial-state, and classical trajectory Monte Carlo methods. Total ...


Energy And Angular Distributions Of Electrons From Ion Impact On Atomic And Molecular Hydrogen. I. 20- 114-Kev H+ + H2, M. W. Gealy, G. W. Kerby, Iii, Y.-Y. Hsu, M. Eugene Rudd Mar 1995

Energy And Angular Distributions Of Electrons From Ion Impact On Atomic And Molecular Hydrogen. I. 20- 114-Kev H+ + H2, M. W. Gealy, G. W. Kerby, Iii, Y.-Y. Hsu, M. Eugene Rudd

M. Eugene Rudd Publications

Apparatus and procedures are described for the measurement of absolute cross sections, differential in ejected electron energy and angle, for ionization of atomic and molecular hydrogen by ion impact. A hemispherical electrostatic energy analyzer, rotatable from 15° to 165° with respect to the direction of the incident ion beam, was used to measure energy spectra of secondary electrons from 1.5 to 300 eV. Cross sections at ten angles (nine at some energies) and five incident-ion energies from 20 to 114 keV for H+ +H2 collisions are given. The doubly differential cross sections were integrated over angle and electron ...


Energy And Angular Distributions Of Electrons From Ion Impact On Atomic And Molecular Hydrogen. Ii. 20- 114-Kev H+ + H, G. W. Kerby, Iii, M. W. Gealy, Y.-Y. Hsu, M. Eugene Rudd, D. R. Schultz, C. O. Reinhold Mar 1995

Energy And Angular Distributions Of Electrons From Ion Impact On Atomic And Molecular Hydrogen. Ii. 20- 114-Kev H+ + H, G. W. Kerby, Iii, M. W. Gealy, Y.-Y. Hsu, M. Eugene Rudd, D. R. Schultz, C. O. Reinhold

M. Eugene Rudd Publications

Results of crossed-beam measurements of cross sections differential in ejected electron energy and angle for ionization of atomic hydrogen by 20-1 14-keV protons are reported. Secondary electrons were measured over an energy range of 1.5-300 eV and an angular range of 15°-165°. Atomic-hydrogen targets were produced in a radio-frequency discharge source with a dissociation fraction of about 74%. Ratios of cross sections for H targets to those for Hz targets were obtained from measurements on the mixed target. From these ratios, the measured dissociation fractions, and the absolute cross sections measured for H, targets, the cross sections for ...


Binary-Encounter-Dipole Model For Electron-Impact Ionization, Yong-Ki Kim, M. Eugene Rudd Nov 1994

Binary-Encounter-Dipole Model For Electron-Impact Ionization, Yong-Ki Kim, M. Eugene Rudd

M. Eugene Rudd Publications

A theoretical model, which is free of adjustable or fitted parameters, for calculating electron impact ionization cross sections for atoms and molecules is presented. This model combines the binary-encounter theory with the dipole interaction of the Bethe theory for fast incident electrons. The ratios of the contributions from distant and close collisions and interference between the direct and exchange terms are determined by using the asymptotic behaviors predicted by the Bethe theory for ionization and for stopping cross sections. Our model prescribes procedures to calculate the singly differential cross section (energy distribution) for each subshell using the binding energy, average ...


Doubly Differential Electron-Production Cross Sections For 200- 1500-Ev E- +H2 Collisions, M. Eugene Rudd, K. W. Hollman, J. K. Lewis, D. L. Johnson, R. R. Porter, E. L. Fagerquist Mar 1993

Doubly Differential Electron-Production Cross Sections For 200- 1500-Ev E- +H2 Collisions, M. Eugene Rudd, K. W. Hollman, J. K. Lewis, D. L. Johnson, R. R. Porter, E. L. Fagerquist

M. Eugene Rudd Publications

Ionization cross sections differential in the angle and energy of the detected electrons were measured for electron impact on hydrogen gas at 200, 500, 1000, and 1500 eV. Measurements were made from 15°-150° and from a few eV to T -I where T is the primary electron energy and I the ionization potential of hydrogen. The results are compared to earlier measurements and to available calculations.


Backward Peak In The Electron Spectrum From Collisions Of 70-Kev Protons With A Target From A Hydrogen-Atom Source, M. Eugene Rudd, M. W. Gealy, G. W. Kerby, Iii, Ying-Yuan Hsu Mar 1992

Backward Peak In The Electron Spectrum From Collisions Of 70-Kev Protons With A Target From A Hydrogen-Atom Source, M. Eugene Rudd, M. W. Gealy, G. W. Kerby, Iii, Ying-Yuan Hsu

M. Eugene Rudd Publications

A large, broad peak has been found in the electron energy spectrum from 30 to 100-keV H+ + H collisions. The peak, which is centered at 31 eV, appears only in the backward directions. It is suggested that while the peak is unlikely to come from collisions with atoms in the ground or metastable states, it could arise from collisions with atoms in highly excited states or from autoionizing states of the residual H2 in the target.


Science On The Great Plains: The History Of Physics And Astronomy At The University Of Nebraska-Lincoln, M. Eugene Rudd Jan 1992

Science On The Great Plains: The History Of Physics And Astronomy At The University Of Nebraska-Lincoln, M. Eugene Rudd

M. Eugene Rudd Publications

The year 1988 marked the 100th anniversary of the founding of the Department of Physics at the University of Nebraska. While the year passed without fanfare in the department, DuaneJaecks, one of the members of the faculty, suggested to the author that it would be a good time to write a history of what is now the Department of Physics and Astronomy. He not only provided the initial impetus for the project, but has also given it his continual help and encouragement. While the initial plan was to write only a brief, informal departmental history, the project, like Topsy, grew ...


Differential And Total Cross Sections For Ionization Of Helium And Hydrogen By Electrons, M. Eugene Rudd Aug 1991

Differential And Total Cross Sections For Ionization Of Helium And Hydrogen By Electrons, M. Eugene Rudd

M. Eugene Rudd Publications

A comprehensive semiempirical model for singly and doubly differential and total ionization cross sections for electron production by electron impact is presented. The model is discussed in relation to several theoretically required constraints. Available experimental data for hydrogen and helium targets are examined, and recommended values of the data are given for all ranges of primary and secondary energies and angles of ejection.


Recoil Ions From Near-Zero-Impact-Parameter H+-Xe Collisions In The Range 20- 70 Kev, Wen-Qin Cheng, M. Eugene Rudd May 1991

Recoil Ions From Near-Zero-Impact-Parameter H+-Xe Collisions In The Range 20- 70 Kev, Wen-Qin Cheng, M. Eugene Rudd

M. Eugene Rudd Publications

Recoil ions from very small impact-parameter collisions of 20-70-keV protons with xenon atoms were selected by viewing only those ejected at 50° and 70° from the beam direction. These ions were charge-state analyzed and the cross sections determined for the production of charge states up to 6+. In such collisions, multiple ionization accounts for 60-80% of the ionizing collisions and 80-90 % of the total ionization.


Angular And Energy Distributions Of Electrons From 7.5- 150-Kev Proton Collisions With Oxygen And Carbon Dioxide, Wen-Qin Cheng, M. Eugene Rudd, Ying-Yuan Hsu Oct 1989

Angular And Energy Distributions Of Electrons From 7.5- 150-Kev Proton Collisions With Oxygen And Carbon Dioxide, Wen-Qin Cheng, M. Eugene Rudd, Ying-Yuan Hsu

M. Eugene Rudd Publications

Cross sections for the ejection of electrons, differential in the angle and energy of emission, were measured for proton collisions with two molecular gases, oxygen and carbon dioxide, over the primary energy range of 7.5-150 keV and an angular range of 10° to 160°. The energy distributions, obtained by integration over the angle, were fitted by an analytical model. A discrepancy in the angular distributions compared to those of Gibson and Reid [J. Phys. E 17, 1227 (1984); J. Phys. B 19, 3265 (1986); Radiat. Res. 112, 418 (1987); Australian Atomic Energy Commission Report No. AAEC/E659, 1987 (unpublished ...


Differential Cross Sections For Ejection Of Electrons From Rare Gases By 7.5- 150-Kev Protons, Wen-Qin Cheng, M. Eugene Rudd, Ying-Yuan Hsu Mar 1989

Differential Cross Sections For Ejection Of Electrons From Rare Gases By 7.5- 150-Kev Protons, Wen-Qin Cheng, M. Eugene Rudd, Ying-Yuan Hsu

M. Eugene Rudd Publications

Absolute cross sections for the ejection of electrons by ;proton impact that are differential in the angle and energy of the electrons have been measured for :helium, neon, and krypton. The primary energy ranged from 7.5 to 150 keV, the angles from 10° to 160°, and the measured energies from 1 to 550 eV. These data along with earlier data on argon are used to study the systematics of proton impact ionization of the rare gases. An analytical model is employed to correlate and systematize the cross-section differential in ejected-electron energy. For low-energy collisions the angular distribution of electrons ...


User-Friendly Model For The Energy Distribution Of Electrons From Proton Or Electron Collisions, M. Eugene Rudd Jan 1989

User-Friendly Model For The Energy Distribution Of Electrons From Proton Or Electron Collisions, M. Eugene Rudd

M. Eugene Rudd Publications

A model is presented which gives cross sections (differential in the ejected secondary electron energy) for the ionization of atoms and molecules in proton or electron collisions. The model is in the form of an analytical equation which holds for all primary and secondary energies and for any target gas for which certain parameters are known. The accuracy is estimated to be 15-20%. The model is based on the classical binary encounter model modified to agree with the Bethe theory at high energies and, for proton impact, with the molecular promotion model at low energies. For multi-shell targets, the partial ...


Differential Cross Sections For Secondary Electron Production By 1.5-Kev Electrons In Water Vapor, K. W. Hollman, G. W. Kerby, Iii, M. Eugene Rudd, J. H. Miller, S. T. Manson Oct 1988

Differential Cross Sections For Secondary Electron Production By 1.5-Kev Electrons In Water Vapor, K. W. Hollman, G. W. Kerby, Iii, M. Eugene Rudd, J. H. Miller, S. T. Manson

M. Eugene Rudd Publications

Discrepancies between previous experimental values of differential cross sections for electron-impact ionization of water vapor and recent model calculations have been largely resolved. A new measurement with improved suppression of spurious electrons has removed most of the discrepancy in the midrange of detected electron energies. A second discrepancy at secondary energies just below the primary energy has been explained by a more accurate accounting for electrons scattered at angles between zero and the minimum angle of the experimental apparatus. The improved data show more clearly the oxygen K-shell edge in the spectra at small angles and the Bethe ridge at ...


The Rainbow And The Achromatic Telescope: Two Case Studies, M. Eugene Rudd Jan 1988

The Rainbow And The Achromatic Telescope: Two Case Studies, M. Eugene Rudd

M. Eugene Rudd Publications

From the history of science we can learn not only some science and some history, but also something about how science is done and how it interacts with technology.
The First case study chosen illustrates the development of an understanding of a phenomenon of nature-one that has been observed with awe and wonder for as long as man has walked the Earth, but has only been well understood in the last 200 years. Some of the greatest thinkers of all time have worked on the problems of the rainbow.
The second study shows how an important invention became possible only ...