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1989

Physics

University of Nebraska - Lincoln

Articles 31 - 37 of 37

Full-Text Articles in Physical Sciences and Mathematics

Low-Energy Features Of The E--H(N=2) System Exhibited In Fast H- Detachment Collisions, Chih-Ray Liu, Anthony F. Starace Jan 1989

Low-Energy Features Of The E--H(N=2) System Exhibited In Fast H- Detachment Collisions, Chih-Ray Liu, Anthony F. Starace

Anthony F. Starace Publications

Quantitative predictions for the doubly differential detachment collisions, 0.5-MeV H-+He→H(n=2)+He*+e-, are provided by use of hyperspherical wave functions for the H-e- system. Individual H-e- hyperspherical channels are identified as producing distinct "cusp," "shape resonance," and/or "shoulder" features in the laboratory-frame cross sections. Moreover, the first quantitative predictions of the expected Gailitis-Damburg dipole-field-induced oscillations in the cross sections above the H(n=2) threshold are presented and distinguished from 1P∘ shape resonance effects.

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Track “Core” Effects In Heavy Ion Radiolysis, Robert Katz, Guo-Rong Huang Jan 1989

Track “Core” Effects In Heavy Ion Radiolysis, Robert Katz, Guo-Rong Huang

Robert Katz Publications

By assuming that HO2● radical production in water and H2 production in benzene are 2 hit processes, and applying the concepts of track physics, we are able to obtain a parametric fit to the yields of these reactions by heavy ion radiolysis from knowledge of the radial dose distribution about a heavy ion’s path. We make no use of the concept of a track core, for no clearly definable track core appears in our calculations of the radial dose distribution. Instead we calculate an action cross section σ from the assumed 2 hit response to γ-rays. The …

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Perspectives On The Development Of Track Physics, Robert Katz Jan 1989

Perspectives On The Development Of Track Physics, Robert Katz

Robert Katz Publications

Let me thank all of you for being here, Tony Starace, for having conceived this meeting, and Bob Wood and Matesh Varma, for over 20 years of support without which there would have been no track physics. There are many others to thank: the students, postdoctorates, and senior visitors who actually did all the work, and the many investigators around the world who made measurements that proved to be essential to developing and testing the notions of particle tracks.

This enterprise began when I undertook to rewrite an introductory physics text by Henry Semat to adapt it to a calculus-based …

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Theoretical Study Of Lattice Instabilities In Yba2Cu3O7, D. P. Billesbach, John R. Hardy, P. J. Edwardson Jan 1989

Theoretical Study Of Lattice Instabilities In Yba2Cu3O7, D. P. Billesbach, John R. Hardy, P. J. Edwardson

John R. Hardy Papers

We have performed a molecular dynamics simulation of the YBa2Cu3O7 structure under the constraints of the rigid-ion model. These simulations used a variety of charge states for the Cu ions and the O ions, and except for one case, the interionic potentials were obtained in an ab initio fashion. The results of these simulations showed that a lattice instability involving the Cu-O chains existed. This instability was further investigated and it was shown that simple electronic screening is probably insufficient to stabilize the lattice. An instability of this nature provides a simple explanation of some …

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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 …

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The Coupling Of Stimulated Raman And Brillouin Scattering In A Plasma, Donald P. Umstadter, W.B. Mori, C. Joshi Jan 1989

The Coupling Of Stimulated Raman And Brillouin Scattering In A Plasma, Donald P. Umstadter, W.B. Mori, C. Joshi

Donald Umstadter Publications

The observation of an anti-Stokes satellite in the spectrum of light backscattered from a CO2 laser plasma is reported. Its origin is found to be Thomson scattering of the incident light from a counterpropagating mode-coupled plasma wave. The parent electron and ion waves in the mode-coupling process were driven by stimulated Raman and Brillouin backscattering. The parent and daughter plasma waves were detected by ruby laser Thomson scattering. A computer simulation modeling the experiment shows further cascading of the Stokes backscattered light to lower frequencies, apparently a result of its rescattering from another, higher phase velocity, counterpropagating coupled mode. …

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Robert Katz: A Biographical Sketch, M. Eugene Rudd, John F. Fowler Jan 1989

Robert Katz: A Biographical Sketch, M. Eugene Rudd, John F. Fowler

Robert Katz Publications

Robert Katz was born in 1917 in New York City of Russian- Jewish immigrant parents. He grew up in the Bronx, attended Brooklyn College where he received his B.A. degree in 1937. A year later he was awarded the M.A. degree in physics at Columbia University. During World War II he worked for the Air Force at Wright Field in Ohio. After the war he returned to academia as a graduate student at the University of Illinois, where he earned the Ph.D. degree in physics in 1949. From that year he was a member of the Department of Physics at …

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