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Track Structure And Radiation Transport Model For Space Radiobiology Studies, F. A. Cucinotta, J. W. Wilson, Robert Katz, W. Atwell, G. D. Badhwar, M. R. Shavers Jan 1996

Track Structure And Radiation Transport Model For Space Radiobiology Studies, F. A. Cucinotta, J. W. Wilson, Robert Katz, W. Atwell, G. D. Badhwar, M. R. Shavers

Robert Katz Publications

Radiobiology experiments performed in space are deemed necessary for validation of risk-assessment methods. The understanding of space radiobiology experiments must combine knowledge of the space radiation environment, radiation transport, and models of biological response. The heavy ion transport code HZETRN has recently been combined with improved models of the galactic cosmic rays (GCR) and extensive comparisons made to measurements on the space shuttle with a tissue equivalent, proportional counter. HZETRN was also coupled with track-structure models of biological damage from heavy ions. Track-structure calculations using improved models of the radial dose distribution around the path of heavy ions provide a …

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Scanning Force Microscopy For The Study Of Domain Structure In Ferroelectric Thin Films, Alexei Gruverman, O. Auciello, H. Tokumoto Jan 1996

Scanning Force Microscopy For The Study Of Domain Structure In Ferroelectric Thin Films, Alexei Gruverman, O. Auciello, H. Tokumoto

Alexei Gruverman Publications

A piezoresponse technique based on scanning force microscopy (SFM) has been used for studying domain structure in ferroelectric thin films. Studies were performed on Pb(Zrx,Ti1-x)O3(PZT) thin films produced by a sol–gel method. The piezoresponse images of the PZT films were taken before and after inducing polarization in the films by applying a direct current voltage between the bottom electrode and the SFM tip. Polarization induced patterns were written with 20 V pulses and subsequently imaged by the SFM piezoresponse technique. The effect of the film structure on the imaging resolution of domains is discussed.

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A Simple Model For Nonequilibrium Fluctuations In A Fluid, Alejandro Garcia, F. Baras, M. Malek Mansour Jan 1996

A Simple Model For Nonequilibrium Fluctuations In A Fluid, Alejandro Garcia, F. Baras, M. Malek Mansour

Faculty Publications

Presents a train model that shows the long-range spatial correlations of fluctuations in nonequilibrium fluid systems. Illustration of model through analysis of flat-car trains running on parallel tracks; Simulation of train model in computers; Theoretical analysis for fluctuations in the train model; Relationship between train model and the fluctuating hydrodynamic theory of fluids.

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Logic And The Second Law Of Thermodynamics, David Van Den Einde Jan 1996

Logic And The Second Law Of Thermodynamics, David Van Den Einde

Journal of the Minnesota Academy of Science

This paper presents a 2T thermodynamic cycle operating around the critical locus of ethylene. The cycle converts heat energy to work at a rate greater than the Carnot cycle. This energy conversion rate challenges the use of Carnot's thermodynamic efficiency as a foundation for the second Jaw of thermodynamics. The paper discusses the historical development of classical theory and the second law's foundation in logic.

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Type-Ii Interface Exciton In Znse/(Zn,Mn)Se Heterostructures, V V. Rossin, Thomas Böttger, F Henneberger Jan 1996

Type-Ii Interface Exciton In Znse/(Zn,Mn)Se Heterostructures, V V. Rossin, Thomas Böttger, F Henneberger

Physics and Astronomy

Two emission bands are observed in the photoluminescence spectrum of ZnSe/~Zn,Mn!Se heterostructures. These bands emerge in a magnetic field and are associated with interface excitons formed as a result of a magnetic-field-induced type-I–type-II transition of the band alignment. Time-resolved measurements yield lifetimes in the ns range signifying a relatively large spatial separation of electrons and holes and hence low optical oscillator strength. These features are confirmed by a theoretical analysis of the interface exciton state revealing a reduced importance of the electron-hole Coulomb interaction in comparison with type-II excitons in quantum wells.

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Model-Observation Comparison Study Of Multiple Polar Cap Arcs, Lie Zhu, Cesar E. Valladares, Jan Josef Sojka, Robert W. Schunk, D. J. Crain Jan 1996

Model-Observation Comparison Study Of Multiple Polar Cap Arcs, Lie Zhu, Cesar E. Valladares, Jan Josef Sojka, Robert W. Schunk, D. J. Crain

All Physics Faculty Publications

A quantitative model-observation comparison of multiple polar cap arcs has been conducted by using a time-dependent theoretical model of polar cap arcs. In particular, the electrodynamical features of multiple polar cap arcs with various spacings are simulated and the results are compared with the images obtained from the All-Sky Intensified Photometer at Qaanaaq. The results show that the observed and simulated arcs are quite similar, both spatially and temporally. The results support the theory proposed by Zhu et al. [1993a, 1994b] that the structure of polar cap arcs is mainly determined by the magnetosphere-ionosphere (M-I) coupling processes and that …

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Translation Of 'Profiles In Faith', Monish Ranjan Chatterjee Jan 1996

Translation Of 'Profiles In Faith', Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

Sarat Chandra Chatterjee (1876-1938) may be considered one of the three most significant figures of the literary component of the Bengal Renaissance, the other two being Bankim Chandra Chatterjee (1838-1894) and Rabindranath Tagore (1861-1941). As much as Bankim Chandra is identified with the new age in the Bengali novel, and the development of serious vernacular journalism, and Rabindranath with modern/classical movements in Bengali poetry and music, along with novel ideas in methods of education and teaching, Sarat Chandra, as a novelist and storyteller, perfected the art of narration and critical analyses of a variety of contemporaneous social and political issues, …

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The Calculation Of Radial Dose From Heavy Ions: Predictions Of Biological Action Cross Sections, Robert Katz, Francis A. Cucinotta, C. X. Zhang Jan 1996

The Calculation Of Radial Dose From Heavy Ions: Predictions Of Biological Action Cross Sections, Robert Katz, Francis A. Cucinotta, C. X. Zhang

Robert Katz Publications

The track structure model of heavy ion cross sections was developed by Katz and co-workers in the 1960s. In this model the action cross section is evaluated by mapping the dose-response of a detector to γ rays (modeled from biological target theory) onto the radial dose distribution from 6 rays about the path of the ion. This is taken to yield the radial distribution of probability for a "hit" (an interaction leading to an observable end-point). Radial integration of the probability yields the cross section. When different response from ions of different Z having the same stopping power is observed …

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Donald J. Montgomery, Sitaram Jaswal, John Hardy, Paul M. Parker Jan 1996

Donald J. Montgomery, Sitaram Jaswal, John Hardy, Paul M. Parker

John R. Hardy Papers

Donald J. Montgomery, long a research professor at Michigan State University, died suddenly from a stroke on 19 January at the age of 78.

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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 electron yields are …

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Intraocular Lens Case Designs, Donald S. Remer, Stephen S. Davis, Michael Bak '95, Ken Kalafus, Ilan Sabar, Khannan Suntharam, William Washington, Yu-Tung Wong Jan 1996

Intraocular Lens Case Designs, Donald S. Remer, Stephen S. Davis, Michael Bak '95, Ken Kalafus, Ilan Sabar, Khannan Suntharam, William Washington, Yu-Tung Wong

All HMC Faculty Publications and Research

IOLAB Corporation makes two types of intraocular lenses for the replacement of cataracts: one from polymethyl methacrylate (PMMA) and a newer one from silicone. IOLAB ships the lens to the doctor in a two-piece case made from polycarbonate. At a price of $0.53 per case, IOLAB spends about $270,000 per year on lens cases (based on 1994 purchases of 500,000 cases). IOLAB asked us to reduce the cost of the existing lens case and to design a new case to protect and fold the silicone lens. We designed three items.

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Internal Time Formalism For Spacetimes With Two Killing Vectors, Joseph D. Romano, Charles G. Torre Jan 1996

Internal Time Formalism For Spacetimes With Two Killing Vectors, Joseph D. Romano, Charles G. Torre

All Physics Faculty Publications

The Hamiltonian structure of spacetimes with two commuting Killing vector fields is analyzed for the purpose of addressing the various problems of time that arise in canonical gravity. Two specific models are considered: (i) cylindrically symmetric spacetimes, and (ii) toroidally symmetric spacetimes, which respectively involve open and closed universe boundary conditions. For each model canonical variables which can be used to identify points of space and instants of time, {\it i.e.}, internally defined spacetime coordinates, are identified. To do this it is necessary to extend the usual ADM phase space by a finite number of degrees of freedom. Canonical transformations …

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Resonance Lidar To Study Temperatures, Winds, And Metal Densities In The Upper Mesosphere And Lower Thermosphere, Vincent B. Wickwar, T D. Wilkerson, D Rees, S C. Collins Jan 1996

Resonance Lidar To Study Temperatures, Winds, And Metal Densities In The Upper Mesosphere And Lower Thermosphere, Vincent B. Wickwar, T D. Wilkerson, D Rees, S C. Collins

All Physics Faculty Publications

None available.

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Residential Radon-222 Exposure And Lung Cancer: Exposure Assessment Methodology, R. William Field, Daniel J. Steck, Charles F. Lynch, Christine P. Brus, John S. Neuberger, Burton C. Kross Jan 1996

Residential Radon-222 Exposure And Lung Cancer: Exposure Assessment Methodology, R. William Field, Daniel J. Steck, Charles F. Lynch, Christine P. Brus, John S. Neuberger, Burton C. Kross

Physics Faculty Publications

Although occupational epidemiological studies and animal experimentation provide strong evidence that radon-222 (222Rn) progeny exposure causes lung cancer, residential epidemiological studies have not confirmed this association. Past residential epidemiological studies have yielded contradictory findings. Exposure misclassification has seriously compromised the ability of these studies to detect whether an association exists between 222Rn exposure and lung cancer. Misclassification of 222Rn exposure has arisen primarily from: 1) detector measurement error; 2) failure to consider temporal and spatial 222Rn variations within a home; 3) missing data from previously occupied homes that currently are inaccessible; 4) failure to link …

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Experimental And Theoretical Investigation Of Recombination Pumped X-Ray Lasers Driven By High-Intensity, Short Pulse Lasers, Thomas D. Donnelly, L. Da Silva, R. W. Lee, S. Mrowka, M. Hofer, R. W. Falcone Jan 1996

Experimental And Theoretical Investigation Of Recombination Pumped X-Ray Lasers Driven By High-Intensity, Short Pulse Lasers, Thomas D. Donnelly, L. Da Silva, R. W. Lee, S. Mrowka, M. Hofer, R. W. Falcone

All HMC Faculty Publications and Research

We have experimentally investigated a recombination-pumped soft-x-ray laser on a Lyman-α transition (135 Å) of hydrogenlike lithium. Furthermore, we have modeled the dynamics of this system, including the effects of the multipeaked electron distribution function that is obtained from the sequential, optical-field ionization of an atom. We compare the predictions of our model and our experimental results.

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Scale-Invariant Phase Space And The Conformal Group, James Thomas Wheeler Jan 1996

Scale-Invariant Phase Space And The Conformal Group, James Thomas Wheeler

All Physics Faculty Publications

The gauge bundle of the 4-dim conformal group over an 8-dim base space, called biconformal space, is shown have a consistent interpretation as a scale-invariant phase space. Specifically, we show that a classical Hamiltonian system generates a differential geometry which is necessarily biconformal, and that the classical Hamiltonian dynamics of a point particle is equivalent to the specification of a 7-dim hypersurface in flat biconformal space together with the consequent necessary existence of a set of preferred curves. The result is centrally important for establishing the physical interpretation of conformal gauging.

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Dendrimeric Liquid Crystals: Isotropic-Nematic Pretransitional Behavior, Jian-Feng Li, Karl A. Crandall, Peihwei Chu, Virgil Percec, Rolfe G. Petschek, Charles Rosenblatt Jan 1996

Dendrimeric Liquid Crystals: Isotropic-Nematic Pretransitional Behavior, Jian-Feng Li, Karl A. Crandall, Peihwei Chu, Virgil Percec, Rolfe G. Petschek, Charles Rosenblatt

Faculty Scholarship

Kerr measurements, ellipsometry, and quasielastic light scattering have been used to probe nematic fluctuations and nematic wetting at an isotropic liquid crystal-substrate interface in four generations of liquid crystalline monodendrons and dendrimers. We find that the pretransitional behavior is qualitatively similar to that of low molecular weight liquid crystals, exhibiting a Landau-like divergence of the relaxation time and a logarithmic divergence of the optical retardation on approaching the nematic-isotropic phase transition from above. Quantitatively, we find that the transition temperatures of the monodendrons are typically about 0.5 K above the supercooling limit of the isotropic phase and that the orientational …

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A Pathsearch Damped Newton Method For Computing General Equilibria, Steven P. Dirkse, Michael C. Ferris Jan 1996

A Pathsearch Damped Newton Method For Computing General Equilibria, Steven P. Dirkse, Michael C. Ferris

University Faculty Publications and Creative Works

Computable general equilibrium models and other types of variational inequalities play a key role in computational economics. This paper describes the design and implementation of a pathsearch damped Newton method for solving such problems. Our algorithm improves on the typical Newton method (which generates and solves a sequence of LCPs) in both speed and robustness. The underlying complementarity problem is reformulated as a normal map so that standard algorithmic enhancements of Newton's method for solving nonlinear equations can be easily applied. The solver is implemented as a GAMS subsystem, using an interface library developed for this purpose. Computational results obtained …

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Relationship Of Theoretical Patch Climatology To Polar Cap Patch Observations, M. D. Bowline, Jan Josef Sojka, Robert W. Schunk Jan 1996

Relationship Of Theoretical Patch Climatology To Polar Cap Patch Observations, M. D. Bowline, Jan Josef Sojka, Robert W. Schunk

All Physics Faculty Publications

During a southward orientation of the interplanetary magnetic field (IMF), patches are often observed moving antisunward across the polar cap. In saying “patches” we refer to structures in which the F region electron densities are enhanced relative to lower background levels; we do not in this paper consider patches which are observed optically (see J. J. Sojka et al., Ambiguity in identificiation of polar cap F region patches, submitted to the Journal of Atmospheric and Terrestrial Physics, 1995). The patches can be modeled by a process which involves the “chopping up” of the tongue of ionization (TOI) [Sojka …

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Multiple Polar Cap Arcs: Akebono (Exos D) Observations, T. Obara, T. Mukai, H. Hayakawa, K. Tsurda, A. Matsuoka, A. Nishida, H. Fukunishi, L. Zhu, Jan Josef Sojka, D. J. Crain Jan 1996

Multiple Polar Cap Arcs: Akebono (Exos D) Observations, T. Obara, T. Mukai, H. Hayakawa, K. Tsurda, A. Matsuoka, A. Nishida, H. Fukunishi, L. Zhu, Jan Josef Sojka, D. J. Crain

All Physics Faculty Publications

Akebono (Exos D) observations demonstrate that polar cap arcs sometimes have a fine structure, that is, multiple (double or triple) arcs with spacing of a few tens of kilometers. The multiple polar cap arcs are dominantly observed in the nightside polar cap region, suggesting that low background conductance favors the appearance of the structured arcs. A relationship between the spacing and the average energy of the precipitating electrons is investigated. Results show that a higher energy leads to a wider spacing. Akebono observations also show the existence of a downward current region embedded between upward current regions (arcs). Comparison of …

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Raman Spectroscopy Of Carbon Materials, Jr Dennison, Mark Holtz, Greg Swain Jan 1996

Raman Spectroscopy Of Carbon Materials, Jr Dennison, Mark Holtz, Greg Swain

Journal Articles

Use of carbon materials is no longer limited to diamond jewelry or graphite pencils and lubricants. The last decade has witnessed an explosion of technological applications driven by the development of fabrication methods and the discovery of several new classes of pure carbon. Structural diversity exhibited by the carbon atoms, from local chemical order to long-range crystalline order, is key to understanding their physical and chemical properties and in future materials development. This article summarizes the use of Raman spectroscopy as a principal tool to investigate the vibrational dynamics of carbon materials and to provide indirect structural characterization of their …

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Application Of (E,2e) Spectroscopy To The Electronic Structure Of Valence Electrons In Crystalline And Amorphous Solids, Jr Dennison, A. L. Ritter Jan 1996

Application Of (E,2e) Spectroscopy To The Electronic Structure Of Valence Electrons In Crystalline And Amorphous Solids, Jr Dennison, A. L. Ritter

Journal Articles

This review presents theoretical and experimental aspects of (e,2e) spectroscopy specific to the study of crystalline and amorphous solids. The cross section for (e,2e) scattering is proportional to the spectral momentum density of the ejected electron under certain approximations. The theoretical framework for interpreting (e,2e) measurements is summarized here and general properties of the spectral momentum density of solids are discussed. Different designs of the (e,2e) spectrometer are described and sample preparation techniques are briefly reviewed. A summary of recent (e,2e) experiments on the electronic structure of valence electrons in graphite, ion sputtered and evaporated amorphous carbon, and aluminum-aluminum oxide …

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Theoretical Hei Line Intensities In Gaseous Nebulae: Ngc 1976, 6572 And Ic 4997, J. B. Kingdon, Gary J. Ferland Jan 1996

Theoretical Hei Line Intensities In Gaseous Nebulae: Ngc 1976, 6572 And Ic 4997, J. B. Kingdon, Gary J. Ferland

Physics and Astronomy Faculty Publications

Smits has recently calculated theoretical He I intensities for a large number of lines for conditions appropriate to gaseous nebulae. These are likely to remain the definitive calculations for some time to come. A comparison of these line ratios with observed values in three nebulae reveals some discrepancies. We show that these discrepancies are reduced when collisional effects from the metastable 23S level are included, and that it is not necessary to invoke an unknown depopulation mechanism for the He I23S level.

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Magnetophotoluminescence Study Of Excited States Associated With Donor Bound Excitons In High-Purity Gaas, D. C. Reynolds, David C. Look, B. Jogai, G. L. Mccoy, K. K. Bajaj Jan 1996

Magnetophotoluminescence Study Of Excited States Associated With Donor Bound Excitons In High-Purity Gaas, D. C. Reynolds, David C. Look, B. Jogai, G. L. Mccoy, K. K. Bajaj

Physics Faculty Publications

Detailed magnetic-field splitting of the two rotator states designated as (Γ6+Γ8, J=5/2) and (Γ7, J=1/2) associated with donor bound excitons in high-purity epitaxial GaAs is observed in magnetophotoluminescence spectra. These two states are associated with the light-hole mass and are split by the spin-orbit interaction. The ordering in energy of these two states agrees with that predicted by theory. Also observed are the rotator states in which, after the radiative collapse of the exciton, the donor is left in the excited states. A good agreement between the energies of the excited states of the …

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Wet Chemical Digital Etching Of Gaas At Room Temperature, Gregory C. Desalvo, Christopher A. Bozada, John L. Ebel, David C. Look, John P. Barrette, Charles L. A. Cerny, Ross W. Dettmer, James K. Gillespie, Charles K. Havasy, Thomas J. Jenkins, Kenichi Nakano, Carl I. Pettiford, Tony K. Quach, James S. Sewell, G. David Via Jan 1996

Wet Chemical Digital Etching Of Gaas At Room Temperature, Gregory C. Desalvo, Christopher A. Bozada, John L. Ebel, David C. Look, John P. Barrette, Charles L. A. Cerny, Ross W. Dettmer, James K. Gillespie, Charles K. Havasy, Thomas J. Jenkins, Kenichi Nakano, Carl I. Pettiford, Tony K. Quach, James S. Sewell, G. David Via

Physics Faculty Publications

A new room temperature wet chemical digital etching technique for GaAs is presented which uses hydrogen peroxide and an acid in a two‐step etching process to remove GaAs in approximately 15 Å increments. In the first step, GaAs is oxidized by 30% hydrogen peroxide to form an oxide layer that is diffusion limited to a thickness of 14 to 17 Å for time periods from 15 to 120 s. The second step removes this oxide layer with an acid that does not attack unoxidized GaAs. These steps are repeated in succession until the desired etch depth is obtained. Experimental results …

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Effects Of In Profile On Material And Device Properties Of Algaas/Ingaas/Gaas High Electron Mobility Transistors, David C. Look, B. Jogai, R. Kaspi, J. L. Ebel, K. R. Evans, R. L. Jones, K. Nakano, R. E. Sherriff, C. E. Stutz, G. C. Desalvo, C. Ito Jan 1996

Effects Of In Profile On Material And Device Properties Of Algaas/Ingaas/Gaas High Electron Mobility Transistors, David C. Look, B. Jogai, R. Kaspi, J. L. Ebel, K. R. Evans, R. L. Jones, K. Nakano, R. E. Sherriff, C. E. Stutz, G. C. Desalvo, C. Ito

Physics Faculty Publications

The molecular‐beam‐epitaxial growth of InxGa1−xAs on GaAs or AlyGa1−yAs leads to a variation of In content with depth, due to In segregation. However, by predepositing In at the beginning of InxGa1−xAs growth, and also thermally removing the excess In at the end, we can produce a layer with the ideal ‘‘square’’ In profile. We find that the performance of AlyGa1−yAs/InxGa1−xAs/GaAs high electron mobility transistors is most enhanced by the predeposition step alone.

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Measuring Strangeness Production From Relativisitic Collisions Between Pairs Of Nuclei Using A Vertex Time Projection Chamber, Christine A. Byrd, Wilfred J. Braithwaite Jan 1996

Measuring Strangeness Production From Relativisitic Collisions Between Pairs Of Nuclei Using A Vertex Time Projection Chamber, Christine A. Byrd, Wilfred J. Braithwaite

Journal of the Arkansas Academy of Science

At collider energies of 200A-GeV, tracking of charged particle pairs originating from neutrals is dominated by singlystrange KJ.' decays. Counting the number ofsecondary vertex pairs is a method of measuring the strangeness production. The VTX is a four-layer micro-strip gas time projection chamber being designed for use with the STAR instrument in an experiment using the Relativistic Heavy Ion Collider under construction at Brookhaven National Laboratory. Simulated pixel data generated from CERN's Monte Carlo detector-modeling program Geant were put into tables using the TAS sorting structures available from the STAR Collaboration. The response of VTX was mapped for charged pion …

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Imaging Of Saddle Point Electron Emission In Slow, R. Dörner, H. Khemliche, M. H. Prior, C. L. Cocke, J. A. Gary, Ronald E. Olson, V. Mergel, J. Ullrich, H. Schmidt-Böcking Jan 1996

Imaging Of Saddle Point Electron Emission In Slow, R. Dörner, H. Khemliche, M. H. Prior, C. L. Cocke, J. A. Gary, Ronald E. Olson, V. Mergel, J. Ullrich, H. Schmidt-Böcking

Physics Faculty Research & Creative Works

The two-dimensional velocity distribution of electrons emitted in 5-15 keV p - He collisions has been measured for completely determined motion of the nuclei, that is, as a function of the impact parameter and in a well defined scattering plane. The electrons are emitted preferentially in the scattering plane and in the forward direction. The velocity distributions show sharp structures that vary strongly with impact parameter and projectile velocity. The results are compared to classical trajectory calculations. © 1996 The American Physical Society.

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Effective-Medium Theory For The Electric-Field Dependence Of The Hopping Conductivity Of Disordered Solids, Paul Ernest Parris, B. D. Bookout Jan 1996

Effective-Medium Theory For The Electric-Field Dependence Of The Hopping Conductivity Of Disordered Solids, Paul Ernest Parris, B. D. Bookout

Physics Faculty Research & Creative Works

We derive a general effective-medium theory for describing biased diffusion on a bond-disordered lattice in the presence of an external driving field. In our theory, the effective medium associated with a disordered d-dimensional lattice is characterized, for each value of the applied field, by 2d independent parameters describing, respectively, the net drift velocity vv and the diffusion constant Dvv describing the spread of a carrier packet about its mean value, for each of the d crystal axes. The theory correctly predicts the velocity transition occurring in an exactly soluble model studied by Derrida and, in contrast to other …

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Collective Behavior Of Electrons Emitted In Multiply Ionizing Collisions Of 5.9 Mev/U U⁶⁵⁺ With Ne, M. Unverzagt, R. Moshammer, W. Schmitt, Ronald E. Olson, P. Jardin, V. Mergel, J. Ullrich, H. Schmidt-Böcking Jan 1996

Collective Behavior Of Electrons Emitted In Multiply Ionizing Collisions Of 5.9 Mev/U U⁶⁵⁺ With Ne, M. Unverzagt, R. Moshammer, W. Schmitt, Ronald E. Olson, P. Jardin, V. Mergel, J. Ullrich, H. Schmidt-Böcking

Physics Faculty Research & Creative Works

The collective behavior of up to six target electrons emitted in a single collision of 5.9 MeV/u U65+ with Ne was investigated using high-resolution recoil-ion momentum spectroscopy. With an increasing number of ejected electrons the recoil ions are increasingly scattered into the backward direction, providing evidence that the electrons are emitted into the forward hemisphere. Their mean longitudinal sum energy varies from about 5 eV for single ionization up to 1.1 keV for Ne6+. Experimental recoil-ion momentum distributions are in excellent agreement with results of classical many-particle calculations. © 1996 The American Physical Society.

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