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ICPEAC XX: A Retro- and Pro-Spective Analysis

Description: There is something magical about ``round birthdays.`` They make one stop and think about where he is, how he got there, and where he is going. The same is apparently true of conferences, especially those like ICPEAC which represent the periodic coming together of a broad range of scientists in a reasonably well-defined discipline. This Vienna conference is the 20th in the ICPEAC series, and a retro- and pro-spective analysis seems appropriate. At the first ICPEAC in New York (1958), there were about 50 participants. In Vienna (1997), there were more than 800 participants. How do we account for this growth? ICPEAC is one of the most democratic conferences of its size. For example, input from a general committee of 50 representing the many geographic and sub- disciplinary areas gives continuous refreshment of ideas for the invited program. And, as in any democracy, there is a constant state of turmoil and self doubt. After all, atomic collisions is a ``mature`` field, and was a ``mature`` field at the time of the first ICPEAC in 1958, 50 what can one expect in new developments? This self doubt is best expressed in the comment of Ben Bederson (the ``Father of ICPEAC``) following the second in Boulder, Colorado, in 1961: ``This conference is the second in a series of informal meetings organized by a group of workers in the general field of electronic and atomic collisions. The first such meeting was held at New York University in 1958, and we will probably continue to meet at irregular intervals in the future....`` As part of my ``keynote`` talk at the New York ICPEAC XVI in 1989, I gave a brief history of the conference which we can build on to round things off for our twentieth.
Date: December 31, 1997
Creator: Datz, S.
Partner: UNT Libraries Government Documents Department

Correlation holography: imaging of atoms when sigma/sub inelastic//sup >>sigma/elastic

Description: Atomic-scale resolution of details is possible with this method, even if protons interact with the atoms overwhelmingly inelastically, i.e. when sigma/sub inelastic/ >>sigma/sub elastic/. Observation of small objects is compatible with quantum mechanics even if the disturbance of the object caused by the observation process is arbitrarily small.
Date: January 1, 1979
Creator: Csonka, P.L.
Partner: UNT Libraries Government Documents Department

Multiphoton processes: conference proceedings

Description: The chapters of this volume represent the invited papers delivered at the conference. They are arranged according to thermatic proximity beginning with atoms and continuing with molecules and surfaces. Section headings include multiphoton processes in atoms, field fluctuations and collisions in multiphoton process, and multiphoton processes in molecules and surfaces. Abstracts of individual items from the conference were prepared separately for the data base. (GHT)
Date: January 1, 1984
Creator: Lambropoulos, P. & Smith, S.J. (eds.)
Partner: UNT Libraries Government Documents Department

Analysis of the Interaction of 300-Mev Neutrons with Xenon

Description: Abstract: And investigation of the interactions between 300-Mev neutrons and xenon was made by means of a cloud chamber in a pulsed magnetic field of 21,700 gauss placed in the neutron beam of the 184-inch Berkeley cyclotron. Eighty-seven negative pion events and 257 other stars were analyzed. In addition an experimental check was made on the energy of the incoming neutrons. Classification, identification, and angular and energy distributions of prongs associated with all events are presented. Interpretations of results are given.
Date: October 17, 1956
Creator: Morris, Richard Herbert, 1928-
Partner: UNT Libraries Government Documents Department

Theoretical atomic collision physics. Final report, July 1, 1987-- June 30, 1995

Description: This is the final report of research activities supported by the most recent grant to the theoretical atomic collision physics program at Rice University. For this most recent 3-year grant, the focus has been the study of excitation and charge-transfer in atom-atom and ion-atom collisions. Emphasis has been placed on low-velocity collision processes involving initially excited atoms, including ``low Rydberg`` atoms. Two particular objectives of this research were to examine the dependence of state-changing collision cross sections and other observables on the orientation and alignment of the initial excited orbitals and to look for ``intracollisional interference`` effects, speculated to arise from spatially separated interactions during a collision involving a highly excited atom. A number of radiative and non-radiative charge transfer studies involving ground-state atoms and ions were continued from the previous grant period. Several unanticipated personnel changes prevented execution of some of the proposed research, including the studies of collisions involving negative ions and electron-attaching atoms and the development of new theoretical techniques for handling the ``strong coupling`` regime. These remain challenging and fundamentally important research topics. Research highlights briefly described in the report deal with: spherical and non-spherical low-Rydberg atom collisions; alignment effects in collisions of Na(3p) with He{sup +} ions; near-resonant electron capture at very low energies; ion-atom and ion-molecule collisions, including electron capture; and low- energy processes involving collisions of H{sup +} with He, Na, and K atoms. The report also lists publications since 1991 reporting on the grant work.
Date: December 1, 1995
Creator: Walters, G.K.
Partner: UNT Libraries Government Documents Department

Theory of Ionization by Electron Collisions

Description: The problem of calculating comprehensive sets of cross sections for ionization of atoms and molecules is reviewed. Emphasis is put on targets that are already ionized and lower-energy collisions for which the incident electron must be treated on a par with target electrons. The physical circumstances are discussed in which perturbation methods should be adequate, and special investigations are recommended to identify the relevant ranges of parameters more precisely and dependably. A new R-matrix approach is outlined which should permit rather simple, approximate, but dependable calculations when the perturbation methods fail.
Date: June 1976
Creator: Fano, Ugo & Inokuti, Mitio
Partner: UNT Libraries Government Documents Department

Proceedings of the Workshop on Electronic and Ionic Collision Cross Sections Needed in the Modeling of Radiation Interactions with Matter, Held at Argonne National Laboratory December 6-8, 1983

Description: The term modeling in the Workship title refers to the mathematical analysis of the consequences of many collision processes for characterizing the physical stage of radiation actions. It requires as input some knowledge of collision cross sections. Traditionally, work on cross sections and work on the modeling are conducted by separate groups of scientists. It was the purpose of the Workshop to bring these two groups together in a forum that would promote effective communication. Cross-section workers described the status of their work and told what data were available or trustworthy. Modeling workers told what kind of data were needed or were most important. Twenty-two items from the workshop were prepared separately for the data base.
Date: May 1984
Creator: Argonne National Laboratory
Partner: UNT Libraries Government Documents Department

Inelastic near-surface interactions. Proceedings of the Werner Brandt workshop

Description: This workshop is one of an annual series covering penetration phenomena of charged particles in matter. This specific workshop includes electron scattering, ion and atom scattering, stopping powers, and cluster ion impacts on solids. Abstracts were prepared for individual items in the proceedings for inclusion in the data base. (GHT)
Date: April 1, 1985
Partner: UNT Libraries Government Documents Department

1984 Bibliography of atomic and molecular processes

Description: This annotated bibliography includes papers on atomic and molecular processes published during 1984. Sources include scientific journals, conference proceedings, and books. Each entry is designated by one or more of the 114 categories of atomic and molecular processes used by the Controlled Fusion Atomic Data Center, Oak Ridge National Laboratory to classify data. Also indicated is whether the work was experimental or theoretical, what energy range was covered, what reactants were investigated, and the country of origin of the first author. Following the bibliographical listing, the entries are indexed according to the categories and according to reactants within each subcategory.
Date: April 1, 1985
Creator: Barnett, C.F.; Gilbody, H.B.; Gregory, D.C.; Griffin, P.M.; Havener, C.C.; Howard, A.M. et al.
Partner: UNT Libraries Government Documents Department

Survey of atomic processes in edge plasmas

Description: A review of the most important reactions of atomic and molecular hydrogen with the fusion edge plasma electrons and ions is presented. An appropriate characterization of the considered collision processes, useful in plasma edge studies (evaluated cross sections, reaction rates, energy gain/loss per collision, etc.) has been performed. While a complete survey of atomic physics of fusion edge plasmas will be given elsewhere shortly, we demonstrate here the relevance of the atomic collision processes for describing the physical state of edge plasmas and understanding the energy balance in cool divertor plasmas. It is found that the excited neutral species play an important role in the low-temperature, high-density plasmas.
Date: November 1, 1983
Creator: Janev, R.K.; Post, D.E.; Langer, W.D.; Evans, K.; Heifetz, D.B. & Weisheit, J.C.
Partner: UNT Libraries Government Documents Department

Atomic scale resolution with correlation holography

Description: For many atoms (including atoms of interest in biology) the elastic and inelastic photon scattering cross sections (denoted respectively by sigma/sub el/ and sigma/sub inel/) for photons in the wavelength region of interest, satisfy sigma/sub el/ << sigma/sub inel/. Therefore, the probability is high that when illuminated with photons, such an atom will decay before a holographic picture of it can be taken. On the other hand, if certain nonlinear phenomena: correlations between photons are taken into account, a hologram of such atoms can nevertheless be generated. Observation of small objects is compatible with the principles of quantum mechanics, even if the probability of disturbing the object as a result of observation is arbitrarily small.
Date: January 1, 1979
Creator: Csonka, P.L.
Partner: UNT Libraries Government Documents Department

Measurement of the Transverse Spitzer Resistivity during Collisional Magnetic Reconnection

Description: Measurement of the transverse resistivity was carried out in a reconnecting current sheet where the mean free path for the Coulomb collision is smaller than the thickness of the sheet. In a collisional neutral sheet without a guide field, the transverse resistivity is directly related to the reconnection rate. A remarkable agreement is found between the measured resistivity and the classical value derived by L. Spitzer. In his calculation the transverse resistivity for the electrons is higher than the parallel resistivity by a factor of 1.96. The measured values have verified this theory to within 30% errors.
Date: September 18, 2000
Creator: Trintchouk, F.; Yamada, M.; Ji, H.; Kulsrud, R.M. & Carter, T.A.
Partner: UNT Libraries Government Documents Department

Ion-Molecule Reactions

Description: Introduction: The present report is a critical review of the present knowledge and theory of ion-molecule reactions, especially as they may apply to high-level radiation processing.
Date: October 1959
Creator: Rosenstock, H. M.; Mueller, C. R.; Wallenstein, M. B.; Vestal, Marvin L.; Tory, Audrey; Rivers, Diana et al.
Partner: UNT Libraries Government Documents Department

Measurement of x-rays emitted from projectiles moving in solid targets

Description: The results of three separate experiments all dealing with the production of x-rays in projectiles moving in solids are discussed. The first experiment deals with the measurement of line widths of x-rays emitted from projectiles moving in solid targets. The effect of collisional broadening of x- rays is found to dominate the line widths giving greater than an order of magnitude increase in the measured line widths. The second experiment studies ''solid target effects'' in producing non-binomial distributions of characteristic K x-ray spectra in heavy ion-atom collisions. The third experiment studies aluminum K x-ray production in Ar$sup +$ $Yields$ Al collisions in very thin aluminum foils as a function of foil thickness. Parameterization of the observed non-linear dependence enables the lifetime of the argon 2p vacancy and total ionization cross sections for the argon L-shell in Ar $Yields$ Al collisions to be measured. (auth)
Date: January 1, 1975
Creator: Fortner, R.J.; Matthews, D.L.; Feldman, L.C.; Garcia, J.D. & Oona, H.
Partner: UNT Libraries Government Documents Department

Backscattering of light ions from metal surfaces

Description: When a metal target is bombarded with light ions some are implanted and some are reflected from the surface or backscattered from deeper layers. This results in an energy distribution of the backscattered particles which reaches from zero to almost the primary energy. The number of the backscattered particles and their energy, angular, and charge distributions depends largely on the energy and the ion target combination. For high energies (i.e., greater than50 keV for protons) particles are backscattered in a single collision governed by the Rutherford cross section. Protons and He-ions with energies of 100 keV to several MeV are widely used for thin film analysis. For lower energies multiple collisions and the screening of the Coulomb potential have to be taken into account, which makes the theoretical treatment more difficult. This energy region is, however, of special interest in the field of nuclear fusion research. Some recent results for energies below 20 keV are discussed in some detail. (auth)
Date: July 1, 1975
Creator: Verbeek, H.
Partner: UNT Libraries Government Documents Department

Ultra-cold molecule production.

Description: The production of Ultra-cold molecules is a goal of many laboratories through out the world. Here we are pursuing a unique technique that utilizes the kinematics of atomic and molecular collisions to achieve the goal of producing substantial numbers of sub Kelvin molecules confined in a trap. Here a trap is defined as an apparatus that spatially localizes, in a known location in the laboratory, a sample of molecules whose temperature is below one degree absolute Kelvin. Further, the storage time for the molecules must be sufficient to measure and possibly further cool the molecules. We utilize a technique unique to Sandia to form cold molecules from near mass degenerate collisions between atoms and molecules. This report describes the progress we have made using this novel technique and the further progress towards trapping molecules we have cooled.
Date: December 1, 2005
Creator: Ramirez-Serrano, Jamie; Chandler, David W.; Strecker, Kevin & Rahn, Larry A.
Partner: UNT Libraries Government Documents Department

Excitation states of projectiles moving through solids

Description: From 3rd international conference on atomic collisions in solids; Gatlinburg, Tennessee, USA (23 Sep 1973). X-ray spectral measurements of S, Cl, and Ar atoms moving in solid carbon targets are used to extract the equilibrium distribution of vacancies in the valence and L-shells of the projectiles. It is found that the state of excitation is much higher than the mean charge measured after the projectile has left the solid. A simple model is used to deduce the expected final charge state distribution, and these are compared to thin foil measurements. The results support the Betz-Grodzins model for ions moving in solids. (auth)
Date: September 1, 1973
Creator: Fortner, R.J. & Garcia, J.D.
Partner: UNT Libraries Government Documents Department

Acceleration and collision of ultra-high energy particles using crystal channels

Description: We assume that, independent of any near-term discoveries, the continuing goal of experimental high-energy physics (HEP) will be to achieve ultra-high center-of-mass energies early in the next century. To progress to these energies in such a brief span of time will require a radical change in accelerator and collider technology. We review some of our recent theoretical work on high-gradient acceleration of charged particles along crystal channels and the possibility of colliding them in these same strong-focusing atomic channels. An improved understanding of energy and emittance limitations in natural crystal accelerators leads to the suggestion that specially manufactured nano-accelerators may someday enable us to accelerate particles beyond 10{sup 8} eV with emittances limited only by the uncertainty principle of quantum mechanics.
Date: April 1, 1997
Creator: Chen, P. & Noble, R.J.
Partner: UNT Libraries Government Documents Department

Few electron transitions in atomic collisions. Final report, September 1, 1992--December 31, 1995

Description: During the past three years we have evaluated probabilities and cross sections for few and multiple electron transitions in atomic collisions. Our studies included interactions of atoms and molecules with incident protons, bare ions, electrons, positrons, anti-protons, ions carrying electrons and photons. We also: studied the inter-relation between collisions with charged particles and collisions involving various processes with photons. This work has complemented various studies of collisions of atoms with charged particles and with photons as well as more general efforts to understand the nature of multi-electron systems. Our aim has been to begin with relatively simple two electron systems and to focus on fast processes in which there is too little time for complicated processes to occur. We have used a variety of computational techniques, but we emphasize those appropriate for fast collisions in which we hope to obtain insight into the physical nature of the process itself. We generally considered systems in which experimental data was available.
Date: April 1, 1997
Creator: McGuire, J.
Partner: UNT Libraries Government Documents Department