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Atomic collisions with 33-TeV lead ions

Description: Recent availability of relativistic and ultrarelativistic beams of heavy ions has permitted the first controlled studies of atomic collisions at energies sufficient to measure effects of several new basic phenomena. These include measurements substantiating recently predicted finite nuclear size effects resulting in a reduction in the total electronic energy loss of heavy ions in matter, and measurements of Coulomb collisions in which electrons are excited from the Dirac negative energy continu… more
Date: October 1, 1996
Creator: Vane, C. R.; Datz, S. & Krause, H. F.
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Partner: UNT Libraries Government Documents Department
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Non-statistically populated autoionizing levels of Li-like carbon: Hidden-crossings

Description: The intensities of the Auger-electron lines from autoionizing (AI) states of Li-like (1s2s2l) configurations excited in ion-atom collisions vary as functions of the collision parameters such as, for example, the collision velocity. A statistical population of the three-electron levels is at best incomplete and underscores the intricate dynamical development of the electronic states. The authors compare several experimental studies to calculations using ``hidden-crossing`` techniques to explore … more
Date: December 31, 1995
Creator: Deveney, E. F.; Krause, H. F. & Jones, N. L.
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Partner: UNT Libraries Government Documents Department
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Electron-positron pair production in ultrarelativistic atomic collisions: 6.4 TeV S{sup 16+} with Au, Pd and Al

Description: Angular and momentum distributions have been measured for electron-positron pairs created in peripheral collisions of 6.4 TeV bare sulfur ions with thin targets of Al, Pd, and Au. Singly- and doubly-differential cross sections are presented for 1--17 MeV/c electrons and positrons detected independently and in coincidence as pairs. Various physical parameters are deduced from the coincident electron and positron data, including probability distributions for the pair transverse momentum, the pair… more
Date: October 1, 1994
Creator: Datz, S.; Vane, C. R.; Dittner, P. F.; Krause, H. F.; Schuch, R.; Gao, H. et al.
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Partner: UNT Libraries Government Documents Department
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Electron ion interactions in crystal channels: Collisions in ultra-dense electron media

Description: Dielectronic excitation of H-like S, Ca and Ti is shown to occur in the dense electron gas of a crystal channel. Cross sections for collisional ionization of the short lived excited states can then be determined. Ionic excitation can also be achieved by resonant coherent excitation in which case specific m states can be excited for further study. 12 refs., 8 figs.
Date: January 1, 1990
Creator: Datz, S.; Dittner, P. F.; Gomez del Campo, J.; Krause, H. F.; Rosseel, T. M. & Vane, C. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Measurement of Electromagnetic Cross Sections in Heavy Ion Interactions and Its Consequences for Luminosity Lifetimes in Ion Colliders

Description: The limitation of the luminosity lifetime in high energy heavy ion colliders like RHIC or LHC operating in ion mode is set by the very large cross section of beam - beam interactions. One of the dominant processes at relativistic energies is electron capture from pair production in the strong electromagnetic field provided by the high Z of the ions. The capture cross sections for Pb<sup>82+</sup> interacting with a number targets have been measured using one of the high energy resolution 158 Ge… more
Date: March 29, 1999
Creator: Datz, S.; Grafstroem, P.; Knudsen, H.; Krause, H. F.; Mikkelsen, U.; Scheidenberger, C. et al.
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Partner: UNT Libraries Government Documents Department
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Electrons Emitted from 33-TeV Pb Ions During Penetration of Solids

Description: At ultrarelativistic energies, ionization cross sections exceed electron capture cross sections by several orders of magnitude (1,2). Effectively, all electrons transferred to a highly relativistic heavy ion moving in a solid or gaseous target medium are stripped in a relatively short distance. Above ~20 GeV/nucleon, the principal mechanism for electron capture is from pair production (ECPP) (2). The total cross sections for ECPP are te&nically important for making reliable predictions of opera… more
Date: July 22, 1999
Creator: Datz, S.; Grafstroem, P.; Knudsen, H.; Krause, H. F.; Mikkelsen, U.; Moeller, S. et al.
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Partner: UNT Libraries Government Documents Department
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Resonant coherent excitation of N{sup 6+} and Mg{sup 11+} in planar channeling: Anisotropies in ionization probabilities and x-ray emission

Description: The thrust of the conference in which this paper is presented is toward inelastic interactions of ions with surfaces. The work described in this paper deals with inelastic interactions of ions in planar channeling inside the crystal. The authors are, however, not too far off the mark because the planar channeling potential is made up from the sum of two (sheet) surface potentials. For the nitrogen experiment, a beam of N{sup 6+} ions at an energy of 3.25 MeV/amu was supplied by the ORNL EN Tand… more
Date: December 31, 1994
Creator: Datz, S.; Dittner, P. F.; Krause, H. F.; Vane, C. R.; Crawford, O. H.; Forster, J. S. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Resonant coherent excitation of Mg sup 11+ : Electronic collisions of state specified short-lived excited states in a crystal channel

Description: Hydrogenic ions passing through axial and planar channels can be excited from n = 1 to n = 2 when the frequency of perturbation by the atoms in the crystal spaced a distance d apart comes into resonance with the spacing between eigenstates i and j {Delta}E{sub ij} = hK(v{sub i}/d) where K is a harmonic 1,2,3{hor ellipsis} of the (v{sub i}/d) frequency. The degeneracy in the n = 2 levels is removed; first by the assymetry in the crystal field and second by Stark mixing of 2s with 2p{sub x} which… more
Date: January 1, 1990
Creator: Datz, S.; Dittner, P. F.; Gomez del Campo, J.; Krause, H. F.; Rosseel, T. M.; Vane, C. R. (Oak Ridge National Lab., TN (USA)) et al.
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Partner: UNT Libraries Government Documents Department
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Excitation curve for auger decay of the (1S2S2P sup 2 ) sup 3 D state of C sup 4+ formed through RTE (Resonant Transfer and Excitation)

Description: The ORNL EN tandem supplied beams of 3.5--9 MeV C{sup 3+} ions which were incident on a differentially pumped He target. Auger electrons emitted by fast C{sup 4+} ions emerged at 10 deg(lab)w.r.t. the incident ion beam. They were detected using a two stage spectrometer with kinematic refocusing. An excitation curve was obtained for the (1s2s2p){sup 3}D state Auger decay to the ground state of C{sup 3+}. The excitation curve peaks at {approximately}6 MeV, which strongly supports the notion that … more
Date: January 1, 1990
Creator: Shafroth, S. M.; McDonald, F.; Benhenni, M. (North Carolina Univ., Chapel Hill, NC (USA)); Kessel, Q.; Deveney, E. (Connecticut Univ., Storrs, CT (USA)); Swenson, J. K. et al.
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Partner: UNT Libraries Government Documents Department
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