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Atomic collisions with 33-TeV lead ions

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Non-statistically populated autoionizing levels of Li-like carbon: Hidden-crossings

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Measurement of inelasticities for charge correlated multiple ionization of Ne by fast C/sup 6 +/ ions

A description of measurements of inelasticities for multiple ionization in fast-single collisions is given for the example of 10 MeV C/sup 6 +/ ions with Ne atoms. The degree of multiple ionization was determined by time-of-flight of the recoil ions, extracted by an electric field in coincidence with the projectiles. Their energy loss for a given degree of multiple ionization was measured with a position-sensitive silicon detector in the focal plane of an Elbek magnetic spectrograph with an ene… more

Date: January 1, 1987

Creator: Schuch, R.; Datz, S.; Dittner, P. F.; Krause, H. F. & Miller, P. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Strong forward-backward asymmetries in electron emission from overlapping resonance states in fast C/sup 3 +/ on He collisions

Autoionizing electrons from the configuration 1s/sup 2/2pnl produced by transfer and excitation were measured for 2.5 to 5.0 MeV C/sup 3 +/ + He-gas collision employing the method of zero-degree Auger spectroscopy. The elctron analyzer was operated with an energy resolution of 300 MeV (FWHM), which corresponds to the projectile rest frame energy resolution (approx.40 MeV). (WRF)

Date: January 1, 1986

Creator: Yamazaki, Y.; Miller, P. D.; Krause, H. F.; Pepmiller, P. L.; Datz, S. & Sellin, I. A.

Item Type: Article

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

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron ion interactions in crystal channels: Collisions in ultra-dense electron media

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: Article

Partner: UNT Libraries Government Documents Department

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Heavy-ion-induced x-ray satellite emission as a chemical probe

Advances in energy technology often require correspondidng advances in materials fabrication and characterization. Among the new techniques being developed for the improved characterization of materials is an x-ray fluorescence method which uses heavy ions for excitation. High resolution measurements of heavy-ion excited x-ray spectra have revealed a series of prominent satellite lines in addition to the normal emission lines. It has been shown that these satellites display intensity variations… more

Date: January 1, 1983

Creator: Rosseel, T. M.; Dale, J. M.; Hulett, L. D.; Krause, H. F.; Raman, S.; Vane, C. R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Charge and angular correlated inelasticities in MeV/nucleon ion-atom collisions

Using an Elbek high-resolution magnetic spectrograph, we measured energy loss an angular distributions of MeV/nucleon projectile ions in coincidence with target recoil-ion charge state. We investigated collisions of 10 and 20 MeV C/sup 6 +/ on He, Ne, Ar, and Kr where the target atom is multiply ionized and the projectile emerges in charge state q or q-1. The amount of energy transferred to the continuum electrons exceeds, by far, the sum of the values of the ionization potentials and shows a s… more

Date: November 8, 1988

Creator: Schoene, H.; Schuch, R.; Datz, S.; Dittner, P. F.; Giese, J. P.; Krause, H. F. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Production of autoionizing Rydberg states by transfer excitation in high energy ion atom collisions

The method of zero-degree Auger spectroscopy was used to study the production of autoionizing Rydberg states in collisions of carbon and oxygen projectiles incident at several MeV on He gas and carbon foils. The autoionization electrons were measured with high resolution so that the quantum defect corresponding to the angular momenta of the Rydberg electrons could be observed. The main purpose of the present experiment is to gain information about the n and l distribution of the Rydberg electro… more

Date: January 1, 1986

Creator: Stolterfoht, N.; Miller, P. D.; Krause, H. F.; Yamazaki, Y.; Dittner, P. F.; Pepmiller, P. L. et al.

Item Type: 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

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Surgery of fast, highly charged ions studied by zero-degree Auger spectroscopy

Zero-degree Auger spectra were measured in collisions of oxygen and carbon on He with incident charge states of q = 2 to 5 and for energies from 5 to 30 MeV. Since the light target particle He acts selectively on the projectile ion, we refer to the present method as ion surgery. Apart from the one-electron processes single excitation and single loss, two-electron processes such as transfer excitation and transfer loss are studied. 17 refs., 4 figs., 1 tab.

Date: January 1, 1986

Creator: Stolterfoht, N.; Miller, P. D.; Krause, H. F.; Yamazaki, Y.; Swenson, J. K.; Bruch, R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electron Transfer Processes in Collisions of Highly Charged Energetic (0.1 to 1.0 MeV/nucleon) Ions with Helium Atoms

We have investigated charge transfer in collisions of energetic (0.1 - 1 MeV/nucleon) highly charged ions with helium atoms with the principal aim clarifying the nature of two-electron processes. The sensitivity of partial charge-changing cross sections (i.e., single- and double-charge transfer, transfer ionization (TI), and single and double ionization) to core configuration and scaling rules for one- and two-electron processes were investigated with iodine ions (q = 5+ ..-->.. 26+) and uraniu… more

Date: January 1, 1987

Creator: Datz, S.; Hippler, R.; Andersen, L. H.; Dittner, P. F.; Knudsen, H.; Krause, H. F. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Electrons Emitted from 33-TeV Pb Ions During Penetration of Solids

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.

Item Type: Article

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

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: Report

Partner: UNT Libraries Government Documents Department

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L- and M-shell x-ray production cross sections of Nd, Gd, Ho, Yb, Au, and Pb by 25-MeV carbon and 32-MeV oxygen ions

Article discussing research on L- and M-shell x-ray production cross sections of Nd, Gd, Ho, Yb, Au, and Pb by 25-MeV carbon and 32-MeV oxygen ions.

Date: October 15, 1987

Creator: Andrews, M. C.; McDaniel, Floyd Del. (Floyd Delbert), 1942-; Duggan, Jerome L.; Miller, P. D.; Pepmiller, P. L.; Krause, H. F. et al.

Item Type: Article

Partner: UNT College of Arts and Sciences

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Transfer and excitation processes studied in H-like S and Li-like and H-like F colliding with H/sub 2/

We have studied transfer and simultaneous excitation by three different experimental techniques. Coincidences between two K x rays were measured for S/sup 15 +/, coincidences between one K x ray and the charge exchanged projectile for Li-like F and projectile Auger electrons for H-like F in each case colliding with H/sub 2/. For all three collision systems, the measured cross sections are dominated by Resonant Transfer and Excitation (RTE). Also, for the F projectiles, strong contributions from… more

Date: January 1, 1988

Creator: Schulz, M.; Datz, S.; Dittner, P. F.; Giese, J. P.; Krause, H. F.; Miller, P. D. et al.

Item Type: Article

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

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.

Item Type: Article

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)

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department