Bulletin of the American Physical Society
39th Annual Meeting of the APS Division of Atomic, Molecular, and Optical Physics
Volume 53, Number 7
Tuesday–Saturday, May 27–31, 2008; State College, Pennsylvania
Session C3: Ion and Electron Collisions |
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Chair: Horst Schmidt-Boecking, University of Frankfurt Room: Keller Building 104 |
Wednesday, May 28, 2008 2:00PM - 2:36PM |
C3.00001: Experiments with Reaction Microscopes in ion storage rings - first results and prospects Invited Speaker: Reaction Microscopes became a standard tool to study the dynamics of atomic and molecular break-up processes. They enable measurements of kinematically complete data sets by momentum resolved and coincident detection of all target fragments produced in single collisions with electrons, ions, single photons, or in strong laser fields. Here we report on the first operation of a Reaction Microscope in a heavy-ion storage ring, the ESR at GSI in Darmstadt (Germany). The ESR provides excellent experimental conditions w.r.t intensity and emittance of the ion beam and thus, in combination with a Reaction Microscope, represents the ideal tool to obtain highly differential information on fundamental HCI-atom collision processes. The results of first experiments on target ionization and charge transfer in collisions of highly charged projectiles ranging from 13 AMeV U$^{92+}$ to 400 AMeV Ni$^{28+}$ with He, Ne, and Ar targets will be presented. Future experiments are planned to study e.g. radiative and non-radiative charge transfer reactions where also photons are detected in coincidence. Furthermore, simultaneous ionization of target and projectile shall be investigated to obtain insight into the dynamics of collision induced electron emission from HCIs. [Preview Abstract] |
Wednesday, May 28, 2008 2:36PM - 3:12PM |
C3.00002: Polarization and Angular Correlation of X-Rays Emitted in Relativistic Ion-Atom Collisions Invited Speaker: Particle and photon polarization phenomena occurring in collisions of relativistic ions with matter have recently attracted a lot of interest. In particular, investigations on the emitted characteristic x-ray and radiative electron capture (REC) radiation has been found a versatile tool for probing our present understanding of the dynamics of particles in extreme electromagnetic fields. For the 2p$_{3/2}\to $1s$_{1/2 }$transition of H-like U$^{91+}$ ions, for example, the interference between the electric-dipole (E1) and magnetic-quadrupole (M2) lines were found to affect considerably the measured angular distribution and to resolve the discrepancy between experiment and theory. Owing to the progress in x-ray detector techniques, in addition, measurements of the polarization of the REC photons became possible and enable one today to derive information about the polarization of the ion beams. In this talk, we review the recent experimental and theoretical progress on the (correlated) capture and decay processes of high-Z ions. Examples include (i) the angular distribution and polarization of the recombination and subsequent photons, (ii) the alignment of the (excited) levels as well as (iii) interferences due to magnetic multipoles. It is shown that the properties of the incident ions (and electrons) can be analyzed by means of the emitted x-ray radiation. [Preview Abstract] |
Wednesday, May 28, 2008 3:12PM - 3:48PM |
C3.00003: Contemporary Methods and New Phenomena in Atomic Collisions Invited Speaker: In recent years, with the increasing availability of powerful high performance computers, the direct numerical solution of time-dependent Schrodinger equation has become a desirable theoretical technique for investigating atomic and molecular collision processes. This quantitative and rigorous approach has been applied to solve various non-perturbative problems such as in electron-impact ionization, photoionization, heavy particle collision processes and laser-matter interactions. In this talk, we focus on ion collisions with ions and atoms. We review our recent theoretical advancements and latest calculations for a wide range of inelastic processes, ranging from charge transfer, excitation and ionization cross sections to ejected electron momentum spectra to vortex creation and dynamics in time-dependent potential fields. [Preview Abstract] |
Wednesday, May 28, 2008 3:48PM - 4:24PM |
C3.00004: Correlated Electronic Dynamics in Ion-Atom Collisions Invited Speaker: In this talk, I will examine the correlated electronic dynamics that occur during single and double ionization of helium by ion impact. A non-perturbative time-dependent close-coupling method (TDCC) is applied to fully describe the interaction between the outgoing ionized electrons. Also, the projectile-atom interaction is constructed as a multipole expansion that includes monopole, dipole, quadrupole, and octopole terms. Excellent agreement is obtained between our TDCC calculations and experimental measurements for single and double ionization cross sections for antiproton impact of helium. At an impact energy of 1 MeV we find that the double-to-single ionization ratio is twice as large for antiproton impact as for proton impact, confirming a long-standing unexpected experimental measurement. I will also report on our progress towards fully differential cross sections for 6 MeV proton impact double ionization of helium. [Preview Abstract] |
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