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Research Activity Description (From the Yearbook 1993: New version Coming soon)


General Description In 1993 the Studies of Atomic collisions have been carried out by the following workers
  1. Johannes Mathias Hansteen, Professor
  2. Ladislav Kocbach, Associate Professor (førsteamanuensis)
  3. Jan Petter Hansen, Senior Research Fellow (forsker NAVF)
  4. Nikolai R. Toivonen, Visiting Scientist (Petrozavodsk, Russia)
and a varying number of research students. Two cand.scient. theses have been completed in 1993 (see the list).

Some years ago, the activity in the theory of atomic collisions has been directed mainly towards studies of inner shell ionization in asymmetric ion-atom collisions (Coulomb ionization), including the studies of relativistic effects and the role of the projectile deflection due to the target-projectile repulsion. More recently various other problems have been addressed, including electron transfer both in fast and slow collisions, collisions with nuclear contact and various geometrical aspects of collisions, such as alignment and orientation of the collision products.

The theoretical work is based both on analytical techniques and extensive use of computers to obtain numerical results. A large number of computer codes have been developed during the years, most recently a general two-centre expansion code for coupled channel calculations applicable to many different collisional regimes. In recent years much effort has been devoted to developement of techniques to visualize the dynamics of electronic motion in collisions using interactive computer graphics, in particular using computer animations of the electronic densities and probability density currents.

Much of the recent work has been done in collaborations supported by EC and Nordic Collaboration Projects. The research activities of the Bergen Group are closely related with reserchers at The Niels Bohr Institute in Copenhagen, The rsted Institute in Copenhagen, two groups at Universite de Paris V, Jussieu and Manne Siegbahn Institute at Stockholm. In addition to these there are many other collaborating groups joining the individual projects, as e.g. rhus, Freiburg, Wien, Debrecen, Prague and Petrozavodsk.

Research Activities in 1993. The various activities can be listed in the following way (when applicable, the location of collaborating group is given in parasntheses)

  1. Ionization caused by bombardment by slow antiprotons ( J.M. Hansteen and L. Kocbach)
  2. Electrodynamics of strong fields in the near symmetric collisions of the heaviest atoms ( J.M. Hansteen (Copenhagen))
  3. Charge exchange in slow and intermediate velocity collisions (J.P. Hansen Copenhagen and Paris)
  4. Investigation of the role of electron-electron interaction in Collisions (J.P. Hansen, L. Kocbach (Stockholm))
In addition to the studies of particular physical processes, there have also been more general investigation of new methodologies, based mostly on the use of computers in nontraditional ways:

  1. Use of Computer Algebra for Developement of Numerical Computer Codes (L. Kocbach (Prague))
  2. Use of Computer Algebra for Theoretical Analysis ( Toivonen and Kocbach)
  3. Use of Computer Graphics (L. Kocbach (Paris, Debrecen))

The following studies have been reported in international Journals (see the list of publications)

  1. K-shell ionization induced by slow proton and antiproton impact

  2. Electron capture from initialy aligned p-state atoms
  3. Electron capture from the light noble gases
  4. H-Na(3p) Collisions: Total and Differential Cross Sections for Electron Capture.
  5. Single and Double Electron Capture to Multiply Charged Ions Colliding with He
  6. Electron Capture by doubly charged ions from laser excited alkali atoms: He - Na(3p) collisions.
  7. Double atom excitation cross sections induced by the electron-electron interaction.
  8. Electron capture in ion-cluster collisions

Based on support from several sources, the Atomic Physics Group has built a Visualization Development Computer laboratory, where a broad range of computers is represented. The special advantage of this approach is that the software is developed across the various systems and can be used at collaborating laboratories who for various reasons preferred various computers. In the laboratory there are computers ranging from IBM PC compatible, over Apple Macintosh to Sun Sparcstation and HP-9000/720 workstations.

We have developed and tested a broad range of animation programs, running on all the mentioned computers with possibility to display the same data sets on all of them. On the smaller machines the visualizations are valuable mostly for presentations and pedagogical purposes, while at the workstations they are used as an integral part of our research.