Berlin 2001 – scientific programme

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A: Atomphysik

A 10: Posters Wednesday (Cooling and Trapping, Electron Scattering and Recombination)

A 10.9: Poster

Wednesday, April 4, 2001, 12:30–15:00, AT3

The high resolution electron-ion collision facility at the TSR — •B. Lange¹, F. Sprenger¹, G. Wissler¹, M. Hoppe¹, U. Weigel¹, D. A. Orlov¹, A. S. Terekhov², D. Schwalm¹, and A. Wolf¹ — ¹Max Planck Institut für Kernphysik — ²Institute of Semiconductor Physics, Novosibirsk, Russia

Atomic and molecular ion beams circulating in a storage ring can be cooled translationally by interaction with superimposed colinear, cold electron beams at matched velocities. Many studies of the stored ions, on the other hand, involve electron interactions at non-zero relative energies in a wide range (meV to keV) with high energy resolution. In all storage rings so far both functions are met by switching the energy of a single electron beam device designed primarily for translational cooling (“electron cooler”). At the storage ring TSR, a high resolution electron target with a magnetically guided electron beam is being finalized. Operation simultaneous with the existing cooler will strongly improve the resolution, in particular at large interaction energies. Novel electron sources used are (a) cryogenic photocathodes and adiabatic acceleration for ultracold electron beams (transverse and longitudinal temperatures <1 meV and <0.05 meV, respectively) and (b) thermionic IrCe cathodes for high emission current density and hence large electron density at high interaction energies (≥10 keV); ongoing tests of the acceleration and collector assembly with IrCe cathodes will be presented. As detectors for recombination and ionization products and for molecular fragments, YAP:Ce scintillation detectors directly positioned in vacuum and optically connected to photomultiplies via light pipes are under test.