Hannover 2003 – wissenschaftliches Programm

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A: Atomphysik

A 11: Postersitzung 1

A 11.23: Poster

Dienstag, 25. März 2003, 16:00–18:30, Poster

Multi-electron capture from cold Na atoms — •Steven Knoop, Annemieke Hendrickx, Reinhard Morgenstern, and Ronnie Hoekstra — KVI, Atomic Physics, Rijksuniversiteit Groningen, Zernikelaan 25, NL 9747 AA Groningen, The Netherlands

We study collisions between low energy ions and ultra-cold Na atoms, using the techniques of Magneto-Optical Trapping and Recoil Ion Momentum Spectroscopy (MOTRIMS) [1-3]. By measuring the minute recoil momenta of the target ions, detailed information about ion-atom collision can be obtained.

Last year we designed and built a new apparatus. The drift region has been enlarged to obtain longer flight times and three rings before the entrance of the drift region assure the possibility of simultaneously time and spatial focusing. Simulations show that this should lead to an improvement in resolution with a factor of 5-10 (< 1 eV), meaning that state selective measurements would become feasible.

We plan to present new higher-resolution experimental results, especially on multi-electron capture processes in He²⁺-Na collisions at keV energies. For this collision we found evidence in previous experiments that besides true electron capture processes, ionization plays a role as well, leading to the creation of Na³⁺ recoils. Resolving the final state of Na³⁺ recoils would for instance reveal how electron spin is conserved in multi-electron processes.

[1] J. W. Turkstra, et al., Phys. Rev. Lett. 87, 123202 (2001).

[2] M. v. d. Poel et al., Phys. Rev. Lett. 87, 123201 (2001).

[3] X. Flèchard et al., Phys. Rev. Lett. 87, 123203 (2001).