Couplage entre un piège magnéto-optique et un spectromètre d'impulsion d'ions de recul ; applications aux collisions ions-atomes

Abstract : 87Rb atoms have been cooled, trapped and prepared as targets for collision studies with 2 and 5 keV Na+ projectiles. The physics studied deals with charge exchange processes. The active electron, which is generally the most peripheral electron of the atomic target, is transferred from the target onto the ionic projectile. The ionized target is called recoil ion. The technique used to study this physics is the MOTRIMS technique, which combines a magneto optical trap and a recoil ion momentum spectrometer. The spectrometer is used for the measurement of the recoil ions momentum, which gives access to all the information of the collision: the Q-value (which is the potential energy difference of the active electron on each particle) and the scattering angle of the projectile. The trap provides extremely cold targets to optimize the measurement of the momentum, and to release the latter from thermal motion. Through cinematically complete experiments, the MOTRIMS technique gives access to better resolutions on momentum measurements. Measurements of differential cross sections in initial and final capture states and in scattering angle have been done. Results obtained for differential cross sections in initial and final states show globally a good agreement with theory and an other experiment. Nevertheless, discrepancies with theory and this other experiment are shown for the measurements of doubly differential cross sections. These discrepancies are not understood yet. The particularity of the experimental setup designed and tested in this work, namely a low background noise, allows a great sensitivity to weak capture channels, and brings a technical and scientific gain compared with previous works.
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Submitted on : Tuesday, November 18, 2008 - 10:00:04 AM
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J. Blieck. Couplage entre un piège magnéto-optique et un spectromètre d'impulsion d'ions de recul ; applications aux collisions ions-atomes. Physique Atomique [physics.atom-ph]. Université de Caen, 2008. Français. ⟨tel-00339513⟩

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