German Title: Lasergekühlte Atome als Präzisionstarget für den Schwerionenspeicherring TSR

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Translation of abstract (English)

A target based on ultracold cesium atoms confined in a magneto-optical trap (MOT) has been installed inside the Heidelberg Test Storage Ring TSR. Since the trapped atoms are very well localized and their thermal energy can be neglected they are ideally suited to study collisions with stored heavy ions at energies of some MeV/u. Measurements of collision cross sections for ionization of the target atoms are carried out and the results are compared to theoretical predictions. Additionally, the transfer of electrons from the target atom to the projectile ion is investigated. Inner shell vacancies produced in the capture process are filled by Auger-cascades and shake-off processes. Therefore, the cesium is ionized to several charge states. The charge states are resolved by time-of-flight measurements. From the TOF spectra the momentum transfer to the recoiled cesium ion is determined. As an additional application the trapped atoms are used to measure the two-dimensional density distribution of the stored ions. This method is of great interest for very dilute beams because reliable measurements down to very low ion currents in the order of 10 nA become possible. The resolution of this method is only limited by the size of the atom cloud (actual diameter: some 100 µm). Thus, the resolution is better than resolution of the restgas beam profile monitor at TSR.