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A: Atomphysik

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

A 10.35: Poster

Mittwoch, 4. April 2001, 12:30–15:00, AT3

Storage rings measurement of the dielectronic recombination of beryllium-like Cl¹³⁺ and Cu²⁵⁺ ions — •M. Schnell¹, M. Bannister², G. Gwinner¹, S. Kieslich³, A. Müller³, S. Schippers³, D. Schwalm¹, and A. Wolf¹ — ¹Max-Planck-Institut für Kernphysik — ²Oak Ridge National Laboratory, USA — ³Institut für Kernphysik, Universität Giessen

At the Heidelberg heavy ion storage ring TSR we have measured in high resolution the dielectronic recombination (DR) rate coefficients for Cl¹³⁺ and Cu²⁵⁺ ions. The electron-ion center-of-mass energies ranged from zero up to beyond the series limits associated with 2s²→ 2s2p excitations of the berylliumlike core. Rydberg series of DR resonances 2s2p(^1,3P)nl attached to singlet and triplet series limits have been identified (n down to 7 for Cl¹³⁺ and 9 for Cu²⁵⁺). Some resonances in the DR spectra, however, remain unidentified. A check whether these resonances arise from DR on metastable 2s2p ³P₀ ions in the primary beam has been performed by varying the storage time of the ions prior to the DR measurement, yielding a negative result. The calibration of the center-of-mass energy scale was improved by measuring the electron-cooler voltage in real time during the experiment. With this method the resulting Rydberg series limits of Cu²⁵⁺ deviate from optical spectroscopic data by no more than a tenth of a percent. This is a significant improvement of the energy calibration for electron-ion recombination spectra.