Resonant Recombination at Ion Storage Rings: A Conceptual Alternative for Isotope Shift and Hyperfine Studies


Sharp resonant structures in the cross section of the atomic electron-ion collision process of dielectronic recombination are exploited to study isotope shifts and hyperfine interaction of heavy highly-charged ions. This novel approach provides a conceptual alternative to existing methods. In this contribution, we present a series of measurements, which we performed at the heavy ion storage ring ESR of the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. In a first experiment the stable isotopes A = 142 and A = 150 of three-electron neodymium ANd57+ were studied. Isotope shifts of dielectronic resonances associated with 2s - 2pj (j = 1/2, 3/2) transitions were extracted from the measured data. The evaluation of the energy shift was performed within a full QED framework and yielded a change in the mean-square charge radius of 142,150δ〈r2〉 = -1.36(1)(3) fm2. At GSI, in addition to the investigation of stable isotopes unstable species can be artificially synthesized and studied. Radioisotopes produced in-flight from fragmentation of a 238U primary beam were injected into the ESR and were subsequently separated by their mass-to-charge ratio. This enabled us to perform first DR experiments with the exotic nuclei 237U89+ (Z = 92) and 234Pa88+ (Z = 91).



Keywords and Phrases

Dielectronic Recombination; Hyperfine Interaction; Isotope Shift; Storage Ring

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Article - Journal

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Publication Date

01 Feb 2010