D. Winters

HITRAP: A Facility at GSI for Highly Charged Ions

Abstract An overview and status report of the new trapping facility for highly charged ions at the Gesellschaft fur Schwerionenforschung is presented. The construction of this facility started in 2005 and is expected to be completed in 2008. Once operational, highly charged ions will be loaded from the experimental storage ring ESR into the HITRAP facility, where they are decelerated and cooled. The kinetic energy of the initially fast ions is reduced by more than fourteen orders of magnitude and their thermal energy is cooled to cryogenic temperatures. The cold ions are then delivered to a broad range of atomic physics experiments.

High-resolution measurement of the time-modulated orbital electron capture and of the β+ decay of hydrogen-like 142Pm60+ ions

Abstract The periodic time modulations, found recently in the two-body orbital electron capture (EC) decay of both, hydrogen-like 140Pr58+ and 142Pm60+ ions, with periods near to 7 s and amplitudes of about 20%, were re-investigated for the case of 142Pm60+ by using a 245 MHz resonator cavity with a much improved sensitivity and time resolution. We observed that the exponential EC decay is modulated with a period T = 7.11 ( 11 ) s , in accordance with a modulation period T = 7.12 ( 11 ) s as obtained from simultaneous observations with a capacitive pick-up, employed also in the previous experiments. The modulation amplitudes amount to a R = 0.107 ( 24 ) and a P = 0.134 ( 27 ) for the 245 MHz resonator and the capacitive pick-up, respectively. These new results corroborate for both detectors exactly our previous findings of modulation periods near to 7 s , though with distinctly smaller amplitudes. Also the three-body β + decays have been analyzed. For a supposed modulation period near to 7 s we found an amplitude a = 0.027 ( 27 ) , compatible with a = 0 and in agreement with the preliminary result a = 0.030 ( 30 ) of our previous experiment. These observations could point at weak interaction as origin of the observed 7 s -modulation of the EC decay. Furthermore, the data suggest that interference terms occur in the two-body EC decay, although the neutrinos are not directly observed.

Probing nuclear properties by resonant atomic collisions between electrons and ions

The utilization of the resonant atomic electron–ion collision process of dielectronic recombination (DR) as a tool to probe nuclear properties via isotope shifts and hyperfine effects is discussed. Based on DR, this resonance reaction spectroscopy at electron coolers of heavy-ion storage rings denotes a versatile approach to access nuclear parameters such as charge radius, spin, magnetic moment or lifetimes of long-lived excited nuclear states (isomers). The high sensitivity of DR allows for experiments with artificially synthesized rare isotopes and isomers. Recent experimental progress in the preparation of such exotic species at the ESR storage ring in Darmstadt is presented. The DR technique is exemplified for the case of 234Pa88+ (Z = 91).

SPARC: The Stored Particle Atomic Research Collaboration At FAIR

The future international accelerator Facility for Antiproton and Ion Research (FAIR) encompasses 4 scientific pillars containing at this time 14 approved technical proposals worked out by more than 2000 scientists from all over the world. They offer a wide range of new and challenging opportunities for atomic physics research in the realm of highly‐charged heavy ions and exotic nuclei. As one of the backbones of the Atomic, Plasma Physics and Applications (APPA) pillar, the Stored Particle Atomic Physics Research Collaboration (SPARC) has organized tasks and activities in various working groups for which we will present a concise survey on their current status.

Isotope shifts in dielectronic recombination: From stable to in-flight-produced nuclei

The study of isotope shifts and hyperfine effects in dielectronic recombination (DR) resonance spectra strikes a conceptually new path for investigations of nuclear properties such as charge radius, spin, magnetic moment of nuclei or lifetimes of long-lived excited nuclear states. A series of DR experiments with heavy three-electron ions (Li-like) was performed at the heavy-ion storage ring ESR of the GSI Helmholtzzentrum fur Schwerionenforschung, Darmstadt, Germany. In a pilot experiment the two stable isotopes A=142 and A=150 of neodymium ANd57+ were investigated. From the displacement of DR resonances the isotope shifts δE142,150(2s – 2Pl/2) = 40.2(3)(6) meV and δE142,150(2s – 2p3/2) = 42.3(12)(20) meV for 2s – 2Pj transitions of the Li-like ions have been obtained. An evaluation within a full QED framework yielded a change in the mean-square charge radius of 142,150δ(r2) = −1.36(1)(3) fm2. At GSI, in addition to stable isotopes, in-flight synthesized radioisotopes can be studied as well. The production of radioisotopes of interest, the subsequent separation in the storage ring ESR and first DR experiments with the exotic nuclei 237U89+ and 234Pa88+ (Z=91) are presented. The paper is concluded with a brief outlook at future DR experiments with heavy radioisotopes at the ESR.

First observation of the ground-state hyperfine transition in 209Bi80+

The long sought after ground-state hyperfine transition in lithium-like bismuth 209Bi80+ was observed for the first time using laser spectroscopy on relativistic ions in the experimental storage ring at the GSI Helmholtz Centre in Darmstadt. Combined with the transition in the corresponding hydrogen-like ion 209Bi82+, it will allow extraction of the specific difference between the two transitions that is unaffected by the magnetic moment distribution in the nucleus and can therefore provide a better test of bound-state QED in extremely strong magnetic fields.

First measurement of the 96Ru( p,γ )97Rh cross section for the p process with a storage ring

This work presents a direct measurement of the

Beta decay of highly charged ions

^{96}

Observation of the 2p3/2→2s1/2 intra-shell transition in He-like uranium

Ru(

Prospects for laser spectroscopy of highly charged ions with high-harmonic XUV and soft x-ray sources

p, \gamma