Publications (34)23.63 Total impact
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Article: High-precision laser-assisted absolute determination of x-ray diffraction angles.
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ABSTRACT: A novel technique for absolute wavelength determination in high-precision crystal x-ray spectroscopy recently introduced has been upgraded reaching unprecedented accuracies. The method combines visible laser beams with the Bond method, where Bragg angles (θ and -θ) are determined without any x-ray reference lines. Using flat crystals this technique makes absolute x-ray wavelength measurements feasible even at low x-ray fluxes. The upgraded spectrometer has been used in combination with first experiments on the 1s2p(1)P(1) → 1s(2)(1)S(0) w-line in He-like argon. By resolving a minute curvature of the x-ray lines the accuracy reaches there the best ever reported value of 1.5 ppm. The result is sensitive to predicted second-order QED contributions at the level of two-electron screening and two-photon radiative diagrams and will allow for the first time to benchmark predicted binding energies for He-like ions at this level of precision.The Review of scientific instruments 01/2012; 83(1):013102. · 1.52 Impact Factor -
Article: Two-loop QED contributions tests with mid-Z He-like ions
Journal of Physics: …. 01/2009; -
Article: Single-electron capture in keV Ar15+...18++He collisions
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ABSTRACT: Export Date: 23 October 2011, Source: Scopus, Art. No.: 195203, CODEN: JPAPE, doi: 10.1088/0953-4075/41/19/195203Journal of Physics B: Atomic, Molecular and Optical Physics. 01/2008; 41. -
Article: Testing QED screening and two-loop contributions with He-Like ions.
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ABSTRACT: We report wavelength measurements of H-like and He-like ions obtained with a novel x-ray spectrometer at the Heidelberg Electron Beam Ion Trap. The experimental uncertainty for the Lyman-alpha1 wavelength in Cl16+ is reduced by a factor of 3 and, as expected, excellent agreement with theory is maintained. For the resonance line in He-like Ar16+, an uncertainty of only deltalambda/lambda=2x10(-6) was achieved. This is the most precise x-ray wavelength reported for highly charged ions to date, and allows to test recent predictions on QED two-electron and two-photon radiative corrections for He-like ions. The results also point to the advantages of establishing absolute x-ray wavelength standards using Lyman-alpha transitions (in the present case Ar17+ Lyman-alpha1) to supersede the current ones.Physical Review Letters 10/2007; 99(11):113001. · 7.37 Impact Factor -
Article: Testing QED Screening and Two-Loop Contributions with He-Like Ions
Physical review letters. 01/2007; -
Article: High precision X-ray spectroscopy on H-and He-like Argon Ions
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ABSTRACT: Export Date: 23 October 2011, Source: Scopus, Art. No.: 012016, doi: 10.1088/1742-6596/72/1/012016Journal of Physics: Conference Series. 01/2007; 72. -
Article: Testing QED screening and two-loop contributions with He-like ions
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ABSTRACT: Cited By (since 1996): 10, Export Date: 23 October 2011, Source: Scopus, Art. No.: 113001, CODEN: PRLTA, doi: 10.1103/PhysRevLett.99.113001Physical Review Letters. 01/2007; 99. -
Article: Benchmarking high-field few-electron correlation and QED contributions in Hg^{75+} to Hg^{78+} ions. I. Experiment
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ABSTRACT: The photorecombination of highly charged few-electron mercury ions Hg75+ to Hg78+ has been explored with the Heidelberg electron beam ion trap. By monitoring the emitted x rays (65–76 keV) and scanning the electron beam energy (45–54 keV) over the KLL dielectronic recombination (DR) region, the energies of state-selected DR resonances were determined to within ±4 eV (relative) and ±14 eV (absolute). At this level of experimental accuracy, it becomes possible to make a detailed comparison to various theoretical approaches and methods, all of which include quantum electrodynamic (QED) effects and finite nuclear size contributions (for a 1s electron, these effects can be as large as 160 and 50 eV, respectively). In He-like Hg78+, a good agreement between the experimental results and the calculations has been found. However, for the capture into Li-, Be-, and B-like ions, significant discrepancies have been observed for specific levels. The discrepancies suggest the need for further theoretical and experimental studies with other heavy ions along these isoelectronic sequences.Phys. Rev. A. 05/2006; 73(5). -
Article: Lifetime measurement of the Ar XIV 1s^2 2s^2 2p^2 P_ 3∕ 2^o metastable level at the Heidelberg electron-beam ion trap
Physical Review A. 01/2006; -
Article: Lifetime measurement of the Ar XIV 1s sup 2 2s sup 2 2p sup 2 P sub 3/2sup o metastable level at the Heidelberg electron-beam ion trap
Physical Review. A. 01/2006; -
Article: Lifetime measurement of the Ar XIV 1 s2 2 s2 2p P 3/2 o2 metastable level at the Heidelberg electron-beam ion trap
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ABSTRACT: Cited By (since 1996): 11, Export Date: 23 October 2011, Source: Scopus, Art. No.: 052507, CODEN: PLRAA, doi: 10.1103/PhysRevA.73.052507Physical Review A - Atomic, Molecular, and Optical Physics. 01/2006; 73. -
Article: Relativistic electron correlation, quantum electrodynamics, and the lifetime of the 1s(2)2s(2)2p2p0(3/2) level in boronlike argon.
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ABSTRACT: The lifetime of the Ar13+ 1s(2)2s(2)2p2p0(3/2) metastable level was determined at the Heidelberg Electron Beam Ion Trap to be 9.573(4)(5). The accuracy level of one per thousand makes this measurement sensitive to quantum electrodynamic effects like the electron anomalous magnetic moment (EAMM) and to relativistic electron-electron correlation effects like the frequency-dependent Breit interaction. Theoretical predictions, adjusted for the EAMM, cluster about a lifetime that is approximately shorter than our experimental result.Physical Review Letters 11/2005; 95(18):183001. · 7.37 Impact Factor -
Article: State-selective quantum interference observed in the recombination of highly charged Hg 75+...78+ mercury ions in an electron beam ion trap.
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ABSTRACT: We present experimental data on the state-selective quantum interference between different pathways of photorecombination, namely, radiative and dielectronic recombination, in the KLL resonances of highly charged mercury ions. The interference, observed for well resolved electronic states in the Heidelberg electron beam ion trap, manifests itself in the asymmetry of line shapes, characterized by "Fano factors," which have been determined with unprecedented precision, as well as their excitation energies, for several strong dielectronic resonances.Physical Review Letters 06/2005; 94(20):203201. · 7.37 Impact Factor -
Article: Do Electrons and Ions Coexist in an EBIT?
Physics with Ultra Slow …. 01/2005; -
Article: Novel technique for high-precision Bragg-angle determination in crystal x-ray spectroscopy
Review of scientific …. 01/2005; -
Article: State-selective quantum interference observed in the recombination of highly charged Hg 75 + 78 + mercury ions in an electron beam ion trap
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ABSTRACT: Cited By (since 1996): 34, Export Date: 23 October 2011, Source: Scopus, Art. No.: 203201, CODEN: PRLTA, doi: 10.1103/PhysRevLett.94.203201Physical Review Letters. 01/2005; 94. -
Article: High precision measurements of forbidden transitions in highly charged ions at the Heidelberg EBIT
Nuclear Instruments and …. 01/2005; -
Article: Relativistic electron correlation, quantum electrodynamics, and the lifetime of the 1s22s22pP3/2o2 level in boronlike argon
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ABSTRACT: Cited By (since 1996): 32, Export Date: 23 October 2011, Source: Scopus, Art. No.: 183001, CODEN: PRLTA, doi: 10.1103/PhysRevLett.95.183001Physical Review Letters. 01/2005; 95:1-4. -
Article: Progress at the heidelberg ebit
Journal of Physics: …. 01/2004; -
Article: Optimization of the charge state distribution of the ion beam extracted from an EBIT by dielectronic recombination
Review of scientific …. 01/2004;
Top Journals
Institutions
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2006–2012
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Max-Planck-Institut für Kernphysik
Heidelberg, Baden-Wuerttemberg, Germany
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2005
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University of California, Berkeley
- Department of Physics
Berkeley, MO, USA
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