| 1. |
- Böhm, S, et al.
(författare)
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Enhancement of dielectronic recombination by external electromagnetic fields
- 2003
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Ingår i: Hyperfine Interactions. - 0304-3843. ; 146-147:1-4, s. 23-27
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Tidskriftsartikel (refereegranskat)abstract
- The enhancement of the dielectronic recombination rate of lithiumlike Ne7+ and O5+ ions by external electromagnetic fields has been measured at the storage ring CRYRING. The energy range covered all 1s(2)2pnl dielectronic recombination resonances attached to the 2s --> 2p core excitation. Electric fields up to 1436 V/cm were applied in the Ne7+ experiment and the saturation of the enhancement with increasing electric field could clearly be seen. In the O5+ experiment the enhancement was studied as a function of the Rydberg quantum number n.
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| 2. |
- Böhm, S, et al.
(författare)
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Influence of electromagnetic fields on the dielectronic recombination of Ne7+ and O5+ ions
- 2001
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Ingår i: Physica Scripta. Topical Issues. - 0281-1847. ; T92, s. 395-397
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Tidskriftsartikel (refereegranskat)abstract
- Within a series of measurements of the dielectronic recombination (DR) of lithium-like ions we have determined the enhancement of the recombination rate in the presence of crossed electric and magnetic fields for Ne7+ and O5+ ions. In both cases the electron energy range covers a DR resonances attached to 2s --> 2p(1/2) and 2s --> 2p(3/2) Delta_n = 0 core excitations. For increasing field the enhancement factor first increases linearly with the electric field and then saturates. In order to investigate the field effect on high-n Rydberg states the ion energy in the O5+ experiment was changed from 9.4 MeV/u to 5 MeV/u and 3.26 MeV/u. With the variation of the ion energy the field ionization of Rydberg states in the analyzing magnet is influenced. This enabled us to study the field enhancement for a narrow bandwidth of n-states.
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| 3. |
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| 4. |
- Glans, Peter, et al.
(författare)
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Dielectronic recombination used as a tool for spectroscopic studies of highly charged ions
- 2004
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Ingår i: Physica scripta. T. - 0281-1847. ; T110, s. 212-215
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Tidskriftsartikel (refereegranskat)abstract
- Systematic studies of electron-ion recombination for Li-like, Na-like, and Cu-like ions have been made during the last few years at the CRYRING facility. The main purpose has been to measure recombination spectra with such high resolution and accuracy that stringent tests of advanced atomic calculations of doubly excited states can be made. From the comparison with theory it is possible to obtain energy positions, as well as radiative and nonradiative decay rates for the doubly excited states. In addition, for heavy, highly charged ions it is possible to deduce radiative corrections for energy splittings with very high accuracy.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Böhm, S, et al.
(författare)
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Influence of electromagnetic fields on the dielectronic recombination of Ne7+ ions
- 2001
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947. ; 64:3, s. 032707/1-032707/7
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Tidskriftsartikel (refereegranskat)abstract
- The influence of crossed electric and magnetic fields on dielectronic recombination of Ne7+ ions has been measured at the Stockholm heavy-ion storage ring CRYRING. The electron energy range covered all dielectronic recombination resonances attached to 2s-2p1/2 and 2s-2p3/2 core excitations. Two sets of measurements at magnetic fields of 180 mT and 30 mT have been performed. For the measurement at 180 mT we applied 25 different electric fields between 0 and 1400 V/cm. The resonance strength for dielectronic recombination via high Rydberg states initially increases linearly with electric field and later levels out. At a magnetic field of 30 mT we applied 15 different electric fields ranging from 0 to 140 V/cm. Compared to the measurement at 180 mT the initial slope of the rate enhancement was larger by almost a factor of 2. The fraction of resonant strength not measured due to field ionization is estimated by a model calculation of dielectronic recombination cross sections.
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| 9. |
- Eklöw, N, et al.
(författare)
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Magnetic-field dependence in electron-deuteron recombination at very low relative energy
- 2000
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Ingår i: Hyperfine Interactions. - 0304-3843 .- 1572-9540. ; 127:1-4, s. 251-255
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Tidskriftsartikel (refereegranskat)abstract
- The rate coefficient for recombination of D+ with low-energy electrons has been measured at different magnetic fields in the interaction region of the electron cooler at CRYRING. It is found that the measured recombination rate coefficient is influenced by the magnetic field.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Fritioff, Tomas, et al.
(författare)
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Shedding light on the Mercury Mass Discrepancy by weighing Hg52+ ions in a Penning trap
- 2003
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Ingår i: Nuclear Physics A. - : Elsevier Science B.V.. - 0375-9474 .- 1873-1554. ; 723:1-2, s. 3-16
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Tidskriftsartikel (refereegranskat)abstract
- In their nuclear tables Audi and Wapstra have pointed out a serious mass discrepancy between their extrapolated values for the mercury isotopes and those from a direct measurement by the Manitoba group. The values deviate by as much as 85 ppb from each other with claimed uncertainties of about 16 and 7 ppb, respectively. In order to decide which values are correct the masses of the 198Hg and 204Hg isotopes have been measured in the Stockholm Penning trap mass spectrometer SMILETRAP using 52+ ions. This charge state corresponds to a filled Ni electron configuration for which the electron binding energy can be accurately calculated. The mass values obtained are 197.966 768 44(43) u for 198Hg and 203.973 494 10(39) u for 204Hg. These values agree with those measured by the Manitoba group, with a 3 times lower uncertainty. This measurement was made possible through the implementation of a cooling technique of the highly charged mercury ions during charge breeding in the electron beam ion source used for producing the Hg52+ ions.
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| 14. |
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| 15. |
- Schuch, R, et al.
(författare)
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High resolution studies of electron-ion recombination
- 2003
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Ingår i: Radiation Physics and Chemistry. - 0969-806X. ; 68:1-2, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- The formation of atoms by recombination of free electrons with ions is a fundamental process and plays a central role in astro-physical and fusion plasmas. It can be seen as time-inverse photo-ionization, auto-ionization, or electron-impact ionization. Here, we show how these processes can be measured with cooler-storage rings, such as CRYRING at MSL, with very high accuracy. The status of theoretical modeling is briefly reviewed and anomalies are uncovered. We discuss some examples of recombination for ions where strong dielectronic recombination resonances occur. With cooler-storage rings, these resonances can today be measured with meV accuracy, and from the spectra of the dielectronic resonances, very accurate values for energy splittings and resonance strengths are derived. These allow crucial tests of relativistic, correlation, and QED effects in these systems.
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| 16. |
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| 17. |
- Tokman, M, et al.
(författare)
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Accurate calculations on dielectronic recombination resonances in Cu-like Pb
- 2001
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Ingår i: Hyperfine Interactions. - 0304-3843. ; 132:1-4, s. 383-389
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Tidskriftsartikel (refereegranskat)abstract
- Dielectronic recombination of Pb53+ has been studied and a resonance is detected only similar to 0.1 meV above the ground state. The possibility to determine the 4p(1/2) - 4s(1/2) energy splitting with a similar accuracy from the determination of the resonance position is discussed. Such a precision can only be achieved by calculations which treat QED in a many-body environment at levels which can still not be reached. A fully relativistic many-body calculation of the splitting is described and the uncertainties are discussed.
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| 18. |
- Tokman, M, et al.
(författare)
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Dielectronic recombination resonances in F6
- 2002
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 1050-2947. ; 66:1, s. 012703/1-012703/13
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Tidskriftsartikel (refereegranskat)abstract
- Electron-ion recombination spectra of the Li-like ion F6+ in the energy range 0.0-0.6 eV from two different ion storage rings are presented, showing excellent agreement. The experimental results are compared with a calculated spectrum, obtained by combination of relativistic many-body methods and complex rotation, and the agreement is found to be very good. The recombination spectrum in the studied energy region is determined by the 2p6l dielectronic recombination resonances. The lowest-energy resonances are found around 10 meV, and include one broad resonance overlapping the threshold. The recombination rate coefficients are, even in this region, very well accounted for by the calculation. It is further shown that the nonrelativistically allowed resonances contribute to less than 60% of the integrated rate coefficients in the specified energy range.
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| 19. |
- Tokman, M, et al.
(författare)
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Towards a determination of QED effects in Cu-like Pb recombination resonances near threshold
- 2001
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Ingår i: Physica Scripta. Topical Issues. - 0281-1847. ; T92, s. 406-409
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Tidskriftsartikel (refereegranskat)abstract
- Dielectronic recombination of Pb53+ has been studied and a resonance is detected only similar to 10(-4) eV above the ground state. The possibility to determine the Pb53+ (4p(1/2)) - Ph53+ (4s(1/2)) energy splitting with a similar accuracy from the determination of the resonance position is discussed. Such a precision can only be achieved by calculations which treat quantum electrodynamics (QED) in a many-body environment at a level which can still not be reached. A fully relativistic many-body calculation of the splitting is described and the uncertainties are discussed.
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