First laser cooling of relativistic ions in a storage ring

Schröder, S.; Klein, Richard; Boos, Nikolaus; Gerhard, M.; Grieser, R.; Huber, G.; Karafillidis, A.; Krieg, M.; Schmidt, Nadine; Kühl, T.; Neumann, R.; Balykin, V. I.; Grieser, M.; Habs, D.; Jaeschke, E.; Krämer, D.; Kristensen, Martin; Mušič, M.; Petrich, Wolfgang; Schwalm, D.; Sigray, P.; Steck, M.; Wanner, B.; Wolf, A.

doi:10.1103/physrevlett.64.2901

Cited by 155 publications

(36 citation statements)

References 7 publications

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“…Among these methods, laser cooling is considered the most promising to achieve the lowest temperature, due to its very strong cooling force. The first laser-cooling experiment of an ion beam was carried out at Test Storage Ring (TSR) by Schröder et al [5], and followed at Aarhus Storage Ring in Denmark (ASTRID) by Hangst et al [6]. Both groups successfully cooled the longitudinal motion of coasting beams of heavy ions circulating at high speed in the laboratory frame; this technique was further extended for a bunched beam also in the ASTRID ring by Hangst et al [7].…”

Section: Introductionmentioning

confidence: 99%

Resonance coupling induced enhancement of indirect transverse cooling in a laser-cooled ion beam

Nakao

T.Hiromasa

Souda

et al. 2012

Phys. Rev. ST Accel. Beams

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We report the first observation of indirect resonantly enhanced transverse laser cooling of a bunched, stored ion beam of 40 keV 24 Mg þ . The longitudinal velocity distribution and the horizontal beam size of the laser-cooled 24 Mg þ ion beam with 280 nm laser light were simultaneously observed by the use of standard fluorescence-based techniques. Keeping the operation point at (2.068, 1.105), the synchrotron tune ( s ) was changed from 0.0376 to 0.1299. A strong decrease in the cooled horizontal beam size and a corresponding increase in the equilibrium cooled momentum spread were observed at the expected synchrobetatron resonance coupling condition of s ¼ 0:068, which is the first observation of a resonantly induced coupling for enhanced indirect transverse laser cooling of an ion beam, and is an important step towards creating a crystalline ground state of the beam.

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Section: Introductionmentioning

confidence: 99%

Resonance coupling induced enhancement of indirect transverse cooling in a laser-cooled ion beam

Nakao

T.Hiromasa

Souda

et al. 2012

Phys. Rev. ST Accel. Beams

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“…Measurements were repeated for successive injections over several hours. From earlier experiments [8] employing laser cooling of 7 Li + ions on the 2 3 S-2 3 P transition, a substantial initial fraction f 0 m ≈ 0.1-0.3 of metastable 2 3 S ions is known to exist in the TSR under these running conditions. The unknown initial fraction of metastable singlet (2 1 S) ions is expected to have decayed by the time the data were recorded.…”

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confidence: 99%

Dielectronic recombination of ground-state and metastable Li+ions

et al. 1999

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Dielectronic recombination has been investigated for ∆n = 1 resonances of ground-state Li + (1s 2 ) and for ∆n = 0 resonances of metastable Li + (1s2s 3 S). The ground-state spectrum shows three prominent transitions between 53 and 64 eV, while the metastable spectrum exhibits many transitions with energies < 3.2 eV. Reasonably good agreement of R-matrix, LS coupling calculations with the measured recombination rate coefficient is obtained. The time dependence of the recombination rate yields a radiative lifetime of 52.2 ± 5.0 s for the 2 3 S level of Li + .PACS number(s): 34.80. Lx, 32.70.Cs, 32.80.Dz In collisions between ions and electrons, recombination [1] can occur either by radiative recombination (RR) (inverse of the photoelectric effect), or by dielectronic recombination (DR). This process starts by the resonant capture of a free electron, mediated by its interaction with a bound electron (inverse of an Auger transition), and then proceeds by a radiative transition to a stable recombined system. Dielectronic recombination is of fundamental interest because it gives insight into electron correlation, and of applied interest for the understanding of astrophysical and laboratory plasmas. Extensive experimental studies providing significant tests of the theory [1] have been conducted for H-like, He-like, and Lilike ions heavier than about carbon. For such systems, perturbative techniques can be successfully used in theoretical calculations because the electron-electron interaction is relatively weak compared to the electron-nucleus interaction. In contrast, for lighter ions perturbative techniques cease to produce results at the same level of accuracy. Hence, high quality data for light systems are required to test the reliability of theoretical predictions.For the lightest H-like ion, He + , DR was studied previously by three groups [2-4] with successively higher energy resolution, and through a consequent feedback between experiment and theory good mutual agreement could be obtained. For the lightest He-like ion, Li + , the two-electron configuration places additional constraints on the theory of RR and DR. Moreover, the existence of relatively long-lived metastable 1s2s 1 S and 1s2s 3 S states with natural lifetimes of about 0.5 ms and 50 s, respectively, requires recombination for both the ground state and the metastable state (especially the long-lived triplet state) to be understood. To date, only lowresolution DR measurements for Li + have been carried out [5]; the integrated ground-state and metastable recombination rates could be extracted, but more detailed comparisons between experiment and theory for specific excited-state configurations were not possible.Here we report a high-resolution investigation of DR in Li + . Individual intermediate-excited state configurations contributing to DR could be resolved for groundstate Li + (1s 2 1 S) ions, where DR occurs via ∆n = 1 resonances (1s 2 + e → 1s2ln ′ l ′ ) at relative electron-ion energies of 53-64 eV, as well as for metastable Li + (1s2s 3 S)...

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“…At present, there exist only two storage rings in the world where laser cooling system has been installed; namely, the TSR ring [5] at MPI, Heidelberg, and the ASTRID ring [6] at Aarhus University, Denmark. However, these storage rings do not satisfy the necessary condition of crystal maintenance although with minor modifcations they would.…”

Section: Molecular Dynamics Resultsmentioning

confidence: 99%

Theory of tapered laser cooling

Okamoto¹,

Wei²

1998

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A theory of tapered laser cooling for fast circulating ion beams in a storage ring is constructed. We describe the fundamentals of this new cooling scheme, emphasizing that it might be the most promising way to beam crystallization. The cooling rates are analytically evaluated to study the ideal operating condition. We discuss the physical implication of the tapering factor of cooling laser, and show how to determine its optimum value. Molecular dynamics method is employed to demonstrate the validity of the present theory.

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First laser cooling of relativistic ions in a storage ring

Cited by 155 publications

References 7 publications

Resonance coupling induced enhancement of indirect transverse cooling in a laser-cooled ion beam

Resonance coupling induced enhancement of indirect transverse cooling in a laser-cooled ion beam

Dielectronic recombination of ground-state and metastable Li+ions

Theory of tapered laser cooling

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