Abstract
By freezing out the motion between particles in a high-energy storage ring, it should be possible1,2,3,4 to create threads of ions, offering research opportunities beyond the realm of standard accelerator physics. The usual heating due to intra-beam collisions should completely vanish, giving rise to a state of unprecedented brilliance. Despite a continuous improvement of beam cooling techniques, such as electron cooling and laser cooling, the ultimate goal5 of beam crystallization has not yet been reached in high-energy storage rings. Electron-cooled dilute beams of highly charged ions show liquid-like order6,7 with unique applications8. An experiment5 using laser cooling9,10 suggested a reduction of intra-beam heating, although the results were ambiguous. Here we demonstrate the crystallization of laser-cooled Mg+ beams circulating in the radiofrequency quadrupole storage ring PALLAS11,12 at a velocity of 2,800 m s-1, which corresponds to a beam energy of 1 eV. A sudden collapse of the transverse beam size and the low longitudinal velocity spread clearly indicate the phase transition. The continuous ring-shaped crystalline beam shows exceptional stability, surviving for more than 3,000 revolutions without cooling.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Rent or buy this article
Get just this article for as long as you need it
$39.95
Prices may be subject to local taxes which are calculated during checkout
References
Parkhomchuk, V. in Crystalline Beams and Related Issues (eds Maletic, D. M. & Ruggiero, A. G.) 409–420 (World Scientific, Singapore, 1996).
Pestrikov, D. V. in Crystalline Beams and Related Issues (eds Maletic, D. M. & Ruggiero, A. G.) 275–294 (World Scientific, Singapore, 1996).
Schiffer, J. P. & Kienle, P. Could there be an ordered condensed state in beams of fully stripped heavy ions. Z. Phys. A 321, 181 (1985).
Rahman, A. & Schiffer, J. P. Structure of a one-component plasma in an external field. A molecular-dynamics study of particle arrangement in a heavy-ion storage ring. Phys. Rev. Lett. 57, 1133–1136 (1986).
Eisenbarth, U. et al. Anomalous behaviour of laser-cooled fast ion beams. Hyperfine Interact. 127, 223–235 (2000).
Steck, M. et al. Anomalous temperature reduction of electron-cooled heavy ion beams in the storage ring ESR. Phys. Rev. Lett. 77, 3803–3806 (1996).
Hasse, R. W. Theoretical verification of Coulomb order of ions in a storage ring. Phys. Rev. Lett. 83, 3430–3433 (1999).
Radon, T. et al. Schottky mass measurements of stored and cooled neutron-deficient projectile fragments in the element range of 57. Nucl. Phys. A 677, 75–99 (2000).
Lauer, I. et al. Transverse laser cooling of a fast stored ion beam through dispersive coupling. Phys. Rev. Lett. 81, 2052–2055 (1998).
Madsen, N. et al. Density limitations in a stored laser-cooled ion beam. Phys. Rev. Lett. 83, 4301–4304 (1999).
Schätz, T., Habs, D., Podlech, C., Wei, J. & Schramm, U. Towards crystalline ion beams—the PALLAS ring trap. in Proc. Workshop on Trapped Charged Particles and Fundamental Physics (eds Dubin, D. & Schneider, D.) AIP Conf. Proc. 457, 269–273 (1999).
Schramm, U., Schätz, T. & Habs, D. in Proc. Conf. on Appl. of Acc. in Research and Industry (eds Duggan, J. L.) AIP Conf. Proc. 576 (in the press).
Bryant, P. J. & Johnson, K. Circular Accelerators and Storage Rings (Cambridge Univ. Press, Cambridge, 1993).
Spreiter, Q., Seurer, M. & Toepffer, C. Relaxation in a strongly coupled particle beam. Nucl. Instrum. Methods A 364, 239–242 (1995).
Seurer, M., Spreiter, Q. & Toepffer, C. in Crystalline Beams and Related Issues (eds Maletic, D. M. & Ruggiero, A. G.) 311–328 (World Scientific, Singapore, 1996).
Raizen, M. G. et al. Ionic crystals in a linear Paul trap. Phys. Rev. A 45, 6493–6501 (1992).
Drewsen, M., Brodersen, C., Hornekaer, L., Hangst, J. S. & Schiffer, J. P. Large ion crystals in a linear Paul trap. Phys. Rev. Lett. 81, 2878–2881 (1998).
Birkl, G., Kassner, S. & Walther, H. Multiple-shell structures of laser-cooled Mg-ions in a quadrupole storage ring. Nature 357, 310–313 (1992).
Hasse, R. W. & Schiffer, J. P. The structure of the cylindrically confined Coulomb lattice. Ann. Phys. 203, 419–448 (1990).
Habs, D. & Grimm, R. Crystalline ion beams. Ann. Rev. Nucl. Part. Sci. 45, 391–428 (1995).
Schiffer, J. P. in Crystalline Beams and Related Issues (eds Maletic, D. M. & Ruggiero, A. G.) 217–228 (World Scientific, Singapore, 1996).
Wei, J., Okamoto, H. & Sessler, A. M. Necessary conditions for attaining a crystalline beam. Phys. Rev. Lett. 80, 2606–2609 (1998).
Blümel, R. et al. Phase transitions of stored laser-cooled ions. Nature 334, 309–313 (1988).
Dubin, D. H. E. First-order anharmonic correction to the free energy of a Coulomb-crystal in periodic boundary conditions. Phys. Rev. A 42, 4972–4982 (1990).
Schiffer, J. P., Drewsen, M., Hangst, J. & Hornekaer, L. Temperature, ordering, and equilibrium with time-dependent forces. Proc. Natl Acad. Sci. USA 97, 10697–10700 (2000).
Acknowledgements
We thank R. Neugart for technical support, and P. Kienle and H. Walther for discussions. The work was partially funded by the Deutsche Forschungsgemeinschaft and the Maier Leibmitz Labor.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Schätz, T., Schramm, U. & Habs, D. Crystalline ion beams. Nature 412, 717–720 (2001). https://doi.org/10.1038/35089045
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/35089045
This article is cited by
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
