Laser cooling of stored ions in ASTRID : a storage ring for ions and electrons

J. S. Hangst,¹ K. Berg-Sørensen, P. S. Jessen, M. Kristensen, K. Mølmer, J. S. Nielsen, O. Poulsen, J. P. Schiffer² and P. Shi

1. Institute of Physics and Astronomy, University of Aarhus, DK-8000 Århus, C Denmark
2. Søren Pape Møller Institute for Synchrotron Radiation, University of Aarhus, DK-8000 Århus, C Denmark
 

A small storage ring, ASTRID, for ions and electrons has been constructed. It is a dual-purpose machine, serving as a storage ring for either ions or electrons for synchrotron-radiation production. The ring has for more than one year been operational with ions and has recently been commissioned for electron storage. Both these running modes will be described as well as results given from the first experiments with laser cooled ions. Finally, prospectsfor experimentswith superhigh mass and isotope selectivity will be discussed.
 

Back | Full Text

Observation of Quantized Motion of Rb Atoms in an Optical Field

P. S. Jessen, C. Gerz, P. D. Lett, W. D. Phillips, S. L. Rolston, R. J. C. Spreeuw and C. I. Westbrook

National Institute of Standards and Technology, U.S. Department of Commerce,
Technology Administration, PHYS A167, Gaithersburg, Maryland 20899
 

We observe transitions of laser-cooled Rb between vibrational levels in subwavelength-sized optical potential wells, using high-resolution spectroscopy of resonance fluorescence. We measure the spacing of the levels and the population distribution, and find the atoms to be localized to 1/15 of the optical wave-length. We find up to 60% of the population of trapped atoms in the vibrational ground state. The dependence of the spectrum on the parameters of the optical field provides detailed information about the dynamics of laser-cooled atoms.
 

Back | Full Text

Generation of a frequency comb with a double acousto-optic modulator ring

Poul Jessen and Martin Kristensen

Institute of Physics and Astronomy, University of Aarhus, DK-8000 Århus, C Denmark
 

We use an acousto-optic modulator ring setup to impose an asymmetric frequency comb on a dye laser. Applications include laser cooling of stored heavy ions.
 

Back | Full Text

Laser-rf double-resonance spectroscopy in a storage ring

M. Kristensen, J. S. Hangst, P. S. Jessen, J. S. Nielsen, O. Poulsen, and P. Shi

Institute of Physics and Astronomy, University of Aarhus, DK-8000 Århus, C Denmark
 

Laser-rf double-resonance spectroscopy of the hyperfine transition between F”=0 and F’= 1 in the metastable ‘Sl state of Li+ was performed in 100-keV beam in the storage ring ASTRID. High efficiency of optical pumping was demonstrated for complex pumping schemes. A broadband (dc —6 GHz) rf device was designed and used for rf spectroscopy in the storage ring. The possibility of obtaining coherent rf signals (Ramsey fringes) from successive interactions with the same field was investigated. Important limitations for the coherences due to magnetic-field inhomogeneities were observed. These led to randomization of the atomic polarization during only one turn in the storage ring and completely prevented observation of Ramsey fringes. This situation is different from the case of fundamental particles in a storage ring, where the polarization may be preserved for many round-trips. Limits were put on the demands to beam quality, beam positioning, and magnetic-field quality to overcome the problem. The effects of the rf device on the external degrees of freedom of the ion beam were investigated. Its small aperture substantially reduced the beam lifetime, and at very low rf frequencies the electric field in the rf device was able to excite external transverse resonances in the beam.
 

Back | Full Text