First demonstration of “white-light” laser cooling of a stored ion beam (original) (raw)

“White-light” Laser Cooling of a Fast Stored Ion Beam

Physical Review Letters, 1998

We report the experimental demonstration of "white-light" cooling of a high-velocity 7 Li 1 ion beam stored at 6.4% of the speed of light in a storage ring. In a direct comparison with single-mode laser cooling, we show that white-light cooling is much more efficient to counteract strong intrabeam heating and leads to lower longitudinal beam temperatures at higher ion densities, i.e., much higher densities in longitudinal phase space. [S0031-9007(98)05508-2] PACS numbers: 29.20.Dh, 32.80.Pj, 42.50.Vk In ion storage rings, established in the past decade as powerful instruments for precision experiments in atomic and nuclear physics [1], cooling techniques [2] play a key role in the production of beams of high brilliance and quality. In accelerator physics, very cold and highly dense ion beams are of great interest for exploring the beam dynamics at highest phase-space densities and for approaching a regime in which the beam behaves as a strongly coupled one-component plasma. Laser cooling [3-8] provides an extremely fast and efficient cooling and thus offers unique possibilities to enter this regime and to attain beams with liquidlike or solidlike Coulomb ordering .

Laser cooling of a fast ion beam

Journal of the Optical Society of America B, 1985

A theoretical analysis of light-pressure cooling of a fast ion beam is given. The light-induced velocity changes are compensated by accelerating the ions by an external electric field. By analyzing the Fokker-Planck equation, cooling times and the ultimate temperature of the ions are given. It is argued that the transverse heating and the diffusion to velocities that are not cooled should pose no serious problems in realistic experimental cases. The particular physical conditions in a heavy-ion storage ring are finally discussed.

Two-dimensional Cooling of Ion Beams in Storage Rings by Narrow Broad-Band Laser Beams

A new scheme for the two-dimensional cooling of ion beams in storage rings is suggested in which ions interact with a counterpropagating broad-band laser beam. The interaction region in the direction of the ion movement is much less then the wavelength of the ion betatron oscillations. The laser beam in the orbit plane has sharp flat edge directed to the ion beam and the width of the laser beam of the order of the ion beam width. Laser beam radial position is being displaced with some velocity at first from inside and then from outside to the ion beam and decreases both betatron and synchrotron oscillations.

From laser cooling of non-relativistic to relativistic ion beams

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2004

Laser cooling of stored 24 Mg þ ion beams recently led to the long anticipated experimental realization of Coulombordered 'crystalline' ion beams in the low-energy RF-quadrupole storage ring PAul Laser CooLing Acceleration System (Munich). Moreover, systematic studies revealed severe constraints on the cooling scheme and the storage ring lattice for the attainment and maintenance of the crystalline state of the beam, which will be summarized. With the envisaged advent of high-energy heavy ion storage rings like SIS 300 at GSI (Darmstadt), which offer favourable lattice conditions for space-charge-dominated beams, we here discuss the general scaling of laser cooling of highly relativistic beams of highly charged ions and present a novel idea for direct three-dimensional beam cooling by forcing the ions onto a helical path.

Sharp edge broad-band lasers for "white-light" cooling in storage rings

Hyperfine Interactions, 1997

We have developed broad-band laser sources which show a sharp edge in their spectra and are particularly suitable for ``white-laser'' cooling of ions in storage rings. They allow for a very large velocity capture range by maintaining the same cooling rate allowed by the single mode lasers. A large fraction of the circulating ions are expected to be cooled both in coasting and bunched beams. The device, which does not use an active medium, can easily operate at any frequency from UV to IR spectral region.

Laser cooling of stored beams in ASTRID

Conference Record of the 1991 IEEE Particle Accelerator Conference, 1991

We report the results of laser cooling experiments on 100 keV Li+ beams in the storage ring ASTRlD. The metastable fraction of the lithium beam has been laser cooled to a momentum spread dp/p-10-6, corresponding to a rest frame temperature T,, = 1 mK. Laser diagnostic methods have been employed to study the dynamics of intrabeam relaxation. A theoretical model of laser cooling has been used to interpret the experimental results. Wealso discuss Molecular Dynamics simulations of intrabeam interactions and the connection with crystalline beams.

A new concept for cooling low-energy ion beams

Journal of Physics B: Atomic, Molecular and Optical Physics, 2003

We are investigating a new concept of a buffer gas filled ion cooler built from single radio frequency (RF) ring electrodes. In such a ring electrode structure, the RF potential generates an average repelling short-range force perpendicular to the electrode surfaces. Due to the composition of single rings, the shape of the cooling channel can easily and smoothly be varied, and hence also the direction of the RF forces. As a result, the angular acceptance can be increased by a factor of two in comparison to the maximum acceptance for the present RF quadrupole coolers.

Combined Laser and Electron Cooling of Bunched C3+ Ion Beams at the Storage Ring ESR

2006

We report on first laser cooling studies of bunched beams of triply charged carbon ions stored at an energy of 1.46 GeV at the ESR (GSI). Despite for the high beam energy and charge state laser cooling provided a reduction of the momentum spread of one order of magnitude in spacecharge dominated bunches as compared to electron cooling. For ion currents exceeding 10 µA intrabeam-scattering losses could not be compensated by the narrow band laser system presently in use. Yet, no unexpected problems occurred encouraging the envisaged extension of the laser cooling to highly relativistic beams. At ESR, especially the combination with modest electron cooling provided three-dimensionally cold beams in the plasma parameter range of unity, where ordering effects can be expected and a still unexplained signal reduction of the Schottky signal is observed.