Radiative Cooling of Ion Beams in Storage Rings by Broad-Band Lasers

A scheme for cooling nonfully stripped ions in storage rings is described in which photons in a counterpropagating laser beam are resonantly scattered by atomic electrons. The laser frequency is near one of the ion's transition frequencies, with a sufficiently broad bandwidth to cover the ions' full Doppler spectrum. Except for the resonance, this cooling is similar to radiative cooling in electron storage rings and works in all three directions. The scheme is distinct from the usual laser cooling which uses narrow-band lasers to resolve the line shape of individual ions. Explicit examples show that the scheme provides an efficient cooling of the beams, while producing intense $\gamma$ rays or x rays.