Colliding crystalline beams

Crystalline beams are an ordered state of an ensemble of ions, circulating in a storage ring, with very small velocity fluctuations. They can be obtained from ordinary warm ion beams with the application of powerful cooling techniques (stochastic, electron, laser, ...). Depending on the focusing properties and dimensions of the storage ring, and on the ion beam density, several ground states are possible. All of them can be visualized as a bundle of n_s symmetrically distributed, parallel strings. The longitudinal ion separation λ is the same for all strings. The minimum temperature that can be achieved depends on the background noise of the cooling technique used. It is required for stability that the vibration amplitude of the ions is only a fraction of the separation λ