Storage of crystalline ion beams

Recently, the phase transition of a low-energy ²⁴Mg⁺ ion beam into the Coulomb-ordered ´crystalline´ state could be realized in the rf quadrupole storage ring PALLAS at the LMU Munich. Thereby, an increase of the phase space density of the beam, subjected to longitudinal laser cooling, by about six orders of magnitude was observed. In this paper, we focus on the systematic experimental investigation of the role of the focusing conditions and of bending shear in the storage ring on the attainment of crystalline beams of different crystal structure.