**January 25 2013**

**New article: Phys. Rev. A 87, 013425 (2013).**

Stability and dynamics of ion rings in linear multipole traps

Florian Cartarius, Cecilia Cormick, Giovanna Morigi

Phys. Rev. A 87, 013425 (2013).

Trapped singly charged ions can crystallize as a result of laser cooling. The emerging structure depends on the number of particles and on the geometry of the trapping potential. In linear multipole radio frequency traps, the geometry of the radial potential can lead to the formation of single-ring structures. We analyze the conditions and stability of single rings as a function of the number of poles. The rings form tubes for a large number of ions and sufficiently small trap aspect ratios. In these structures the arrangement of the ions corresponds to a triangular lattice folded onto a cylinder. The stability of the tubular structures is numerically studied for different lattice constants and their normal-mode spectrum is determined.