Optimized lattice for the Collector Ring (CR)

The Collector Ring (CR) is designed for fast stochastic cooling of rare isotope beams (RIB) and, after changing the magnet polarity, of antiproton (pbar) beams. With the chosen layout of the CR lattice it is possible to find nearly optimal ring optics for both kinds of beams. This is necessary because of different ion velocity and different initial beam parameters. The RIB are injected at β∼0.83 with transverse emittances εperp of 200 mm mrad and a full momentum width (δp/p)FW of 3.5%, whereas the parameters for pbar beams are β∼0.95, εperp=240 mm mrad, and (δp/p)FW=6%. The CR has to be operated also in the so-called isochronous mode as TOF mass spectrometer for short-lived secondary nuclei. The ring consists of two arcs and two long straight sections. Presently two solutions for the CR lattice are under consideration: a 'symmetric ring' with identical lattice functions in the arcs and the 'split ring' with different lattice functions in the arcs. Results of particle tracking simulations for both types of lattices, taking into account all relevant higher order field effects, will be presented and discussed in our contribution