AMPLITUDE DEPENDENT TUNE SPREAD IN THE CR OPERATED AS AN ANTIPROTON COLLECTOR

In frame of the FAIR project [1] the Collector Ring is planned to be built for efficient cooling of antiprotons and rare isotopes beams. In order to accept hot antiproton beams coming from a separator [2] large aperture magnets are required. This paper examines the effects, which may influence on the beam dynamics because of large both an amplitude betatron oscillation (240 mm mrad) and large momentum spread (6%). Using analytic expressions the amplitude-dependent tune shifts driven by sextupole magnets, fringe field of quadrupole magnets and kinematic effects have been calculated. The obtained results are compared with numerical simulations. Tracking studies for the CR operated as an antiproton collector have been performed considering the real distribution of the magnetic field of the wide aperture quadrupole. We report on quantitative studies of the effects on the tune spread and its influence on the beam losses.