Suppressing intrinsic spin harmonics at the cooler synchrotron COSY

Accelerating a polarized beam in a synchrotron requires the highest possible superperiodicity of the lattice in order to minimize the number of depolarizing intrinsic resonances. However, at the cooler synchrotron COSY the standard lattice to accelerate the beam to maximum momentum has a reduced superperiodicity since the harmful transition energy is shifted upwards during acceleration. This procedure allows internal experiments to take data in the whole acceleration ramp. Unfortunately the reduced superperiodicity excites additional intrinsic resonances. To solve this contrary situation a modified beam optics was found which significantly lowers the strength of these intrinsic resonances. Measurements confirming this theoretical concept are presented.