THE NOVEL OPTICAL NOTCH FILTER FOR STOCHASTIC COOLING AT THE ESR

In the frame of the development for the FAIR facility at GSI, notch filter cooling is essential for the stochastic cooling system of the CR (Collector Ring). A prototype notch filter based on optical components has been developed and assembled. The focus was to achieve sufficient notch depth and low periodicity error of the filter transfer function. The compact optical notch filter was integrated into the ESR stochastic cooling system. Longitudinal cooling of heavy ion beams was successfully demonstrated. The layout of the notch filter and the experimental results are presented.