RHIC crystal collimation

A new application of bent crystals is to use them to channel halo particles of circulating stored beams into a downstream collimator. By deflecting the halo particles into a collimator with such a crystal, it may be possible to improve the collimation efficiency as compared to a standard two stage collimation system. Prior to 2003, a bent crystal was installed in one ring (i.e. yellow) of the relativistic heavy ion collider (RHIC). We give a report of our channeling studies in RHIC and describe our experience using the bent crystal as a collimator. The results are discussed and compared to simulations and theoretical predictions.