CRYSTAL COLLIMATION AT RHIC

For the year 2001 run, a bent crystal was installed in the yellow ring of the Relativistic Heavy Ion Collider (RHIC). The crystal forms the first stage of a two stage collimation system. By aligning the crystal to the beam, halo particles are channeled through the crystal and deflected into a copper scraper. The purpose is to reduce beam halo with greater efficiency than with a scraper alone. In this paper they present the first results from the use of the crystal collimator. They compare the crystal performance under various conditions, such as different particle species, and beta functions