  The Relativistic Heavy Ion Collider (RHIC) will experience increasing
longitudinal and transverse heavy ion emittances, mostly due to intra-beam
scattering (IBS). The experiments in RHIC are expected to not only have reduced
luminosities due to IBS but also an unwanted beam halo. Primary betatron
collimators will be used to remove the large amplitude particles. The
efficiency of the primary collimator in RHIC depends very much on the alignment
of the jaws which needs to be within few micro-radians for the best conditions.
As proposed by V. Biryukov bent crystals could be used to improve the
efficiency of an existing collimation system by installing them upstream of the
collimator jaws. Bent crystals have been successfully used in SPS, Protvino and
Fermilab for extraction of the beam particles channeled through them. This
study examines possible improvements of the primary collimator system for heavy
ions at RHIC by use of bent crystals. Bent crystals will reduce the collimator
jaws alignment requirement and will increase collimator efficiency thereby
reducing detector background.
