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Raymond Fliller III
RHIC Crystal Collimation System
The Crystal Collimation System
of the Relativistic Heavy Ion
Collider
Employment: Research
Associate – Fermilab A0
Photoinjector Project
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Crystal channeling occurs when ions entering a crystal
with small angles relative to the crystal planes follow
the planes, even if the crystal is bent. Our 5mm long
crystal deflects particles by 440 mrad. A 5 mm dipole
magnet would need to be 75 T for the same bend angle
at RHIC energies!
Bent crystals were investigated as the first stage of a
two stage collimation system in RHIC. The bent
crystal deflects halo particles into a downstream
absorber. This should remove the beam halo more
efficiently than a convention two stage collimation
system.
Optical errors reduced the channeling efficiency. This
increased backgrounds in the RHIC experiments during
crystal collimation instead of reducing them.
The crystal collimator was removed. The RHIC
collimation system was upgraded to a conventional two
stage system.
Reduced scattering from crystal
shows channeling
STAR Background
during Crystal
Collimation