An in-vacuum Cherenkov beam monitor for UA9 at LHC

On behalf of the UA9 Cherenkov detector teamThe UA9 experiment is testing bent crystals to assist halo collimation in LHC using the crystal channeling effect. Beam monitors are proposed to be placed in vacuum to detect the channeled beam and to measure the fluence of the channeled particles. To intercept the channeled hadrons a silica radiator is placed in the beam pipe vacuum. Cherenkov light is produced and guided out of the pipe using radiation hard silica fibers. Light is finally detected with a Micro-Channel Plate photomultiplier. Simulation of the detector performances are presented and technical solutions for light transmission and detection in presence of the LHC high radiation environment and of the LHC stringent safety requirements are discussed