Test Results of a Phi Monitoring System

The development and tests of a Phi monitoring system prototype designed for the CMS Muon Spectrometer alignment are described. The system, using a sweeping laser beam, defines a light reference plane to be used for the continuous monitoring of the Muon detectors. The performance of the system in the Laboratory was satisfactory. It showed good stability and linearity response behaviour. With the appropriate selection of components it can monitor large range position shifts ( up to 1-2 cm) with good accuracy at long distances ( ~ 60 mu accuracy at 10 m).