An optical calibration manipulator system

The K2K experiment at KEK is searching for neutrino oscillations by measuring the neutrino beam flux at both a 1 kilotonne water Cherenkov detector (front detector) close to the neutrino source, and at the Super Kamiokande detector 250 km away. Part of the optical calibration of the front detector is accomplished by transmitting laser light via a fiber optic cable to a light-diffusing ball immersed in the water. A manipulator system has been built to position the ball at various locations within the water volume. A description of the mechanics and the control system is presented.