A NANOSECOND UV LIGHT SOURCE FOR MONITORING AND CALIBRATING WATER CERENKOV COUNTERS

Abstract

The characteristics of a water Cerenkov monitoring and calibrating system are described. A nitrogen laser provides nanosecond pulses of ultraviolet light. The time of firing and the pulse height of the light pulses are under computer control. The laser light is guided to the detectors by an optical fiber. At the end of the fiber the light pulse may be isotropically dispersed to light thousands of PMTs viewing the same water volume. The time resolution of PMTs as well as pulse height response and resolution (from the single photoelectron level to phototube saturation) are measured using a single fast photomultiplier tube and a 128 PMT array in air. This system will also be of use in calibrating liquid scintillator detectors.