Development of a Water Cerenkov Detector Prototype with Wavelength Shifters and Silicon Photomultiplier Readout.

Indirect high energy cosmic and gamma ray experiments require cost effective detectors and a large coverage area. Water Cherenkov detectors with large photomultiplier tubes have been commonly used for these experiments. While the photomultiplier tubes have good dynamic range and could be manufactured to larger sizes, their main drawbacks are high voltage to operate and sensitivity to magnetic fields. Silicon photomultipliers are the solid state counterparts which are insensitive to magnetic fields and operate at lower voltage, but have smaller area. At a time when solid state silicon photomultiplier vendors are growing and photomultiplier tubes declining, it is of paramount importance to develop alternative cost-effective readout schemes for future experiments. We developed a prototype water Cherenkov detector with wavelength shifting fibers and silicon photomultiplier readout. We report on the performance of this prototype for cosmic ray muons. We used Geant4 simulations to extrapolate performance at larger sizes.