Exploring the high-energy universe with a novel photodetector configuration

Water Cherenkov detectors (WCDs) are key in exploring high-energy astrophysical phenomena. They offer a lower-cost and accessible alternative to space-based instruments for detecting high-energy particles. This contribution introduces a novel photodetector configuration as a smaller and cost-effective alternative to the traditionally used large photomultiplier tubes (PMTs). We present the tests performed at the University of Leicester, employing a custom-built water Cherenkov detector — featuring a downward-facing 3-inch PMT coupled with wavelength-shifting (WLS) plates. In parallel, GEANT4 Monte Carlo simulations are being conducted to model the performance of this new configuration. The unit is designed to identify hadronic events for WCDs like those envisaged for the Southern Wide-field Gamma-ray Observatory (SWGO).