Water-Based Liquid Scintillator: Science Drivers and Technological Development

Abstract

Water-based liquid scintillator (WbLS) is a hybrid detection medium that blends the scalability and directional information of water Cherenkov detectors with the enhanced light yield and low-energy sensitivity of organic liquid scintillators. This review synthesizes the chemistry and formulation of WbLS, its optical and temporal response, photodetector technologies that enable WbLS detection, and recent advances in prototypes and deployments. A survey of science drivers spanning neutrino oscillation physics, solar and supernova neutrinos, and nuclear nonproliferation monitoring is presented, and a staged road map toward multikiloton WbLS facilities is outlined. Particular emphasis is placed on Cherenkov–scintillation separation via spectral and topological techniques and on metal-loading strategies for neutron tagging and rare-event signatures. The review concludes with open challenges in stability, purification, and system integration and highlights opportunities for synergy with slow scintillators and segmented readouts.