Radiopure Scintillating Plastics for Rare-Event Physics Experiments

Rare-event physics experiments, such as searches for neutrinoless double-beta decay, dark matter interactions, and other beyond-Standard-Model processes, require ultra-low background environments to achieve their sensitivity goals. Radiopure materials with multiple functions, such as providing mechanical strength while enabling active background rejection, are increasingly important as they ensure that any added mass in a low background detector also contributes to suppressing backgrounds. Poly(ethylene-2,6-naphthalate) (PEN) has emerged as a promising candidate due to its intrinsic scintillation properties, chemical stability, and compatibility with cryogenic environments. Recent implementations of PEN in experiments such as LEGEND-200 have demonstrated its dual role as a structural material and as an active component for background identification. These results underscore the broader potential for PEN and similar plastics in future rare-event physics experiments. Ongoing research includes the development of modified PEN material and the application of additive manufacturing to produce complex, radiopure scintillating geometries tailored to experiment-specific needs. This presentation will review recent progress in the synthesis, radiopurity, and scintillation performance of these improved materials, highlight lessons learned from current experimental deployments, and explore applicability across a wide range of next-generation rare-event physics experiments .