Synthesis and Applications of Low Background Modified Polyethylene Naphthalate (PEN-G)

Identification of background radiation is of utmost importance for enabling rare event experiments to attain the required sensitivities for probing new physics. Poly(ethylene-2,6-naphthalate) (PEN) has emerged as a highly promising material for such experiments due to its intrinsic scintillating properties and its adaptability as a structural material at both room and cryogenic temperatures. Notably, PEN has been successfully implemented in the LEGEND-200 experiment involving the target isotope $^{76}$Ge for investigating neutrinoless double beta decay. In LEGEND-200, PEN serves as both an active material and a structural component within the detector assembly. Looking towards the next-generation experiment, LEGEND-1000 will further reduce background radiation by an order of magnitude. To achieve this goal, we are looking to expand more potential applications of PEN-G. To this end, we have successfully synthesized PEN in kilogram batches utilizing unique reagents. The radiopurity of the synthesized PEN has been measured, and we are exploring strategies to improve these values. In this presentation, we will outline the methods employed and present the corresponding results.