Optical properties of low background PEN structural components for the LEGEND-200 experiment

Abstract

A: Polyethylene Naphthalate (PEN) plastic scintillator has been identified as potential selfvetoing structural material in low-background physics experiments. Scintillating components have been produced radio-pure from PEN using injection compression molding technology. These lowbackground PEN components will be used as active holders to mount the Germanium detectors in the L -200 neutrinoless double beta decay experiment. In this paper we present the measurement of the optical properties of these PEN components. Thus, the emission spectrum, time constant, attenuation and bulk absorption length as well as light output and light yield are reported. In addition, the surface of these PEN components has been characterized and an estimation of the surface roughness is presented. Moreover, the light output of the final L -200 detector holders has been measured and is reported. These measurements were used to estimate the self-vetoing efficiency of these holders.