Organic glass scintillator formulations and mold development towards scalable and cast-in-place pixelated fabrications

Abstract

Herein we describe the development of organic glass scintillator (OGS) additives to enable the rapid and simple fabrication of form factors necessitated by pixelated neutron detection systems. These systems, developed for national security purposes, utilize arrays of many (O(100–1000))​ bar-shaped scintillators which are optically isolated and coupled to photodetectors. We describe two overall methods to address the construction of pixelated scintillator arrays at scale: individual bars cast directly in single bar molds, reducing the need to cut the bars to size, and casting directly into pixelated molds, eliminating both the need to cut the bars to size and to fabricate the array from individual bars. The mechanical blending of pre-polymerized plastic pellets of polystyrene and polycarbonate in OGS can be formulated up to 5% by weight into OGS to rigidify high aspect-ratio bars capable of withstanding the additional stress of being cast simultaneously side by side in a single pour with a variety of new mold materials. In addition, the inclusion of 15%–20% of “2-(p-tolyl)-1,3,2-dioxaborinane” (TDB) can enable direct, cast-in-place of OGS bars into aluminum or acetal sheet molds of arrays. We also describe the developments into the new mold materials and assembly to support the casting into these form factors. As a proof of concept, we cast a single pixel directly into a mold lined with 3M’s enhanced specular reflector (ESR) and characterize its performance for neutron detection applications.