Design and characterization of large-size monolithic layers of 3D-segmented plastic scintillator

Three-dimensional fine-grained plastic scintillator detectors are extensively used in high-energy physics experiments where particle tracking, identification, calorimetry and sub-nanosecond timing information are required. Moreover, the low cost of plastic scintillator makes, in principle, the scalability to multi-tonne detectors possible. In order to circumvent the difficulties related to the long production time and the challenging assembly of millions of tiny independent scintillating voxels, a new technology consisting of gluing a few thousand $9\times 9\times 9$ mm${}^3$ plastic scintillator cubes in a single large monolithic layer with machining precision, while ensuring an efficient optical separation, was developed and demonstrated. In this work we demonstrate that such technology can be reliably extended to a monolithic layer of $48\times 48$ optically-isolated scintillating cubes, the size required for future ton-scale detectors, fulfilling the requirements of future neutrino detectors and sampling calorimeters.