Development of a 3D highly granular scintillator neutrino detector for the T2K experiment

An essential component of the T2K near detector upgrade is a highly segmented scintillator detector, acting as a fully active target for the neutrino interactions. The baseline concept for it is a novel device, called SuperFGD (arXiv:1707.01785), with dimensions of 200x180x60 cm3. It consists of about 2x106 small scintillator cubes each of 1 cm3. The signal readout from each cube is provided by 3 WLS fibers. We have demonstrated that this detector, providing three 2D projections, has excellent tracking performance, including a 4 π angular acceptance. Interest in this detector has been expressed by groups of the DUNE and ESS-nu collaboration. A small prototype of this detector composed of 125 cubes was tested in a beam of charged particles at CERN in 2017. The detector response of this prototype, will be presented. The progress in the R&D of this detector, future plans and results of simulations will be also reported.