Imaging of neutrino interactions using coded aperture masks

Abstract DUNE is a new-generation long-baseline neutrino experiment in the United States. The GRanular Argon for Interactions of Neutrinos (GRAIN) detector, a component of the SAND apparatus within the DUNE Near Detector complex, will play an important role in characterizing the neutrino beam and improving LAr interaction models. The GRAIN detector aims to perform imaging of neutrino interactions using scintillation light produced in argon, providing vertexing and tracking information on its own and, when combined with other detection methods, enhancing spatial resolution and improving event reconstruction in high-rate environments. This article describes an innovative cryogenic light readout system in which the sensor consists of a matrix of SiPMs, and the optics are implemented through coded aperture masks (grids of alternating opaque material and open holes). A prototype of this technology, along with its associated readout system, has been developed for testing, accompanied by a full Monte Carlo simulation and reconstruction chain to assess the expected performance. The reconstruction algorithm, based on the Maximum Likelihood Expectation-Maximization method, combines the views from approximately 60 cameras to produce a voxelized three-dimensional map of the energy deposited by charged particles.