The Gamma-Flash real-time data pipeline for ground observation of terrestrial gamma-ray flashes

Gamma-Flash is an Italian project funded by the Italian Space Agency (ASI) and led by the National Institute for Astrophysics (INAF), devoted to the observation and study of high-energy phenomena, such as terrestrial gamma-ray flashes and gamma-ray glows produced in Earth's atmosphere during thunderstorms. The project represents the ground-based supplement to the work of the ASI AGILE satellite in this particular field. This contribution presents the architecture of the Gamma-Flash data pipeline placed at the Osservatorio Climatico "O. Vittori" on the top of Mt. Cimone (2165 m a.s.l., Northern-Central Italy). It consists of RedPitaya ARM-FPGA boards designed for acquiring events at different energies from scintillator crystals coupled to photomultiplier tubes, and a main computer that executes a real-time software pipeline. The software performs several data processing steps, data acquisition, data reduction level, algorithms for waveform selection, and finally it produces the cumulative energy spectrum of the gamma radiation collected by the photomultipliers. Data is stored in different layers, each with a different purpose, and it is available to the scientific community as HDF5 files. The pipeline has a modular architecture to provide good maintenance and flexibility, allowing for easy extensions in the future. A specific subset of data is stored in a database connected to a real-time graphical dashboard for quick-look analysis, showing the acquisition products and the environmental telemetry data.