Design and characterization of small detection modules based on scintillators and WLS bars with SiPM readout for a cosmic ray mini-array

This paper describes the design and characterization tests of detection modules for a low-cost, easily reconfigurable mini-array for cosmic rays. The basic layout of each individual module is based on a 400 cm² scintillator tile, optically coupled to a Wavelength Shifter (WLS) bar and a Silicon Photomultiplier (SiPM) for light collection and readout. Low cost solutions, based on the Arduino MEGA board, have been adopted for electronics, triggering and data acquisition, in view of the operation of this facility. The first detection modules, equipped with 4×4 mm² SiPMs were fully built and characterized. Additional tests were also carried out with photosensors having different sensitive area and technology.