Towards the second generation of the Fluorescence detector Array of Single-pixel Telescopes

The Fluorescence Detector Array of Single-pixel Telescopes (FAST) project proposes a simplified Schmidt telescope designed for the detection of ultra-high-energy cosmic rays. It maintains its optical excellence while featuring cost-effective components. The FAST prototype utilizes a segmented 1.6 m diameter mirror and four 200 mm photomultipliers at its focal plane. Currently, the first generation operates at the Telescope Array experiment and the Pierre Auger Observatory. Based on the experience from the first-generation prototype, the second generation is under development. Understanding the temperature and magnetic field dependence of the photomultipliers is essential for accurate event reconstruction. Therefore, thorough testing of individual detector components provides insight into the behavior of the FAST prototype. We introduce the second-generation FAST telescope, compare it to the first prototype, and present the results of photomultipliers characterization in the laboratory.