Title: The TUS detector of extreme energy cosmic rays on board the Lomonosov satellite,
Abstract: The origin and nature of extreme energy cosmic rays (EECRs), which have
energies above the 50 EeV, the Greisen-Zatsepin-Kuzmin (GZK) energy limit, is
one of the most interesting and complicated problems in modern cosmic-ray
physics. Existing ground-based detectors have helped to obtain remarkable
results in studying cosmic rays before and after the GZK limit, but have also
produced some contradictions in our understanding of cosmic ray mass
composition. Moreover, each of these detectors covers only a part of the
celestial sphere, which poses problems for studying the arrival directions of
EECRs and identifying their sources. As a new generation of EECR space
detectors, TUS (Tracking Ultraviolet Set-up), KLYPVE and JEM-EUSO, are intended
to study the most energetic cosmic-ray particles, providing larger, uniform
exposures of the entire celestial sphere. The TUS detector, launched on board
the Lomonosov satellite on April 28, 2016, from Vostochny Cosmodrome in Russia,
is the first of these. It employs a single-mirror optical system and a
photomultiplier tube matrix as a photo-detector and will test the fluorescent
method of measuring EECRs from space. Utilizing the Earth's atmosphere as a
huge calorimeter, it is expected to detect EECRs with energies above 100 EeV.
It will also be able to register slower atmospheric transient events:
atmospheric fluorescence in electrical discharges of various types including
precipitating electrons escaping the magnetosphere and from the radiation of
meteors passing through the atmosphere. We describe the design of the TUS
detector and present results of different ground-based tests and simulations.