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 5 · 10 19 eV, 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 photodetector 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 10 20 eV. 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.

Open Questions in Cosmic-Ray Research at Ultrahigh Energies

“…New physics of different types can affect all neutrino observables: the energy spectrum (see e.g., Baerwald et al, 2012;Blum et al, 2014;Ibe and Kaneta, 2014;Ioka and Murase, 2014;Ng and Beacom, 2014;Kopp et al, 2015;Bustamante et al, 2017), distribution of arrival directions (see e.g., Davis and Silk, 2015;Argüelles et al, 2017), and the flavor composition, i.e., the proportion of each neutrino flavor to the total in the incoming flux (see e.g., Argüelles et al, 2015;Bustamante et al, 2015;Shoemaker and Murase, 2016;Rasmussen et al, 2017).…”

First results from the TUS orbital detector in the extensive air shower mode

“…The central processor board gathers information from all modules, controls their operation, and implements the second-level trigger algorithm. More details on the design of TUS and its photodetector operation can be found in [21,22]. The TUS electronics can operate in four modes intended for detecting various fast optical phenomena in the atmosphere on different time scales.…”

Search and Study of Extensive Air Shower Events With the Tus Space Experiment

“…This procedure selects cases of sequential triggering of spatially contiguous active pixels that are also adjacent in time, allowing for the selection of events with a special spatial-temporal pattern. The design of the TUS detector and its performance is presented in more detail in [5].…”