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## Publications UHECR

The Network Architecture of the Data-processing System for the Photodetector of an Orbital Detector of Ultra-high Energy Cosmic Rays

An orbital detector of ultra-high energy cosmic rays has been developed by the Skobel’tsyn Institute of Nuclear Physics of the Moscow State University together with the international JEM-EUSO collaboration for mounting on board the International Space Station. Its multichannel photodetector is composed of an array of multianode photomultiplier tubes (MAPMTs) combined into modules with 36 MAPMTs in each and with approximately 105 pixels in total. Since the number of channels is great and the speed of measurements is high, high requirements are set for the system of detection, selection, and analysis of events. The designs of the modular photodetector composition and the network architecture of the data processing system that is capable of performing efficient selection of events with different space−time structures are presented. The network principle is implemented via three types of communications: high-speed links between adjacent photodetector modules, long-distance communications for recording information to the permanent memory, and synchronizing links for timing the operation of individual modules. This digital-processing system of the detector can be designed using the ZYNQ system-on-chip concept that includes a field programmable gate array and a processor system.

19.02.2018 Belov A.A., Klimov P.A., Sharakin S.A. Instruments and Experimental Techniques, 61(1):27–33, 2018.

Optical system for orbital detector of extreme-high-energy cosmic ray

An optical system of a Schmidt-type telescope for orbital detection is proposed. The system contains a spherical mirror and correction plate with one aspherical surface and has the following characteristics: field of view (FoV) is 40 deg, entrance pupil diameter is 2.5 m, diameter of spherical mirror is 4 m, and f -number is 0.74. The system with the described parameters has image spot size of 3.2-mm (RMS) diameter for the axial beam and 4 mm (RMS) on the edge of the FoV, which is less than the diagonal of the detectors square pixel of 3×3 mm2 3×3  mm2.

19.02.2018 Vladislav V. Druzhin; Daniil T. Puryaev; Sergey A. Sharakin J. of Astronomical Telescopes, Instruments, and Systems, 4(1), 014002 (2018).

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

TUS (Tracking Ultraviolet Set-up), the first orbital detector of extreme energy cosmic rays (EECRs), those with energies above 50 EeV, was launched into orbit on April 28, 2016, as a part of the Lomonosov satellite scientific payload. The main aim of the mission is to test a technique of registering fluorescent and Cherenkov radiation of extensive air showers generated by EECRs in the atmosphere with a space telescope. We present preliminary results of its operation in a mode dedicated to registering extensive air showers in the period from August 16, 2016, to November 4, 2016. No EECRs have been conclusively identified in the data yet, but the diversity of ultraviolet emission in the atmosphere was found to be unexpectedly rich. We discuss typical examples of data obtained with TUS and their possible origin. The data is important for obtaining more accurate estimates of the nocturnal ultraviolet glow of the atmosphere, necessary for successful development of more advanced orbital EECR detectors including those of the KLYPVE (K-EUSO) and JEM-EUSO missions.

29.12.2017 Khrenov B.A., Klimov P.A., Panasyuk M.I., et al. Journal of Cosmology and Astroparticle Physics

The TUS Detector of Extreme Energy Cosmic Rays on Board the Lomonosov Satellite

The origin and nature of extreme energy cosmic rays (EECRs), which have energies above the —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 ${}^{}$.

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.

29.12.2017 Klimov P.A., Panasyuk M.I., Khrenov B.A., et al. Space Science Reviews

Early Results from TUS, the First Orbital Detector of Extreme Energy Cosmic Rays

TUS is the world's first orbital detector of extreme energy cosmic rays (EECRs), which operates as a part of the scientific payload of the Lomonosov satellite since May 19, 2016. TUS employs the nocturnal atmosphere of the Earth to register ultraviolet (UV) fluorescence and Cherenkov radiation from extensive air showers generated by EECRs as well as UV radiation from lightning strikes and transient luminous events, micro-meteors and space debris. The first months of its operation in orbit have demonstrated an unexpectedly rich variety of UV radiation in the atmosphere. We briefly review the design of TUS and present a few examples of events recorded in a mode dedicated to registering EECRs.

04.04.2017 Mikhail Zotov, for the Lomonosov-UHECR/TLE Collaboration Arxiv.org (Submitted on 28 Mar 2017 (v1), last revised 2 Apr 2017 (this version, v2))

First results of the Lomonosov TUS and GRB experiments

On April 28, 2016, the Lomonosov satellite, equipped with a number of scientific instruments, was launched into orbit. Here we present briefly some of the results obtained with the first orbital telescope of extreme energy cosmic rays TUS and by a group of detectors aimed at multi-messenger observations of gamma-ray bursts.

arXiv:1703.03738

04.04.2017 S.V. Biktemerova, A.V. Bogomolov, V.V. Bogomolov, A.A. Botvinko, A.J. Castro-Tirado, E.S. Gorbovskoy, N.P. Chirskaya, V.E. Eremeev, G.K. Garipov, V.M. Grebenyuk, A.A. Grinyuk, A.F. Iyudin, S. Jeong, H.M. Jeong, N.L. Jioeva, P.S. Kazarjan, N.N. Kalmykov, M.A. Kaznacheeva, B.A. Khrenov, M.B. Kim, P.A. Klimov, E.A. Kuznetsova, M.V. Lavrova, J. Lee, V.M. Lipunov, O. Martinez, I.N. Mjagkova, M.I. Panasyuk, I.H. Park, V.L. Petrov, E. Ponce, A.E. Puchkov, H. Salazar, O.A. Saprykin, A.N. Senkovsky, S.A. Sharakin, A.V. Shirokov, S.I. Svertilov, A.V. Tkachenko, L.G. Tkachev, I.V. Yashin, M.Yu. Zotov Arxiv.org (Submitted on 10 Mar 2017 (v1), last revised 26 Mar 2017 (this version, v2))

Preliminary results from the TUS ultra-high energy cosmic ray orbital telescope: Registration of low-energy particles passing through the photodetector

The TUS telescope, part of the scientific equipment on board the Lomonosov satellite, is the world’s first orbital detector of ultra-high energy cosmic rays. Preliminary results from analyzing unexpected powerful signals that have been detected from the first days of the telescope’s operation are presented. These signals appear simultaneously in time intervals of around 1 μs in groups of adjacent pixels of the photodetector and form linear track-like sequences. The results from computer simulations using the GEANT4 software and the observed strong latitudinal dependence of the distribution of the events favor the hypothesis that the observed signals result from protons with energies of several hundred MeV to several GeV passing through the photodetector of the TUS telescope.

04.04.2017 P. A. Klimov, M. Yu Zotov, N. P. Chirskaya, B. A. Khrenov, G. K. Garipov, M. I. Panasyuk, S. A. Sharakin, A. V. Shirokov, I. V. Yashin, A. A. Grinyuk, A. V. Tkachenko, L. G. Tkachev

The orbital TUS detector simulation

The TUS space experiment is aimed at studying energy and arrival distribution of UHECR at E>7 × 1019 eV by using the data of EAS fluorescent radiation in atmosphere. The TUS mission was launched at the end of April 2016 on board the dedicated “Lomonosov” satellite. The TUSSIM software package has been developed to simulate performance of the TUS detector for the Fresnel mirror optical parameters, the light concentrator of the photo detector, the front end and trigger electronics. Trigger efficiency crucially depends on the background level which varies in a wide range: from  0.2 × 106 to  15 × 106 ph/( m2 μs sr) at moonless and full moon nights respectively. The TUSSIM algorithms are described and the expected TUS statistics is presented for 5 years of data collection from the 500 km solar-synchronized orbit with allowance for the variability of the background light intensity during the space flight.

04.04.2017 A. Grinyuk, V. Grebenyuk, B. Khrenov, P. Klimov, M. Lavrova, M. Panasyuk, S. Sharakin, A. Shirokov, A. Tkachenko, L. Tkachev, I. Yashin Astroparticle Physics, Volume 90, April 2017, Pages 93-97

Detection prospects of the Telescope Array hotspot by space observatories

In the present-day cosmic ray data, the strongest indication of anisotropy of the ultrahigh energy cosmic rays is the 20-degree hotspot observed by the Telescope Array with the statistical significance of 3.4σ. In this work, we study the possibility of detecting such a spot by space-based all-sky observatories. We show that if the detected luminosity of the hotspot is attributed to a physical effect and not a statistical fluctuation, the KLYPVE and JEM-EUSO experiments would need to collect 300events with E>57EeV in order to detect the hotspot at the 5σ confidence level with the 68% probability. We also study the dependence of the detection prospects on the hotspot luminosity.

26.07.2016 D. Semikoz, P. Tinyakov, and M. Zotov Phys. Rev. D 93, 103005 – Published 23 May 2016

Space experiment TUS on board the Lomonosov satellite as pathfinder of JEM-EUSO

Space-based detectors for the study of extreme energy cosmic rays (EECR) are being prepared as a promising new method for detecting highest energy cosmic rays. A pioneering space device – the “tracking ultraviolet set-up” (TUS) – is in the last stage of its construction and testing. The TUS detector will collect preliminary data on EECR in the conditions of a space environment, which will be extremely useful for planning the major JEM-EUSO detector operation.

26.11.2015 The JEM-EUSO Collaboration Experimental Astronomy, November 2015, Volume 40, Issue 1, pp 315-326

Ultra high energy cosmic ray detector KLYPVE on board the Russian Segment of the ISS

Modiﬁed KLYPVE is a novel ﬂuorescence detector of ultra high energy cosmic rays (UHECRs, energies ≥50EeV) to be installed on the Russian Segment of the International Space Station. The main goal of the experiment is to register arrival directions and energies of UHECRs but it will be able to register other transient events in the atmosphere as well. The main component of KLYPVE is a segmented two component optical system with a large entrance pupil and a wide ﬁeld of view, which provides annual exposure approximately twice that of the Pierre Auger Observatory. The project is actively developed by a working group of the JEM-EUSO Collaboration led by Skobeltsyn Institute of Nuclear Physics at Moscow State University (Russia). The current status ofKLYPVE with a focus on its scientiﬁc tasks, technical parameters and instruments is presented.

11.10.2015 M. I. Panasyuk, P. Picozza, M. Casolino, T. Ebisuzaki, P. Gorodetzky, B. A. Khrenov, P. A. Klimov, S. A. Sharakin and M. Yu. Zotov Proc. ICRC-2015 PoS(ICRC2015)669

The KLYPVE ultrahigh energy cosmic ray detector on board the ISS.

The current status of the KLYPVE orbital detector of ultrahigh energy cosmic rays, which is scheduled to be deployed on board the Russian module of the International Space Station, is discussed. The main focus is on describing possible optical systems for the instrument.

11.10.2015 G.K. Garipov, M.Yu Zotov, P.A. Klimov, M.I. Panasyuk, O.A. Saprykin, L.G. Tkachev, S.A. Sharakin, B.A. Khrenov, and I.V. Yashin Bulletin of the Russian Academy of Science, Physics, 79(3):326–328, 2015.

The current status of orbital experiments for UHECR studies

Two types of orbital detectors of extreme energy cosmic rays are being developed nowadays: (i) TUS and KLYPVE with reflecting optical systems (mirrors) and (ii) JEM-EUSO with high- transmittance Fresnel lenses. They will cover much larger areas than existing ground-based arrays and almost uniformly monitor the celestial sphere. The TUS detector is the pioneering mission developed in SINP MSU in cooperation with several Russian and foreign institutions. It has relatively small field of view (±4.5°), which corresponds to a ground area of 6.4•103 km2 . The telescope consists of a Fresnel-type mirror-concentrator ( 2 m2 ) and a photo receiver (a matrix of 16 x 16 photomultiplier tubes). It is to be deployed on the Lomonosov satellite, and is currently at the final stage of preflight tests. Recently, SINP MSU began the KLYPVE project to be installed on board of the Russian segment of the ISS. The optical system of this detector contains a larger primary mirror (10 m 2 ), which allows decreasing the energy threshold. The total effective field of view will be at least ±14° to exceed the annual exposure of the existing ground-based experiments. Several configurations of the detector are being currently considered. Finally, JEM-EUSO is a wide field of view (±30°) detector. The optics is composed of two curved double-sided Fresnel lenses with 2.65 m external diameter, a precision diffractive middle lens and a pupil. The ultraviolet photons are focused onto the focal surface, which consists of nearly 5000 multi-anode photomultipliers. It is developed by a large international collaboration. All three orbital detectors have multi-purpose character due to continuous monitoring of various atmospheric phenomena. The present status of development of the TUS and KLYPVE missions is reported, and a brief comparison of the projects with JEM-EUSO is given. [http://iopscience.iop.org/article]

11.10.2015 M.I. Panasyuk, M. Casolino, G.K. Garipov, T. Ebisuzaki, P. Gorodetzky, B.A. Khrenov, P.A. Klimov, V.S. Morozenko, N. Sakaki, O.A. Saprykin, S.A. Sharakin, Y. Takizawa, L.G. Tkachev, I.V. Yashin, and M.Yu Zotov Journal of Physics, 632(1):012097, 2015.

19.02.2018