Search for Extreme Energy Cosmic Rays with the TUS orbital telescope and comparison with ESAF

Abstract

The Tracking Ultraviolet Setup (TUS) detector was launched on April 28, 2016 as a part of the scientific payload of the Lomonosov satellite. TUS is a pathfinder mission for future space-based observation of Extreme-Energy Cosmic Rays (EECRs, E > 5x1019 eV) with experiments such as K-EUSO. TUS data offer the opportunity to develop strategies in the analysis and reconstruction of the events which will be essential for future space-based missions. During its operation, TUS has detected about 80 thousand events which have been subject to an offline analysis to select among them those that satisfy basic temporal and spatial criteria of EECRs. A few events passed this first screening. In order to perform a deeper analysis of such candidates, a dedicated version of ESAF (EUSO Simulation and Analysis Framework) code as well as a detailed modelling of TUS optics and detector are being developed.

An EAS-like event registered with the TUS orbitaldetector

“…A thorough application of the procedure to the ten hit channels, which will be explained in details elsewhere, allowed us to estimate their new sensitivities. Together with extensive simulations of the detector response to EASs generated by primary particles in the energy range 100-1100 EeV performed with ESAF [12,13], this took us to the lower limit of the energy of an UHECR ≈ 1000 ± 200 EeV. Figure 4 illustrates an expected response of TUS to an EAS generated by a 1 ZeV proton arriving at the zenith angle θ ≈ 50 • .…”

“…EAS-like event registered with TUS M. Bertaina 0 20 (13,4) 0 20 (13,3) 0 10 (12,4) 0 20 (12,3) into account a limited exposure of the TUS mission (∼ 1200-1400 km 2 sr yr as the first extimation) and the fact that the flux of ZeV CRs is expected to be 2-4 orders of magnitude lower than that around 100 EeV, chances of TUS registering such an energetic cosmic particle are very low.…”

Application of Neural Networks to Classification of Data of the TUS Orbital Telescope

“…Miscellaneous examples of events of all types can be found in [12][13][14][15][16][17]. Please note that the four classes of events were not disjoint: in some cases an event of one type was registered simultaneously with an event of another type within one data record.…”

“…The data set obtained with TUS has demonstrated that an unexpected variety of different processes are taking place in the nocturnal atmosphere of the Earth in the ultraviolet (UV) range. Considerable efforts have been put in the analysis of the TUS data, see, e.g., [13][14][15][16][17]. Until recently, all of them were based on conventional approaches.…”

Kinematics reconstruction of the EAS-like events registered by the TUS detector

“…The detector operated till late 2017 and registered almost 80,000 events in the EAS mode. Several preliminary EAS candidates have been selected in the TUS data earlier [4,5]. The Lomonosov-UHECR/TLE Collaboration continues the TUS data analysis.…”