The Extensive Air Shower (EAS) data collected by the Horizon-10T detector system has numerous events exhibiting the unusual spatial and temporal structure. These are events typically with two to four pulses of tens of ns wide that are present at distances above 300 m from the EAS axis, with these pulses being delayed by hundreds of ns. Each of such pulse groups were registered simultaneously by several detectors separated by up to a km from each other. The detectors brief overview and the analysis of simulated EAS by the CORSIKA software package are given in this article. The analysis indicates that such events with unusual structure cannot be formed by showers with EM and hadronic components only. This indicates a possibility for a new process observation beyond the standard model description in the energy range above ~1018 eV.

Horizon-T is an innovative detector system constructed to study temporary structure of Extensive Air Showers (EAS) in the energy range above ~1016 eV coming from a wide range of zenith angles (up to 80°). The system, located at Tien Shan high-altitude Science Station at approximately 3340 meters above the sea level, consists of eight charged particle detection points separated by the distance up to one kilometer. The time resolution of charged particles passage of the detector system is a few ns. This level of resolution allows conducting research of atmospheric development of individual EAS. The total of ~8500 Extensive Air Showers (EAS) with the energy above 1016 eV has been detected during the ~4000 hours of Horizon-T detectors system operations since October 24, 2016 to April 21, 2017. A notable number of events has a spatial and temporary structure that showed the pulses with several maxima (modals or modes) from several detection points of the Horizon-T at the same time as described further in this work. These modes are separated in time from each other starting from tens to thousands of ns. Some are further classified as unusual event with common structure.

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In cosmic rays physics often a simple charged particle detector with fast response, best possible pulse time resolution and large linear range is required. For that purpose, we have developed a design that is based on the detection of Cherenkov radiation produced by charged particles in a thick optical glass used as a detection medium by a photomultiplier tube. In this work, the results of detector parameters simulation and experimental verification are presented. K: Cherenkov detectors; Detector design and construction technologies and materials; Simulation methods and programs 1Corresponding author.

"Horizon-T" is an innovative detector system located at Tien Shan high-altitude Science Station (TSHASS) at approximately 3340 meters above the sea level. It consists of eight detection points separated by the distance up to one kilometer that can measure time characteristics of the Extensive Air Showers (EAS) and record signal shapes with time resolution of ~10 ns. It was constructed to register EAS in the energy range above 10 16 eV coming from a wide range of zenith angles (0 o -85 o ). The system includes both the plastic scintillator particle detectors as well as the Vavilov -Cerenkov radiation detectors subsystem to observe the Cerenkov light from the EAS in the atmosphere directly. The time resolution and signal shape analysis capabilities of the detection points are used to study EAS development in the atmosphere.The development of the EAS is a process that can be studied both spatially and temporally. For the spatial part, a distributed network of detection points is required. For the time part, a signal shape must be recorded and analysed at each point with time resolution on the order of ~10 ns. In this paper, the current system description and performance level are described. Additionally, the latest data examples showing the unusual EAS examples above 10