Horizon-T experiment and detection of Extensive air showers with unusual structure

Abstract

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.