First Results of Studying EAS Cores Using a High-Mountain Ionization Calorimeter

Abstract

In high-altitude experiments to study the central cores of EAS at E0 ≳ 1016 eV (√s ≳ 5 TeV) using X-ray emulsion chambers and ionization calorimeters, phenomena such as the coplanarity of the arrival of the most energetic particles in super families of γ-rays and hadrons and a so-called Tien Shan effect (too slow absorption of cascades initiated by high-energy hadrons in the calorimeter) were observed. These effects could not be reproduced within the framework of theoretical models of the 80s and 90s. The coplanarity is explained via a process of coplanar generation of the most energetic secondary particles in interactions of super high-energy hadrons with nuclei of air atoms. Perhaps the Tien Shan effect could be explained using a high cross section for the generation of fragmentation-region charmed hadrons. To study these phenomena, a new set of detectors has been developed, including the world’s highest high-mountain ionization calorimeter, “Hadron-55”. This paper presents the initial experimental results.

Keywords

• cosmic rays
• ionization-neutron calorimeter
• scintillation detector
• ionization chambers
• hadron cascade
• extensive air shower (EAS)