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Simulations show that a phenomenon of coplanarity of most energetic subcores of γ -ray-hadron families found in mountain-based and stratospheric X-ray-emulsion chamber experiments requires to introduce a coplanar particle generation with large transverse momenta in hadron interactions at superhigh energies. Some physical mechanisms are considered. A phenomenological model, which makes it possible to simulate the coplanar particle generation, is presented. Different versions of this model are considered, their features are described and compared with those of models applied by the CORSIKA package. Cosmic-ray experimental data and simulated results are compared. Conclusion on features of hadron interactions at superhigh energies and some predictions with respect to LHC experiments are made.PACS 02.70.Uu · 12.90.+b · 13.85.-t

In this paper we present a description of the new complex installation for the study of extensive air showers which was created at the Tien Shan mountain cosmic ray station, as well as the results of the test measurements made there in 2014-2016. At present, the system for registration of electromagnetic shower component consists of ∼100 detector points built on the basis of plastic scintillator plates with the sensitive area of 0.25m 2 and 1m 2 , spread equidistantly over ∼10 4 m 2 space. The dynamic range of scintillation amplitude measurements is currently about (3 − 7) · 10 4 , and there is a prospect of it being extended up to ∼10 6 . The direction of shower arrival is defined by signal delays from a number of the scintillators placed cross-wise at the periphery of the detector system. For the investigation of nuclear active shower components there was created a multi-tier 55m 2 ionization-neutron calorimeter with a sum absorber thickness of ∼1000g/cm 2 , typical spatial resolution of the order of 10cm, and dynamic range of ionization measurement channel about ∼10 5 . Also, the use of saturation-free neutron detectors is anticipated for registration of the high-and lowenergy hadron components in the region of shower core. A complex of underground detectors is designed for the study of muonic and penetrative nuclear-active components of the shower.The full stack of data acquisition, detector calibration, and shower parameters restoration procedures are now completed, and the newly obtained shower size spectrum and lateral distribution of shower particles occur in agreement with conventional data. Future studies in the field of 10 14 − 10 17 eV cosmic ray physics to be held at the new shower installation are discussed.