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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.

The development of nuclear-electromagnetic cascade models in air in the late forties have shown informational content of the study of cores of extensive air showers (EAS). These investigations were the main goal in different experiments which were carried out over many years by a variety of methods. Outcomes of such investigations obtained in the HADRON experiment using an X-ray emulsion chamber (XREC) as a core detector are considered. The N e spectrum of EAS associated with γ-ray families, spectra of γ-rays (hadrons) in EAS cores and the N e dependence of the muon number, N µ , in EAS with γ-ray families are obtained for the first time at energies of 10 15-10 17 eV with this method. A number of new effects were observed, namely, an abnormal scaling violation in hadron spectra which are fundamentally different from model predictions, an excess of muon number in EAS associated with γ-ray families, and the penetrating component in EAS cores. It is supposed that the abnormal behavior of γ-ray spectra and N e dependence of the muon number are explained by the emergence of a penetrating component in the 1st PCR spectrum 'knee' range. Nuclear and astrophysical explanations of the origin of the penetrating component are discussed. The necessity of considering the contribution of a single close cosmic-ray source to explain the PCR spectrum in the knee range is noted.

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