## 1 Introduction
During operation, a significant data bank with information on the electron-photon, hadron, and muon components of detected showers has been accumulated, which makes it possible, in contrast to XREC, to estimate the primary energy and other lateral-energy characteristics of each EAS. The EAS core mainly consists of a stream of hadrons generated in a series of successive interactions of a primary particle in the atmosphere. Secondary particles, if their energy is high enough, in turn also generate particles of next generations and their own \"subcores\", from which the EAS core is formed. Hadrons in subcores are concentrated around the trajectory of the particle that generated them in a rather narrow cone. If one considers the hadron structure of the EAS core in the target plane at the observation level, then at a high lateral resolution this will be a hadron flux of mainly not very high energies, which will not exceed the detection threshold of the XREC. As the resolution deteriorates, it becomes impossible to single out individual hadrons, but it is possible to single out individual subcores (jets) that often overlap with each other and belong to hadrons of earlier generations and higher energies. The larger structures are considered, the higher energies and earlier generations of particles can be revealed if it is possible to register the integral energy fluxes within such jets and if the installation area is sufficient for this. In principle, the EAS core, without taking into account its structure, carries information about the primary particle. It should also be taken into account that, when passing through the atmosphere, all subcores irreversibly lose energy, mainly for the generation of electron-photon and muon components. The BIC registered the total energy released in its absorber by EAS core hadrons, regardless of the energies of individual hadrons. The summation was carried out within each registration channel (ionization chamber) with dimensions of 0.25 m\({}^{2}\). With a channel width of 25 cm, the lateral resolution of the BIC for hadronic cascades is 50-75 cm, which does not allow one to separate individual hadrons, but does not interfere with the study of the large-scale structure of the EAS core. Events with an energy of the primary particle \(E_{0}>100\) TeV and an energy release in the calorimeter \(E_{c}>10\) TeV were selected for analysis. This guaranteed, with a high probability, that the EAS core would hit the calorimeter. The BIC had 19 rows of ionization chambers, interlayered with lead with a total thickness of about five mean free paths for nuclear interaction, and the carbon target of one more mean free path thick was located above it. The axes of the chambers in neighboring rows are directed perpendicular to each other, so the three-dimensional picture of the location of the jets in the calorimeter is represented as two projections on its side faces. It was shown in that, as the depth increases, the substructures of the EAS core become more pronounced in the calorimeter. Namely, the jets become narrower, their number decreases, and the most energetic jets reach great depths. Therefore, when selecting jets, only the ionization registered under the absorber layer with a total thickness of at least five nuclear ranges was considered. Preliminary results have indicated the presence of the effect in large-scale hadronic structures in the cores of high-energy extensive air showers at the level of six standard deviations above the background [25]. The share of such events grows with increasing energy and the amounts average approximately 25% in the energy range of 0.1-10 PeV. Thus, the new ionization calorimeter considered below, which is thicker than the BIC, will make it possible to study the above problem in more detail. It is very difficult to explain, by cascade fluctuations, the entire set of experimental results related to the coplanarity of hadron generation, since the corresponding probability is very low (\(\lesssim\)10\({}^{-10}\)) [26; 27; 28].