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The galactic cosmic rays (GCR) is usually defined as flows of ultra-relativistic charged particles that fill the interstellar space. Cosmic rays are presented with hadrons and leptons components. Hadron (otherwise - nuclear) GCR component consists of nucleus of chemical elements starting with protons (hydrogen nucleus) to the nucleus, much heavier than iron core, and antiprotons (heavier antinucleus have not been found yet). Lepton component consists of electrons and positrons. Although the hadron component is strongly dominates, the presence of lepton components is also very important for understanding the nature of cosmic rays, since it may contain important information about the nearest sources of cosmic rays.

GCR is one of the most important component of the interstellar medium, if only because their spatial energy density (about 1.5 eV / cm3) is comparable to the energy density of interstellar electromagnetic radiation field (from the microwave background to the ultraviolet radiation of stars - about 1 eV / cm3), with the energy density of the magnetic field (6 QGSM field in the solar area corresponds to the energy about 1 eV / cm3) and the average density of the kinetic energy of the interstellar gas (~ 1 eV / cm3). Because of this, the GCR nuclear component itself requires the most careful and comprehensive examination at least in terms of potential practical applications - from issues of radiation safety of space flight and space materials to the evolution theory and the origin problems of life. The knowledge of GCR nuclear component is the basis for calculating of secondary particles fluxes, such as diffuse cosmic gamma radiation, fluxes of atmospheric muons and neutrinos. All of this is important for the solution of various problems of astrophysics.

The origin of cosmic rays is the most important theoretical problem. The energy spectrum of cosmic rays in a wide energy range - from about 10¹⁰ eV to 10²⁰ eV per particle, over 10 orders of magnitude, has a form quite close to the incident power function with an exponent of about 2.5 to slightly more than three (changes throughout this energy range). In the early 1960s, V.L. Ginzburg and S.I. Syrovatsky had shown earnestly that the main features of the cosmic rays behavior, including a full range of energy and power energies, are in good agreement with the assumption that the main source of GCR are shells of supernova explosions. In the late 1970s, this assumption was reinforced by the particle acceleration theory and the shock of the expanding supernova shell by G.F.Krimskiy and A.P.Bell. From which it followed that the particle acceleration in supernova shells should lead to the power spectrum of energy with the universal indicator, close to the two, which together in terms of the leakage of cosmic rays from the Galaxy lead to the observed energy spectrum.

Today the theory of cosmic rays origin in supernova remnants is generally accepted. In spite of that, many features of CR physics are not understood, and also there are a lot of ambiguities and contradictions for observed behavior of cosmic rays. The most famous feature of the CR spectrum, which violates a simple power behavior, is the so-called "knee" of cosmic rays. It’s the spectrum fracture near the 3x10¹⁵ eV energy. It was discovered by SINP MSU employees – G.B.Christiansen and G.V. Kulikov in 1958 when they analyze the CR spectrum with the use of indirect methods of extensive air showers (EAS). The nature of knee is not quite clear so far. Is it an indicator of the limit of CR acceleration in the shells of supernova, or perhaps it is a consequence of some features of CR extension in the Galaxy - all of these issues continue to be debated. In this connection the research of behavior details of the CR chemical composition near the knee is gaining the importance. Until now, the knee is studied only by indirect EAS methods, but these methods give only poor and approximate information about CR chemical composition. A much more accurate information (with individual charge-particle resolution) can be obtained with the use of so-called direct method, where the CR particles recorded not indirectly by monitoring the development of extensive air showers, but directly to the experimental setup - spectrometer. The spectrometer requires removal of the limits of the atmosphere for direct observation of cosmic rays, which is achieved in the high-altitude balloon experiments in space missions. The NUCLEON tool is precisely the space spectrometer, designed in particular for the study of chemical composition and spectra of individual nucleus near the knee. However, this is not the only scientific mission of NUCLEON Observatory.

The NUCLEON spectrometer can be useful in solving the following existing and actual problems:

1. The ATIC experiment indicated the non-power behavior of the energy spectra of protons and helium in the energy range 200-400 GeV / nucleon in the form of spectrum deflection. This result was later confirmed indirectly in CREAM experiment, directly observed in the form of a rather sharp fracture in PAMELA experiment, but the AMS-02 experiment significantly showed a power-law behavior of the spectra (Fig. 1).

Fig. 1

There is a contradiction in the experimental results, which may be solved with the use of new experiments, including the NUCLEON.

2. ATIC and CREAM experiments disclose a violation of power-law behavior in the spectra of heavy nucleus at energies scale of 500 GeV / nucleon in the form of spectra stuffing, but the result in both cases is not provided enough with statistics (Fig. 2 and 3). TRACER experiment was not directly confirmed this phenomenon, but also It was not in obvious contradiction with him, since statistics was not enough for certain statements. The existence of the effect should be tested with the use of higher statistics.

Fig. 2 Spectra stuffing of heavy nucleus in ATIC experiment

Fig. 3. Spectra stuffing of heavy nucleus in CREAM experiment

3. The ratio of streams of secondary to primary nucleus, as B/C, carry important information on the distribution of the nucleus in the Galaxy, and must be carefully measured to a higher energy as possible. Meanwhile, there are sufficiently reliable experimental data for the B/C ratio only up to energies of about 30-40 GeV / nucleon, where data from different experiments are consistent with each other. There are measurements at higher energies, but part of the data (Pamela, AMS-02) is preliminary and has not been published yet. Other data have low statistical reliability and indicate the different behavior of ratio (either it falls or begins to grow, Fig. 4). Data at high energies are severely lacking.

Fig. 4. The B/C ratio as a result of various experiments.

4. There was a sudden fracture instead of the expected stable fall in the HEAO-2-C2, ATIC and TRACER experiments in the flows ratio of heavy nucleus, containing a large proportion of secondary components to the iron flow (Fig. 5). The result has a low statistical reliability. It should be noted that the received result is qualitatively consistent with the results for TRACER B/C experiment, which has a low statistical significance (there is a fracture in the dependence). But it contradicts with a good statistical support of AMS-02 data (no fracture), however the data have a preliminary nature. The situation is very complicated. The existence of fracture in the flow ratio of heavy nucleus to the iron flow should be tested in new experiments with significantly improved statistics.

Fig. 5. The fracture in the flow ratio of heavy nucleus to the iron flow.

5. There is an unexpected deflection in a ratio of the heavy nucleus to the iron core (C/Fe, O/Fe) in ATIC and TRACER experiments. But the statistical reliability of the effect is not low (Fig. 6). The existence of the effect must be tested in new experiments.

Fig. 6. The deflection in the ratio of O/Fe flows according to ATIC and CREAM experiments.

6. The experimental data for the energy spectrum of cosmic ray protons indicates the possibility of spectrum fracture (the "knee") in the area of 10-20 TeV energy, but the effect is poorly provided both statistically and methodologically (data from different experiments in poor agreement). See Fig. 7 and Fig. 8. The possibility of fracture should be tested in new experiments.

Fig. 7. Possible fracture in the proton spectrum near 10-20 TeV - early experiments (before ATIC and CREAM)

Fig. 8. Possible fracture in the proton spectrum near 10-20 TeV – ATIC, CREAM and some others experiments.

7. Experimental information about the spectrum of CR electrons at energies above 200 GeV is highly contradictory. ECC (Nishimura et. Al), PPB-BETS and ATIC experiments indicate the existence of heavy bump in the 200-600 GeV. PAMEALA and AMS-02 experiments show the power-law behavior of the spectrum. Fermi, HESS and MAGIC experiments lead to medium result (Fig. 9). Obviously, we need a new measurement to produce a well provided result (statistically and methodologically) on the form ratio of the electron energy spectrum at high energies.

Fig. 9. The spectrum of electrons and positrons of cosmic rays according to different experiments

(the fig. should be updated - no AMS-02 data)

8. The ATIC experiment was detected the thin structure of the spectrum of electrons at energies above 200 GeV, which can be observed only in the presence of a high-resolution spectrometer the energy (no less than 10%) and with the use of sufficiently thin binning of the energy (no more than the same 10%). See. Fig. 10. Adequate conditions of spectrum measurement have not been provided yet in none of experiments, except the ATIC experiment. That’s why the existence of thin structure, discovered in ATIC experiment, has not been verified. The existence of this effect should be tested in new experiments. It should be noted also that the thin structure was found on the border of statistical significance (three standard deviations). The statistical significance needs to be improved in any case.

Fig. 10. Thin structure of spectrum of electrons and positrons according to data of ATIC experiment.

It should be noted that all phenomena, listed in paragraphs 1-8, have a great theoretical importance (if they exist). None of them has no generally accepted theoretical explanation and Its research can make a great contribution to the understanding of the origin of cosmic ray physics. NUCLEON experiment can give a significant contribution to the study of all these phenomena and also it can solve other problems.