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The aim of the NUCLEON space experiment was to measure spectra of high-energy cosmic rays. Direct measurements of energy spectra of protons and nuclei of cosmic rays which allow separating particles in charge are required to solve important astrophysical problems. The satellite was launched on December 26, 2014, and operated for three years. Measured spectra of protons and alpha particles in the energy range of 2–500 TeV per particle have been presented. The results have been analyzed and compared to other experimental data for lower energies. The ratio of fluxes of protons and alpha particles is nearly constant in a wide range of magnetic rigidities (3–100 TV). Thus, the behavior of the ratio of the spectra is significantly different from a similar dependence in the region of lower magnetic rigidities measured in other experiments. One of the possible explanation of this effect can be given within a model with one close source.

The NUCLEON-2 experiment is aimed at the investigation of isotope and charge composition of medium, heavy and ultra-heavy ions ( Z 82 ) in the 300 MeV/N - 1 GeV/N energy range. The concept design of HICRS for the NUCLEON-2 satellite cosmic ray experiment is presented. The performed simulation confirms the isotope resolution algorithms and techniques. Argon isotopes’ resolution in the NUCLEON-2 prototype is presented.

The NUCLEON experiment is aimed to investigate the composition and energy spectra of high energy cosmic rays. Direct measurements of the energy spectra of cosmic ray protons and nuclei over the range of 1–100 TeV are very important for the solution of a general astrophysical problem of origin of cosmic rays. The satellite was launched on 26 December 2014. The measured charge composition is analyzed and compared with data obtained by other experiments at lower energies. The proton to helium ratio is close to constant over the wide magnetic rigidity area (3–100 TV). The charge composition dependence on magnetic rigidity can be explained by means of the single source model.

Some results of studies of cosmic rays obtained during the NUCLEON space experiment in 2015–2017 are presented. This experiment was intended for direct measurements of the energy spectra and chemical composition of cosmic rays (Z = 1−30) in the energy range 2–500 TeV. Results presented include energy spectra for various abundant nuclei measured using the new Kinematic Lightweight Energy Meter (KLEM). The primary energies are established using the spatial densities of secondary particles produced in inelastic interactions with a carbon target.

The main aims of the NUCLEON satellite experiment are direct measurement of the energy spectra of cosmic ray protons and nuclei in the 2–500 TeV range of energies by two different methods (an ionization calorimeter and the new Kinematic Lightweight Energy Meter (KLEM) technique). The energy spectra of protons and helium nuclei are presented, and their characteristics are discussed.

The NUCLEON space observatory was developed to measure the spectra of cosmic ray nuclei with individual charge resolution in the energy range of several TeV to 1 PeV per particle. The NUCLEON was launched into a heliosynchronous orbit as an additional load on the Resurs-2P production satellite on December 28, 2014, and it is still in operation (2019). This work is a brief review of the results from the NUCLEON observatory over three years of operation in orbit. The spectra of the main primary abundant nuclei and product nuclei of cosmic rays (CRs) are presented. Some new interesting features of the CR spectra found in the NUCLEON data are discussed.

The NUCLEON experiment aims to study chemical composition and energy spectra of galactic cosmic rays for nuclei charges Z = 1 − 30 and energies 10 11 − 10 15 eV. The research is conducted with the help of the NUCLEON scientific equipment installed on the Russian satellite “Resurs-P” No. 2 as an additional payload. This article describes the results of the first year of the space experiment NUCLEON, including methodological features of data acquisition mode setup, evaluation of the equipment’s performance and methods it provides, as well as preliminary results of data analysis.

The NUCLEON space observatory is a direct cosmic ray spectrometer designed to study cosmic ray nuclei with Z = 1 - 30 at energies 10 12 - 10 15 eV. It was launched as an additional payload onboard the Russian Resource-P No. 2 satellite in December of 2014. In this work B/C, N/O and subFe/Fe ratios are presented. The experiment has worked for half of its expected time, so the data have preliminary status, but they already give clear indications of several astrophysical phenomena, which are briefly discussed in this paper.

The NUCLEON-2 experiment is aimed at the investigation of isotope and charge composition of ions from carbon up to trans-uranium elements in the energy range over about a hundred MeV/N. The concept design of the NUCLEON-2 satellite cosmic ray experiment is presented. The performed simulation and preliminary prototype beam test confirms the isotope resolution algorithms and techniques.

The NUKLON-2 experiment is aimed at measuring the isotope and charge composition of cosmic rays for medium, heavy, and superheavy ions (Z < 82) with energies between 300 MeV/nucleon and 1 GeV/nucleon. The design of the planned satellite-borne NUKLON-2 cosmic-ray detector is presented. Modeling of the detector’s performance indicates the adopted isotope-separation techniques are effective.

One of the most important results from the ATIC experiment is its collection of the energy spectra of abundant cosmicray nuclei: protons, He, C, O, Ne , Mg, Si, and Fe, measured in terms of energy per par� ticle in the energy range of 50 GeV to tens of TeV. Starting with the spectra measured in the ATIC experiment, abundant nuclei spectra in sources are calculated using a number of propagation models. The results from comparing the spectra in sources of different nuclei are shown to depend only weakly on the propagation model. The spectrum of helium in sources is found to be harder than that of protons; this result is of high sta� tistical significance and is virtually modelindependent. From helium up to iron nuclei, the steepness of the spectra in sources is seen to grow notably as the charge of nuclei rises.

The NUCLEON space experiment was designed to measure energy spectra of cosmic ray nuclei from protons to iron in the energy range approximately from 1 TeV per particle to 1 PeV per particle with good individual charge resolution. The apparatus started the collection of data at the beginning of 2015 and it is in operation up to now. The duration of the mission is expected to be no less than five years. One of the main feature of the experiment is an implementation of two different methods of energy measurement on board of the apparatus -- the calorimetric method and the new kinematic KLEM method (Kinematic Lightweight Energy Meter). The data obtained after two years of operation are presented. A multiple signs of complex behavior of the nuclei spectra and the ratios of spectra violating of a simple universal power-law behavior of the spectra will be presented in the report.

The NUCLEON-2 experiment is aimed at the investigation of isotope and charge composition of medium, heavy and ultra-heavy ions (Z < 82) in the 300 MeV/N — 1 GeV/N energy range. The concept design of HICRS for the NUCLEON-2 satellite cosmic ray experiment is presented. The performed simulation confirms the isotope resolution algorithms and techniques.

The NUCLEON satellite experiment is designed to investigate directly the energy spectra of cosmic-ray nuclei and the chemical composition (Z=1−30) at energy range 100 GeV–1000 TeV. The satellite has been launched in 26 December 2014. The planned exposition time is more than 5 years. The first preliminary results are presented including charge distributions and all particles energy spectra

One of the main results of the ATIC (Advanced Thin Ionization Calorimeter) experiment is a collection of energy spectra of abundant cosmic-ray nuclei: protons, He, C, O, Ne, Mg, Si, Fe measured in terms of energy per particle in the energy range from 50 GeV to tens of teraelectronvolts. In this paper, the ATIC energy spectra of abundant primary nuclei are back-propagated to the spectra in sources in terms of magnetic rigidity using a leaky-box approximation of three different GALPROP-based diffusion models of propagation that fit the latest B/C data of the AMS-02 experiment. It is shown that the results of a comparison of the slopes of the spectra in sources are weakly model dependent; therefore the differences of spectral indices are reliable data. A regular growth of the steepness of spectra in sources in the range of magnetic rigidity of 50--1350~GV is found for a charge range from helium to iron. This conclusion is statistically reliable with significance better than 3.2 standard deviations. The results are discussed and compared to the data of other modern experiments., 8 pages, 11 figures

The ratios of heavy nuclei from Sulfur (Z=16) to Chromium (Z=24) fluxes to the flux of iron nuclei were measured recently in the ATIC-2 experiment. These ratios were the decreasing functions of energy from 5 GeV/n to approximately 50 GeV/n as expected. However, an unexpected sharp upturn in the ratios was observed at energy ∼ 50 GeV/n. In this paper, we revise the data and show that the statistical confidence of the observed upturn in the ATIC data is 99.7% and some additional argumets supporting the phenomenon are presented. A possible cause of the upturn is discussed and it is demonstrated that it can be partially understood within a model of ‘Closed Galaxy with Bubbles’ (CGB). Some features and problems of the CGB model are discussed.

in the energy range from 50 GeV to tenths of TeV. In this report the ATIC energy spectra of abundant nuclei are back propagated to the spectra in sources in terms of magnetic rigidity using a number of GALPROP-based models of cosmic rays propagation. It is shown that the results of comparison of the slopes of the spectra are relatively weakly model-dependent within a set of studied models. It is shown that the helium spectrum in sources is flatter than the proton spectrum with high statistical significance. A regular growth of steepness of the spectra is found for a charge range from helium to iron, and this conclusion is also statistical significant. The results are discussed and compared with data of other modern experiments

The purpose of the ATIC balloon experiment is to measure the energy spectra of primary cosmic rays with individual charge resolution from protons to iron over the energy range from ∼50 GeV to 200 TeV. The particle energy is measured by a bismuth germanate (BGO) scintillation calorimeter. The procedure of calorimeter calibration is described, in particular, calibration of the temperature dependence of the calorimeter sensitivity using the data of in-flight measurements. A technique for determining the energy deposited in the calorimeter in view of the temperature dependence of its sensitivity is presented. The maximum systematic error in determining the deposited energy by the calorimeter is 10% or less, and the probable error is estimated at 6%.

The Advanced Thin Ionization Calorimeter (ATIC) experiment is designed to investigate the charge composition and energy spectra of primary cosmic rays over the energy range from about 10(11) to 10(14) eV during Long Duration Balloon (LDB) flights from McMurdo, Antarctica. Currently, analysis from the ATIC-1 test flight and ATIC-2 science flight is underway and preparation for a second science flight is in progress. Charge identification of the incident cosmic ray is accomplished, primarily, by a pixilated Silicon Matrix detector located at the very top of the instrument. While it has been shown that the Silicon Matrix detector provides good charge identification even in the presence of electromagnetic shower backscatter from tile calorimeter, the detector only measures the charge once. In this paper, we examine use of the top scintillator hodoscope detector to provide a second measure of the cosmic ray charge and, thus, improve the ATIC charge identification. (c) 2007 COSPAR. Published by Elsevier Ltd. All rights reserved.

This paper reports on the results of measurements performed in the course of the ATIC-2 balloon experiment (2002–2003) for the energy spectra of particles (such as protons; He, C, O, Ne, Mg, Si, and Fe nuclei; and some groups of nuclei) and the all-particle energy spectrum in primary cosmic rays at energies ranging from 50 GeV to 200 TeV. The conclusion is drawn that the energy spectra of protons and helium nuclei differ substantially (the spectrum of protons is steeper) and that the shape of the energy spectra of protons and heavy nuclei cannot be described by a power function.

The Advanced Thin Ionization Calorimeter (ATIC) balloon-borne experiment is designed to perform cosmic-ray elemental spectra measurement from 50 GeV to 100 TeV for nuclei from hydrogen to iron. These measurements are expected to provide crucial hints about some of the most fundamental questions in astroparticle physics today. ATTIC'S design centers on an 18 radiation length (X(sub Omnicron)) deep bismuth germanate (BGO) calorimeter, preceded by a 0.75 lambda(sub int) graphite target. In September 1999 the ATIC detector was exposed to high-energy beams at CERN's SPS accelerator, within the framework of the development program for the Advanced Cosmic-ray Composition Experiment for the Space Station (ACCESS). In December 2000 - January 2001, ATIC flew on the first of a series of long duration balloon (LDB) flights from McMurdo Station, Antarctica. We present here results from the 1999 beam-tests, including energy resolutions for electrons and protons at several beam energies from 100 GeV to 375 GeV, as well as signal linearity and collection efficiency estimates. We show how these results compare with expectations based on simulations, and their expected impacts on mission performance.

It is argued that the upturn observed in heavy nuclei to iron ratios as measured in the ATIC experiment can be understood within a model of a closed galaxy with embedded local regions containing sources of cosmic rays. This model predicts a universal upturn near energies of 200–300 GeV/nucleon in the spectra of abundant primary nuclei. It also predicts the source spectral index to lie near 2.5.

The Advanced Thin Ionization Calorimeter (ATIC) was built for series of long- duration balloon flights in Antarctica. Its main goal is to measure energy spectra of cosmic ray nuclei from protons up to iron nuclei over a wide energy range from 30 GeV up to 100 TeV. The ATIC balloon experiment had its first, test flight that lasted for 16 days from 28 Dec 2000 to 13 Jan 2OO1 around the continent. The ATIC spectrometer consists of a fully active BGO calorimeter, scintillator hodoscopes and a silicon matrix. The silicon matrix, consisting of 4480 pixels, was used as a charge detector in the experiment. About 25 million cosmic ray events were detected during the flight. In the paper, the charge spectrum obtained with the silicon matrix is analyzed.

A strong anomaly in form of a wide peak in the energy range 300–800 GeV was discovered in the first measurements of the electron spectrum in the energy range from 20 GeV to 3 TeV by the balloon-borne experiment ATIC [1]. The experimental data processing and analysis of the electron spectrum with different criteria for selection of electrons completely independent of the results reported in [1] is employed in the present paper. New independent analysis generally confirms the results of [1] but shows that the spectrum in the region of the anomaly is represented by a number of narrow peaks. Measured spectrum is compared to the spectrum of [1] and to the spectrum of the Fermi/LAT experiment.

Titanium is a rare, secondary nucleus among Galactic cosmic rays. Using the Silicon matrix in the ATIC experiment, Titanium has been separated. The energy dependence of the Ti to Fe flux ratio in the energy region from 5 GeV per nucleon to about 500 GeV per nucleon is presented., Comment: 8 pages, 4 figures, accepted for publication in Astronomy Letters

The final results of processing the data from the balloon-born experiment ATIC-2 (Antarctica, 2002-2003) for the energy spectra of protons and He, C, O, Ne, Mg, Si, and Fe nuclei, the spectrum of all particles, and the mean logarithm of atomic weight of primary cosmic rays as a function of energy are presented. The final results are based on improvement of the methods used earlier, in particular, considerably increased resolution of the charge spectrum. The preliminary conclusions on the significant difference in the spectra of protons and helium nuclei (the proton spectrum is steeper) and the non-power character of the spectra of protons and heavier nuclei (flattening of carbon spectrum at energies above 10 TeV) are confirmed. A complex structure of the energy dependence of the mean logarithm of atomic weight is found., Comment: 4 pages, a paper for 30th Russian Cosmic Ray Conference (2008, St. Petersburg)

New analysis to separate electrons from protons in the ATIC experiment has been performed. Five new discriminants were studied by different Monte Carlo programs. New electron spectrum, when compared with the published results [1], show good agreement in the most interesting region of energy (from 90 GeV to 600 GeV). It is argued that there is no disagreement between ATIC’s results and Fermi-LAT ones. Finally, high-resolution electron spectrum is obtained and possible fine structure is found out in it. The ATIC (Advanced Thin Ionization Calorimeter) balloon-borne spectrometer was designed to measure the energy spectra of elements from H to Fe with individual resolution of charges in primary cosmic rays for energy region from 50 GeV to 100 TeV. ATIC has had three successful flights around the South Pole in 2000–2001 (ATIC-1), 2002-2003 (ATIC-2) and 2007-2008 (ATIC-4). ATIC is comprised of a fully active bismuth germanate (BGO) calorimeter, a carbon target with embedded scintillator hodoscopes, and a silicon matrix that is used as the main charge detector. The calorimeter is comprised of 8 layers with 40 BGO crystalls in each for ATIC-1 and ATIC-2 and of 10 layers for ATIC-4. The details of the construction of the apparatus are described in the papers [2–4]. It was shown that it is possible also to measure the spectrum of cosmic ray electrons plus positrons [5] with ATIC (hereinafter we use ’electrons’ for brevity). To separate electrons from the higher background of protons and other nuclei some differences in shower development for incident electrons and for nuclei are used. The spectrum of electrons measured with the ATIC spectrometer by this method was published in the paper [1]. The most notable detail of the electron spectrum reported was an ‘excess’ of electrons between energies of 300–800 GeV. The main purpose of this work is to investigate possible alternate techniques to separate electrons from hadrons and was curried ae-mail: panov@dec1.sinp.msu.ru E, GeV 2 10 3 10 ) 2 G eV -1 st er -1 s -2 (m 3

The energy spectra of abundant heavy nuclei from carbon to iron collected by the NUCLEON space experiment after two years of operation are presented. The spectra were measured with use of both calorimeter and KLEM methods. The complex behavior of the spectra from carbon to silicon in the energy range from a few TeV to hundreds of TeV per particle is presented and discussed. The difference between the spectrum of iron and the spectra of other heavy nuclei from carbon to silicon and a signature of a universal break in the spectra of all nuclei near the magnetic rigidity 10 TV are emphasized. Some new features in the spectra of heavy nuclei are discussed.