卷 82, 编号 6 (2019)

In the past decades, considerable advances have been made both in experimentally studying and in theoretically describing properties of cold nuclear matter at short nucleon-nucleon distances. In the present study, it is shown that, in addition to the commonly known method of studying the structure of nuclei at short distances in processes of deep-inelastic lepton scattering, processes of particle production in nucleus-nucleus reactions beyond the kinematics of nucleon-nucleon collisions are an important complementary source of information. Some predictions concerning the behavior of special features that are peculiar to such processes and which one can extract from experimental data obtained for collisions of gold nuclei at an energy of 2.4 GeV in the HADES experiment at the GSI (Gemeinschaft für Schwerionenforschung) research center (Darmstadt, Germany) are presented.

Ground-state properties of even-even nuclei were calculated over a broad region of mass numbers, including nuclei that contain a neutron excess in the vicinity of the neutron drip line. The calculation of the properties of such nuclei relied on the method of the relativistic and the nonrelativistic mean field and took into account the axial deformation of nuclei. Particular attention was given to nuclei beyond the theoretical neutron drip line, which form a peninsula of nuclei in the (N, Z) space at N = 184 that are stable against the emission of one or two neutrons.

In the present work, we reanalysis the ¹²C + ¹²C refractive scattering over a wide energy range. The analysis is performed in the framework of optical model with the solution of the non-relativistic Schrödinger equation. For the real part of the optical model potential, we used real folded potentials based on JLM effective nucleon-nucleon (NN) interaction. For the imaginary part we used the familiar and conventional Woods-Saxon (WS) form with three adjusted parameters. Different local density approximations (LDA) are used for JLM effective NN interaction. Our main purpose is to find a systematic optical model potential over a wide energy range between 70.7 and 1440 MeV. The real JLM folded potentials with a shallow WS imaginary potentials successfully and systematically reproduced the general feature of the refractive elastic scattering of ¹²C + ¹²C. The energy dependence of the real (J_R) and imaginary (J_I) volume integrals and reaction cross sections σ_R is investigated.

Differential cross sections for the production of nuclear fragments at an angle of 3.5° in the fragmentation of 2-GeV/nucleon carbon ions on a beryllium target were measured in the FRAGM experiment performed at the ITEP-TWA heavy-ion accelerator-accumulator complex. The predictions of four Monte Carlo models of ion-ion interactions (BC, INCL, LAQGSM, and QMD) were tested on the basis of a comparison with the momentum spectra of fragments. Successes and drawbacks of these models are discussed. The energy spectra of protons and ³He nuclei in the cumulative region in the projectile rest frame are well described by an exponential dependence, which make it possible to estimate temperature parameters of their emission source.

A reanalysis of experimental data from the RUssia-Nippon JOint Balloon (RUNJOB) emulsion experiment on the basis of a new method aimed at searches for primary galactic particles in events identified as those of nucleon-nucleus interaction confirmed the original result that consisted in the absence of a large number (about 50%) of tracks of incident particles. A comparative analysis of such events where there is a detected primary track and where there is no primary track was performed in terms of the energy, angular distribution, and depth of penetration into x-ray emulsion chambers (XREC). The hypothesis that a neutral component is present in cosmic rays at the XREC exposure level is discussed.

The work is dedicated to the discussion of four new types of large-area scintillation counters design intended for detection of EAS and the use in the guard systems of experimental physics setups with low-cost production. The solid counters based on scintillating polystyrene plates are produced by melting clear polystyrene granules with additives in a mirror mold. Other counters are based on lentil-like polystyrene scintillation granules which are a new kind of plastic scintillators produced at IHEP. WLS fibers and SiPM as a photo sensor are used for a light detection. The dimensions of the tested detectors were 500 × 500 and to 1000 × 1000 mm², their measured light output was up to 180 ph.e.

Lateral distribution of cascade particles was studied in extensive air showers initiated by cosmic rays with energy above 10¹⁷ eV. The study is based on the data collected with ground-based scintillation detectors of the Yakutsk array during the continuous observational period from 1977 to 2017. Particle density measured in experiment is compared to the results of simulations performed for primary protons and iron nuclei within the framework of four ultra-high energy hadronic interaction models. Particle density obtained in the simulation was converted to signal of the scintillation detectors of the array. From the parameters of the resulted lateral distribution function, features of extensive air showers longitudinal development were derived.

The lateral distribution of cascade particles was studied in extensive air showers initiated by cosmic rays with energies above 10¹⁷ eV. The study is based on experimental data of ground-based and ground-shielded (with ∼1-GeV energy threshold) scintillation detectors of the Yakutsk EAS array collected during the continuous observational period from 1977 to 2017. Particle density measured in experiment is compared to the results of simulations performed with the use of several ultra-high energy hadron interaction models. The best agreement between theory and experiment was obtained for qgsjet01 and qgsjet ii-04 models. Interpretation of our data has indicated that within the energy range (1–30) × 10¹⁷ eV the cosmic ray mass composition changes from nuclei of intermediate group towards protons.

One of the uncertainties in the interpretation of ultra-high-energy cosmic-ray (UHECR) data comes from the high-energy hadronic interaction models used for air shower Monte-Carlo (MC) simulations. A long-standing problem of the so-called “muon excess”, the discrepancy of number of muons predicted by simulations and observed in the data, is believed to be caused by the incompleteness of modern hadronic interaction models, all of which are known to use the extrapolated values of the parameters of hadronic interactions, such as cross sections and multiplicities. The present work is dedicated to the study of muon densities in UHE extensive air showers from the Telescope Array experiment surface detector data. In the 7-year-data from the Telescope Array experiment, we find that the number of particles observed for signals with an expected muon purity of ∼65% at a lateral distance of 2000 m from the shower core is 1.72 ± 0.10(stat.) ± 0.37(syst.) times larger than the MC prediction value using the QGSJETII-03 model for the proton-induced showers. A similar effect is also seen in comparison with other hadronic models such as QGSJETII-04, which shows a 1.67 ± 0.10 ± 0.36 excess. We also studied the dependence of these excesses on lateral distances and found a slower decrease of the lateral distribution of muons in the data as compared to the MC, causing larger discrepancy at the larger lateral distances.

The Sydney University Giant Air-shower Recorder(SUGAR) measured the energy spectrum of ultra-high-energy cosmic rays reconstructed from muon detector reading. Comparison of their spectra SUGAR and Pierre Auger Observatory allows us to reconstruct the empirical dependence of the number of muons in a vertical shower on the primary energy for energies between 10¹⁷ and 10¹⁸ eV. We compared this dependence with the predictions of hadronic interaction models QGSJET-II-04, EPOS-LHC and SIBYLL-2.3c. In addition, we analyzed the response of the array of muon detectors in order to determine the slope of the muon lateral distribution function. It is important to understand how much the number of muons differs from the predictions of modeling at different distances from the shower axis.

Analysis of the isotope composition of nuclei in galactic cosmic rays (GCR) in the PAMELA orbital international experiment allows studying the problems of cosmic-ray origin and propagation in our Galaxy. PAMELA magnetic spectrometer data provided the significant progress in the study of the light nuclei isotope composition of GCR from H to Be in the energy range ∼0.1–1 GeV/nucleon. This makes it possible to estimate the contribution of local (∼100 pc) young (∼10⁶ years) interstellar sources (LISS) into GCR fluxes from supernova explosions. The analysis of boron (B) isotope fluxes in the GCR has so far been carried out only in the energy range ∼0.08–0.17 GeV/nucleon in the space experiments Voyager, Ulysses, ACE. In the present contribution the attempt was done to determine the ¹¹B/¹⁰B ratio in the energy range ∼0.1–1.0 GeV/nucleon for the first time on the base of 2006–2014 PAMELA data using the measurements of the detected nuclei rigidities, velocities and ionization losses in a multilayer calorimeter. The new PAMELA results are consistent with existing as experimental data and those expected from simulations. However the statistical and systematic measurement uncertainties do not allow to separate the local boron source contributions into GCR fluxes. The preliminary results of the boron isotope flux analysis in GCR (¹⁰B, ¹¹B spectra and ¹¹B/¹⁰B ratio dependences on the rigidity and energy) are presented as well as the existing measurement data and simulation results.

The recent years saw the implementation and deployment of a new generation of instruments flown in space or on stratospheric balloons. They are targeted at the study of a variety of energetic cosmic particles, including protons and nuclei, electrons, antimatter particles (positrons and antiprotons), secondary nuclei (including isotopes), ultraheavy nuclei, all complementing gamma-ray studies. Thus a new wealth of data is providing fresh insights on high-energy phenomena in the Galaxy. The instruments are large and deployed for long exposures, providing for an energy reach that permits direct cross-comparisons with ground-based measurements. We briefly review the state of the field, focusing on present and near future efforts.

The paper presents the cosmic ray spectrum by the Small Cherenkov Yakutsk array data for 20 years of continuous observation. It has been shown by measurements that in the cosmic ray spectrum there is a break in the slope at energy ∼10¹⁷ eV. The reliability is based on the spectra of other compact array experiments and simulations to check for systematic uncertainties, which could affect the shape of the spectrum. In addition there is a change in mass composition of cosmic rays obtained from longitudinal development of air showers with energy 10¹⁶–10¹⁸ eV.

Particles of albedo radiation are the particles born in interactions of primary cosmic rays penetrating inside Earth’s atmosphere and magnetosphere and the atmosphere nuclei. These interactions result in so-called particle showers and the detection of these showers is the essence of work for ground-based cosmic-ray detectors such as neutron monitors, muon hodoscopes and EAS arrays. Some products of these interactions undergoing by scattering and having the curve paths in geomagnetic field propagate upwards to the boundary of Earth’s magnetosphere. These particles are called albedo particles. The principle of their identification is simple. They are registered in geomagnetic zones where the penetration of low-energy galactic or solar cosmic rays is restricted due to Earth’s magnetic field. The results of measurements of albedo protons, deuterons, electrons and positrons has been already published by PAMELA collaboration. In this work the first approach to search for the albedo tritium nuclei with energies above 100 MeV/nucleon is described.

During the several decades of Forbush decrease (FD) studies the main properties of this phenomenon were established. Today is clear that Forbush decreases originate as the responses of cosmic ray particle fluxes to solar-induced processes inside interplanetary space. Moreover the profiles of FD’s are the manifestation of the complex structure of coronal mass ejections (CMEs) which are driving from the Sun and often accompanied by flares. So the investigation of FD’s is a useful tool for understanding the dynamics of CME processes and the effects they have on in the interplanetary space. Classification and theoretical interpretation of different FD’s are important for understanding the complex effect of CME’s as well as the search for new features of their behavior. Spectra of cosmic ray protons and helium nuclei obtained by the PAMELA experiment in the rigidity range between 1–15 GV were used to investigate the characteristics of Forbush decreases. Additional data on the interplanetary magnetic field and solar wind speed were taken from the ACE data center for correlation analysis. Rigidity dependences for selected Forbush decreases are also presented.

In 2018, the creation of the central part of the NEVOD-EAS cluster-type array aimed at detection of the electron-photon component of extensive air showers in the energy range from 10¹⁵ to 10¹⁷ eV was completed. At present, a continuous data taking is being performed at the array. The results of the reconstruction of registered extensive air showers using the methods developed within the framework of the cluster approach to experimental data analysis are presented.

Abstract-The PAMELA magnetic spectrometer was launched onboard the Resurs-DK1 satellite to the Earth polar orbit with altitude of 350–600 km to study the fluxes of cosmic ray particles and antiparticles in a wide energy range. Starting science operation in July 2006, PAMELA spectrometer performed continuous observation without major interruption till January 2016 collected about 10 billion trigger events. New analysis included data for all period of observations in 2006–2016 with improved selection efficiency and it allows to extend measurements of total electron and positron flux in TeV region with better statistic accuracy. In this paper, the observed energy spectrum of electrons and positrons is presented and compared with the other modern measurements.

The NUCLEON satellite experiment is designed to investigate directly the energy spectra of galactic cosmic ray (CR) nuclei and its charge composition before the “knee”: in the energy interval from 100 GeV to 100 TeV and the charge range Z = 1–30 respectively. The “knee” energy range of 10¹¹–10¹⁶ eV is a crucial region for the understanding of the cosmic-ray acceleration and propagation in the interstellar medium. The NUCLEON detector has been data taken since December, 2014. The NUCLEON trigger system and CR event selection are described, including the beam tests at the SPS CERN, flight tests in orbit and the Monte-Carlo simulation.

The Yakutsk array is designed to study cosmic rays at energy 10¹⁵–10²⁰ eV. The array detects charged particles, muons, Cherenkov light and radio emission. Radio-emission method is capable to study air shower physics independently of other shower components, including energy estimation of primary particle, longitudinal development of the particle cascade in the atmosphere (in the case of the Yakutsk array the depth of maximum development X_max). For the showers with energy E ⩾ 10¹⁹ eV arrival directions were tracked and reconstructed in galactic and equatorial coordinate system to search for cosmic ray sources with such energies.

Primary cosmic ray energy spectrum around and above 1 PeV is of great interest due to its non-power-law behavior (“knee”) in PeV region found many years ago using the indirect EAS (Extensive Air Shower) method. The method is based on secondary particles measuring on Earth’s surface under a thick atmosphere. Traditionally, people use detectors sensitive to ionization produced mostly by secondary electromagnetic component and therefore any found changes in EAS size spectrum correspond to secondary components, which have to be recalculated to primary spectrum. Recently some new “knees” were claimed by high altitude experiments: at ∼45 TeV for all-particle spectrum (HAWC), for primary protons and helium: at ∼400 TeV (Tibet ASγ) and at ∼700 TeV (ARGO-YBJ) thus widening the “knee” region from ∼0.045 to 5 PeV. The natural explanation of such a strange spectrum behavior in a wide energy range could be found in the EAS phenomenological approach to the knee problem.

Cosmic ray acceleration by astrophysical shocks in supernova remnants is briefly reviewed. Results of numerical modeling taking into account magnetic field amplification by streaming instability and shock modification are presented. Nonthermal emission produced by accelerated particles in young and old supernova remnants is compared with available data of radio, X-ray, and gamma-ray astronomy. We also discuss a possibility of particle acceleration to PeV energies at supernova shocks propagating in the interstellar bubbles created by stellar winds of supernova progenitors.

A phenomenon of abnormally weak absorption of very-high-energy cosmic-ray hadrons in lead is discussed. This phenomenon was first observed in Tien-Shan high-altitude experiments in hadronic cores of extensive air showers and has encouraged to introduce the hypothesis of a so-called long-flying or penetrating cosmic-ray component. A similar effect was detected later with deep uniform lead X-ray emulsion chambers (XREC) at the Pamirs. Experiments, which are sensitive to the production of charmed hadrons in the forward kinematic region (x_Lab ≳ 0.1), have been carried out at the Tien-Shan and Pamirs with exposing two-storey XRECs with large air gaps to prove explanation of the experimental results with high charm production cross section \({\sigma _{pp \to c\bar c}} \sim 8\) at x_Lab ≳ 0.1 at ⟨E_Lab⟩ ∼ 75 TeV. This \({\sigma _{pp \to c\bar c}}\) value makes it possible to reproduce the experimental hadron-absorption curve observed with XRECs, including curve’s bending at a depth of ∼70 c.u.

Estimations of some geometrical and bulk parameters are presented for the matter produced in various type collisions with ultra-high energy cosmic ray (UHECR) particles. Results for multiplicity density at midrapidity, decoupling time, and energy density are discussed for small and larger collision systems. Based on the analytic functions suggested previously elsewhere, estimations for a wide set of space—time quantities are obtained for emission region created in various particle collisions at energies of UHECR. The space particle densities at freeze-out are derived also and allow the possibility of novel features for secondary particle production like Bose—Einstein condensation at least for nuclear interactions with UHECR particles. The estimations obtained for global and geometrical parameters indicate the creation of deconfined quark—gluon matter with large enough volume and lifetime even in light nuclear collisions at UHECR energies. These quantitative results can be important for both the future collider experiments at center-of-mass energy frontier and the improvement of the phenomenological models for development of the cosmic ray cascades in ultra-high energy domain.

The space-based GAMMA-400 gamma-ray telescope will measure the fluxes of gamma rays in the energy range from ∼20 MeV to several TeV and cosmic-ray electrons and positrons in the energy range from several GeV to several TeV to investigate the origin of gamma-ray sources, sources and propagation of the Galactic cosmic rays and signatures of dark matter. The instrument consists of an anticoincidence system, a converter-tracker (thickness one radiation length, 1 X₀), a time-of-flight system, an imaging calorimeter (2 X₀) with tracker, a top shower scintillator detector, an electromagnetic calorimeter from CsI(Tl) crystals (16 X₀) with four lateral scintillation detectors and a bottom shower scintillator detector. In this paper, the capability of the GAMMA-400 gamma-ray telescope for electron and positron measurements is analyzed. The bulk of cosmic rays are protons, whereas the contribution of the leptonic component to the total flux is ∼10⁻³ at high energy. The special methods for Monte Carlo simulations are proposed to distinguish electrons and positrons from proton background in the GAMMA-400 gamma-ray telescope. The contribution to the proton rejection from each detector system of the instrument is studied separately. The use of the combined information from all detectors allows us to reach a proton rejection of up to ∼1 × 10⁴.

A method for elimination of periodical diurnal, annual, and 27-day and 11-year solar variations in the matrix observations of the URAGAN muon hodoscope was developed. The analysis of the parameters of these variations in the time and frequency domains was performed. Two-dimensional bandpass filtering of sequences of muon hodoscope matrix observations was implemented. The structure of a two-dimensional filter is developed, based on the operation of elementwise matrix multiplications and additions. Examples of eliminating variations in the URAGAN muon hodoscope matrix observations are discussed.

Coronal mass ejections are among the most powerful disturbances of the interplanetary space. They can influence the state of the near-Earth space, including magnetosphere of the Earth. In addition, such disturbances modulate the flux of cosmic rays and penetrate both the heliosphere and the Earth’s magnetosphere. In order to find an early alert of such events, it is necessary to investigate the flux of particles arriving to the Earth and providing information about events in the heliosphere. The paper presents the results of investigation of the anisotropy of the cosmic ray muon flux by means of the muon hodoscope URAGAN in the period from 2007 to 2018.

An energy spectrum of semidiurnal variations of cosmic rays observed at the Earth is investigated. The data of registration of cosmic rays by the ground and underground multidirectional muon telescopes (stations Yakutsk, Nagoya, Hobart, Kuwait, São Martinho da Serra, Misato, Sakashita, Matsushiro), which covers the time period from 1971 to 2018 and the median energy range from 55 to 686 GeV, are used. Average annual values of semidiurnal variations of cosmic rays observed by the mentioned stations and free from atmospheric and geomagnetic effects are obtained. Based on the analysis of the obtained data, a form and temporal dynamics of their energy spectrum are investigated. It is established that the energy spectrum reveals dependence on the solar activity cycle.

Cosmic ray muonography is a novel technique for imaging of the internal structures of large natural and industrial objects. It exploits the capability of high energy muons from cosmic rays to penetrate large thicknesses of large subjects to be studied, in order to obtain a density map. It uses muon flux attenuation and absorption in materials of investigated objects. Nuclear emulsions are tracking detectors well suited to be employed in muonography for investigations of inner structure of large objects up to kilometers size, since emulsions have firstly an excellent angular resolution, they are compact and robust, do not require power supply. The muonography methods are applied to study one of UNESCO world heritage objects, the unusual building in the Naryn-Kala citadel hidden underground. The use of nuclear emulsions as probing radiation detectors provides for a uniquely high resolution capacity of recording instrumentation combined with the potential of modern image analysis methods giving 3D reconstruction of the internal structures of the investigated object.

The influence of a high-speed solar wind on the state of magnetosphere, as well as on the cosmic ray flux registered on the Earth’s surface by the muon hodoscope URAGAN (MEPhI) is discussed. The results of the analysis of the parameters of muon flux local anisotropy in the periods of low solar activity (2008–2009 and 2017–2018) during geomagnetic disturbances caused by the high-speed solar wind are 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.

In this paper we continue developing an earlier proposed model of quark-gluon blob (QGB) production with large orbital momentum, which allows to demonstrate and study different properties of nucleus-nucleus interactions. In particular, the number of nucleons and transferred energy in QGB are considered and comparison with predictions of other models is analyzed.

A simple, physically validated, model of charge-independence and charge-symmetry breaking is proposed for the pion-nucleon coupling constant. Within this model, the pion-nucleon coupling constants are assumed to be in direct proportion to the masses of nucleons and pions involved in the interaction. The charge dependence of the pion-nucleon coupling constants and low-energy parameters of nucleon-nucleon scattering in the ¹S₀ spin-singlet state is studied on the basis of Yukawa’s meson theory. By using the value of \(f_{pp\pi^0}^2=0.0749(7)\) established reliably for the pseudovector pion-nucleon coupling constant, which characterizes the strength of the nuclear proton-proton interaction, the values of \(f_c^2=0.0802(7)\) and \(f_0^2=0.0750(7)\) were calculated for, respectively, the charged and neutral pion-nucleon coupling constants, along with the value of \(f_{nn\pi^0}^2=0.0751(7)\), which characterizes the strength of the nuclear neutron-neutron interaction. The values calculated for the low-energy parameters of neutron-proton and neutron-neutron scattering with the aid of the above constants agree well with experimental data.