Nuclear Component Of Cosmic Rays Research Articles

Cross sections for 68Ge production in natural- and enriched-germanium targets irradiated with protons of energy 100 MeV and background in experiments devoted to searches for the 2β0ν decay of 76Ge

The rate of 68Ge production at sea level under the effect of the nuclear component of cosmic rays is calculated. The calculation is based on the experimental values of the cross sections for 68Ge production in natural- and enriched-germanium targets (enrichment in 76Ge) irradiated with high-energy protons. The background from the decays of 68Ge can be a serious problem in new-generation experiments devoted to searches for the 2β0ν decay of 76Ge.

Identification of the light nuclei component of cosmic rays with the PAMELA experiment

The PAMELA (Payload for Antimatter Matter Exploration and Light nuclei Astrophysics) experiment is a satellite-borne apparatus that will make long duration measurements of the cosmic radiation with a particular focus on antiparticles and light nuclei. The main scientific objective of the PAMELA mission is to investigate the nature of the dark matter that pervades the universe, the apparent absence of cosmological antimatter, the origin and evolution of matter in the Galaxy. Specifically PAMELA will measure the cosmic-ray antiproton and positron spectra over the largest energy range ever achieved and will search for antinuclei with unprecedented sensitivity. Furthermore, it will measure the light nuclear component of cosmic rays from Hydrogen up to Oxygen in the interval 200 MeV/ n–150 GeV/ n. Accurate measurements of the elemental composition are required in order to understand the origin, propagation and lifetime of the cosmic radiation. The primary cosmic rays (e.g. C, N and O), produced at the sources, propagate through the interstellar medium giving information about the composition at the source. Secondary elements (e.g. Li, Be, and B) are tracers of amount of matter traversed by the cosmic rays. The relative abundances of the constituents of galactic cosmic rays provide information about cosmic-ray transport within the Galaxy. PAMELA consists of a magnetic spectrometer, a Time-of-Flight and trigger system, an electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. The combination of these devices allows antiparticles to be reliably identified from a large background of other charged particles. This paper reviews the capability of the PAMELA subdetectors to identify light nuclei. Analysis techniques to discriminate light-charged particles will be presented.

A technique for identifying nuclei in the MONICA experiment

We discuss the results of comparison and optimization of (ΔE − E) methods for identifying nuclei with the aid of a multilayer Si detector that will be used in the MONICA satellite-based experiment aimed at studying the nuclear component of cosmic rays from hydrogen to nickel in the energy range of 10–300 MeV/nucleon. The residual-range and Bethe-Bloch curve approximation methods are considered. Using the GEANT4 simulation, it is shown that the Bethe-Bloch curve approximation method not only ensures a better mass resolution (which is particularly important for identification of heavy nuclei), but also provides a means for identifying “drift” nuclei with satisfactory charge (<0.3) and energy (<3%) resolutions. The results can be used to prepare new experiments in which (ΔE − E) nuclear identification methods are expected to be employed.

PAMELA mission: Constraints to cosmic rays propagation from nuclei

The PAMELA (Payload for Antimatter Matter Exploration and Light nuclei Astrophysics) experiment is a satellite-borne apparatus that performes measurements of the cosmic radiation with a particular focus on antiparticles and light nuclei. Accurate measurements of the elemental composition of cosmic rays are required in order to understand the origin, propagation and lifetime of the cosmic radiation. In particular PAMELA measures the light nuclear component of cosmic rays from Hydrogen up to Oxygen in the interval 200 MeV/n-200 GeV/n. Object of this paper is the presentation of light-charge identification capabilities of PAMELA instrument as evaluated during the first three years of flight.

Magnetospheric and solar physics observations with the PAMELA experiment

PAMELA is a satellite-borne experiment designed to make long duration measurements of the cosmic radiation in Low Earth Orbit. It is devoted to the detection of the cosmic-ray spectra in the 100MeV–300GeV range with primary scientific goal the measurement of antiproton and positron spectra over the largest energy range ever achieved. Other tasks include the search for antinuclei with unprecedented sensitivity and the measurement of the light nuclear component of cosmic rays. In addition, PAMELA can investigate phenomena connected with solar and Earth physics. The apparatus consists of: a Time of Flight system, a magnetic spectrometer, an electromagnetic imaging calorimeter, a shower tail catcher scintillator, a neutron detector and an anticoincidence system. In this work we present some measurements of galactic, secondary and trapped particles performed in the first months of operation.

PAMELA observational capabilities of Jovian electrons

PAMELA is a satellite-borne experiment that has been launched on June 15th, 2006. It is designed to make long duration measurements of cosmic radiation over an extended energy range. Specifically, PAMELA is able to measure the cosmic ray antiproton and positron spectra over the largest energy range ever achieved and will search for antinuclei with unprecedented sensitivity. Furthermore, it will measure the light nuclear component of cosmic rays and investigate phenomena connected with solar and earth physics. The apparatus consists of: a time of flight system, a magnetic spectrometer, an electromagnetic imaging calorimeter, a shower tail catcher scintillator, a neutron detector and an anticoincidence system. In this work a study of the PAMELA capabilities to detect electrons is presented. The Jovian magnetosphere is a powerful accelerator of electrons up to several tens of MeV as observed at first by Pioneer 10 spacecraft (1973). The propagation of Jovian electrons to Earth is affected by modulation due to Corotating Interaction Regions (CIR). Their flux at Earth is, moreover, modulated because every ∼13 months Earth and Jupiter are aligned along the average direction of the Parker spiral of the Interplanetary Magnetic Field. PAMELA will be able to measure the high energy tail of the Jovian electrons in the energy range from 50 up to 130 MeV. Moreover, it will be possible to extract the Jovian component reaccelerated at the solar wind termination shock (above 130 MeV up to 2 GeV) from the galactic flux.

Spectrum of Cosmic Rays Produced in Supernova Remnants

Nonlinear kinetic theory of cosmic-ray (CR) acceleration in supernova remnants is employed to calculate CR spectra. The magnetic field in SNRs is assumed to be significantly amplified by the efficiently accelerating nuclear CR component. It is shown that the calculated CR spectra agree in a satisfactory way with the existing measurements up to the energy 1017 eV. The power-law spectrum of protons extends up to the energy 3 × 1015 eV with a subsequent exponential cutoff. It gives a natural explanation for the observed knee in the Galactic CR spectrum. The maximum energy of the accelerated nuclei is proportional to their charge number Z. Therefore, the break in the Galactic CR spectrum is the result of the contribution of progressively heavier species in the overall CR spectrum so that at 1017 eV the CR spectrum is dominated by iron group nuclei. It is shown that this component plus a suitably chosen extragalactic CR component can give a consistent description for the entire Galactic CR spectrum.

A new method for determining particle energy in the range 1011?1015 eV and results from a beam test at 180 GeV/c

A method for measuring the energy of the nuclear component of cosmic rays is described. The principle of the method consists in determining the energy of a primary nucleus from the space density of secondary particles produced in a thin target in the initial event of inelastic interaction. The results from testing the method on an ejected 180-GeV pion beam are presented. Analysis of the experimental data and simulation show that, using this method, it is possible to measure the particle energy with a relative error of ∼67%. The method is being developed for the direct detection of cosmic rays over wide ranges of energy (1011−1015 eV/particle) and charge (Z = 1–30) during a cosmic experiment in near-Earth space.

Gamma-ray astronomy and cosmic ray origin problem

We analyse the results of the nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) in order to describe their relevant properties: the remnant dynamics and the characteristics of nonthermal emission produced by CRs. It is shown that the theory fits the existing data in a satisfactory way and that the magnetic field in SNRs is significantly amplified due to efficient acceleration of the nuclear CR component. From the fact that magnetic field amplification occurs in all the young SNRs for which relevant data exist, and given the strong theoretical connection between magnetic field amplification and efficiently accelerating the nuclear CRs, we tentatively conclude that the Galactic SNRs are the source population of the Galactic CRs. Due to high interior magnetic fields in young SNRs the π 0-decay γ-rays generated by the nuclear CR component as a rule dominate over γ-rays generated by the electron CR component, and the calculated γ-ray flux fits existing data.

The theory of synchrotron emission from supernova remnants

The time-dependent nonlinear kinetic theory for cosmic ray (CR) acceleration in supernova remnants (SNRs) is ap- plied studying the properties of the synchrotron emission from SNRs, in particular, the surface brightness-diameter (Σ − D )r e- lation. Detailed numerical calculations are performed for the expected range of the relevant physical parameters, namely the ambient density and the supernova explosion energy. The magnetic field in SNRs is assumed to be significantly amplified by the efficiently accelerating nuclear CR component. Due to the growing number of accelerated CRs the expected SNR luminosity increases during the free expansion phase, reaches a peak value at the beginning of the Sedov phase and then decreases again, since in this stage the overall CR number remains nearly constant, whereas the effective magnetic field diminishes with time. The theoretically predicted brightness-diameter relation in the radio range in the Sedov phase is close to ΣR ∝ D −17/4 . It fits the observational data in a very satisfactory way. The observed spread of ΣR at a given SNR size D is the result of the spread of supernova explosion energies and interstellar medium densities.

The Space Experiment PAMELA

We present in this paper a status report of the space experiment PAMELA. PAMELA is a satellite-borne experiment which primarily aims to measure the antiproton and positron spectra in the cosmic radiation over a large energy range (from 80 MeV up to 190 GeV for antiprotons and from 50 MeV up to 270 GeV for positrons) and to search for antinuclei with a sensitivity of the order of 10 −8 in the antihelium/helium ratio. In addition, it will measure the light nuclear component of cosmic rays and investigate phenomena connected with Solar and Earth physics. The apparatus will be installed onboard the polar orbiting Resurs DK1 satellite, which will be launched into space by a Soyuz TM2 rocket in 2004 from Baikonur cosmodrome in Kazakhstan, for a 3 year long mission. PAMELA consists of: a time of flight system, a transition radiation detector, a magnetic spectrometer, an anticoincidence detector, an electromagnetic imaging calorimeter, a shower tail catcher scintillator and a neutron detector.

Direct evidence of efficient cosmic ray acceleration and magnetic field amplification in Cassiopeia A

It is shown that the nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) describes the shell-type nonthermal X-ray morphology of Cas A, obtained in Chandra observations, in a satisfactory way. The set of empirical parameters, like distance, source size and total energy release, is the same which reproduces the dynamical properties of the SNR and the spectral characteristics of the emission produced by CRs. The extremely small spatial scales in the observed morphological structures at hard X-ray energies are due to a large effective magnetic field B d ∼ 500 μG in the interior which is at the same time not only required but also sufficient to achieve the excellent agreement between the spatially integrated radio and X-ray synchrotron spectra and their calculated form. The only reasonably thinkable condition for the production of such a large effective field strength is a very efficiently accelerated nuclear CR component. Therefore the Chandra data confirm first of all the inference that Cas A indeed accelerates nuclear CRs with the high efficiency required for Cas A to be considered as a member of the main class of Galactic CR sources and, secondly, that the nonlinear kinetic theory of CR acceleration in SNRs is a reliable method to determine the magnetic field value in SNRs.

Confirmation of strong magnetic field amplification and nuclear cosmic ray acceleration in SN 1006

It is shown that the nonlinear kinetic model of cosmic ray (CR) acceleration in supernova remnants (SNRs) fits the shell-type nonthermal X-ray morphology, obtained in Chandra observations, in a satisfactory way. The set of empirical parameters is the same which reproduces the dynamical properties of the SNR and the spectral characteristics of the emission produced by CRs. The extremely small spatial scales of the observed X-ray distribution are due to the large effective magnetic field $B_{\mathrm d}\sim 100$ $\mu$G in the interior, which is also required to give a good fit for the spatially integrated radio and X-ray synchrotron spectra. The only reasonably thinkable condition for the production of such a large effective field strength is an efficiently accelerated nuclear CR component. Therefore the Chandra data confirm the inference that SN 1006 indeed accelerates nuclear CRs with the high efficiency required for SNRs to be considered as the main Galactic CR sources.

Emission of SN 1006 produced by accelerated cosmic rays

The nonlinear kinetic model of cosmic ray (CR) acceleration in supernova remnants (SNRs) is used to describe the properties of the remnant of SN 1006. It is shown, that the theory fits the existing data in a satisfactory way within a set of parameters which is consistent with the idea that SN 1006 is a typical source of Galactic CR nucleons, although not necessarily of CR electrons. The adjusted parameters are those that are not very well determined by present theory or not directly amenable to astronomical observations. The calculated expansion law and the radio-, X-ray and-ray emissions produced by the accelerated CRs in SN 1006 agree quite well with the observations. A rather large interior magnetic field Bd 100G is required to give a good fit for the radio and X-ray synchrotron emission. In the predicted TeV-ray flux from SN 1006, the 0 -decay -rays, generated by the nuclear CR component, dominate over the inverse Compton (IC) -rays, generated by the CR electrons in the cosmic microwave background. The predicted source morphology in high energy-rays roughly corresponds to that of the synchrotron emission. The predicted integral-ray flux F / 1 extends up to energies100 TeV if CR diusion is as strong as the Bohm limit. Only if the interior magnetic field is much lower in the SNR, Bd 10G, then the observed-ray emission can be due to the accelerated electron component alone. In this case, not plausible physically in our view, the lowest permissible value of the electron to proton ratio is rather high, and the maximum individual energy and total energy content of accelerated nucleons so small, that SN 1006 can not be considered as a typical source of the nuclear Galactic CRs.

Particle acceleration in active galactic nuclei

Multifrequency observations of Active Galactic Nuclei (AGN) from radio to the X-ray band have now provided evidence that they are site of production of high temperature plasmas (kT > 100 MeV) with strong tails of suprathermal particles. This hot phase is necessarily mixed with a distribution of dense, cold clouds, which scatter, absorb and reprocess the radiation from the hot plasma and relativistic particles, and contribute to form the observed spectra. The generation of high temperature, relativistic plasmas and suprathermal particles is a very challenging problem, not only in the framework of the study of AGN as such, but also in the more general context of the origin of high-energy cosmic rays. In this review we discuss the physical processes which have been suggested to operate in AGN, with special attention for the aspects connected with the generation of specific and/or bulk relativistic energies. Extended radio sources are discussed in these Proceedings by dr. Scheuer as a typical environment where ultra-high-energy cosmic rays (UHECR) may be produced, either by mechanisms based on ordered fields or by stochastic acceleration processes. AGN, which are often associated with them, might appear to be an even better source of high energy particles because of their compactness and global energetics. However they are characterized by high photon densities; correspondingly photomeson losses reduce the final specific energies of the particles allowed to escape. In this sense we may conclude that AGN deliver large amounts of energy into the surrounding components (for instance the extended radio lobes), but are not likely to be the prime generators of the nuclear component of cosmic rays above 10 18 eV. Conversely the neutrino component might be an important product of compact galactic cores and, as such, would represent in perspective a method for investigating AGN. We conclude with some remarks about the possibility of further accelerating energetic particles emerging from AGN in the large scale structures of the local Supercluster, as a viable alternative to explain the generation of extragalactic UHECR.

The diffusion model of cosmic-ray propagation

We set up diffusion equations for the nuclear component of cosmic rays and solve these to find the ratio of light to medium nuclei in the cosmic rays as well as the gamma-ray distribution in our Galaxy. From a comparison of our calculated quantities with observational data we determine the values of various parameters appearing in the model. We find that best agreement between theory and observations is obtained if the cosmic-ray confinement region consists of a narrow disk of total height 160 pc and radius 16 kpc, where the cosmic-ray sources are located, and an extensive halo of height 20 kpc. The diffusion coefficient near the Sun must be between 1026 and 1027 cm2 s−1 while it equals 1028 to 1029 cm2 s−1 in the halo. Finally, we find that the diffusion coefficient in the Galaxy must depend on the gas density as a power law with an index of the order of −1.

SOVIET SATELLITE AND ROCKET INVESTIGATIONS OF THE NUCLEAR COMPONENT OF COSMIC RAYS

Introduction 230 I. Investigation of the Nuclear Component of Cosmic Rays with Soviet Satellites and Space Rockets 230 1. Procedure 231 2. Chemical Composition of Cosmic Rays. Fluxes of Nuclei of Different Groups and Their Energy Spectra 234 3. Variations of the Flux of the Nuclear Component of Cosmic Rays and Nuclei of Solar Origin 249 II. Use of Artificial Satellites and Rockets to Investigate the Primary Cosmic Radiation 260 4. Nuclear Component of Galactic Cosmic Rays 260 5. Solar Cosmic Rays and High-latitude Cutoff 262 6. Electron-positron Cosmic-ray Component 263 Literature 266

Исследования ядерной компоненты космических лучей, проведенные на советских спутниках и ракетах

Исследования ядерной компоненты космических лучей, проведенные на советских спутниках и ракетах

Study of nuclear component of cosmic rays in third space vehicle

Study of nuclear component of cosmic rays in third space vehicle

Apparatus for investigating the nuclear component of cosmic rays in cosmic rockets and artificial earth satellites: G. S. Dragun, L. V. Kurnosova, V. T. Logachev, L. A. Razorenov, I. A. Sirotkin and M. I. Fradkin(pp. 86–110)

Apparatus for investigating the nuclear component of cosmic rays in cosmic rockets and artificial earth satellites: G. S. Dragun, L. V. Kurnosova, V. T. Logachev, L. A. Razorenov, I. A. Sirotkin and M. I. Fradkin(pp. 86–110)