Origin of hardening in spectra of cosmic ray nuclei at a few hundred GeV using AMS-02 data

Many experiments have confirmed spectral hardening at a few hundred GeV in the spectra of cosmic ray(CR)nuclei.Three different origins have been proposed:primary source acceleration,propagation,and the superposition of different kinds of sources.In this work,a broken power law has been employed to fit each of the spectra of cosmic ray nuclei from AMS-02 directly,for rigidities greater than 45 GeV.The fitting results of the break rigidity and the spectral index differences less than and greater than the break rigidity show complicated relationships among different nuclear species,which cannot be reproduced naturally by a simple primary source scenario or a propagation scenario.However,with a natural and simple assumption,the superposition of different kinds of sources could have the potential to explain the fitting results successfully.Spectra of CR nuclei from a single future experiment,such as DAMPE,will provide us the opportunity to do cross checks and reveal the properties of the different kinds of sources.     

Spatial dependent diffusion of cosmic rays and the excess of primary electrons derived from high precision measurements by AMS-02

The precise spectra of Cosmic Ray(CR) electrons and positrons have been published by the measurement of AMS-02. It is reasonable to regard the difference between the electron and positron spectra(?Φ = Φ_(e-)-Φ_(e+)) as being dominated by primary electrons. The resulting electron spectrum shows no sign of spectral softening above 20 GeV, which is in contrast with the prediction of the standard model of CR propagation. In this work, we generalize the analytic one-dimensional two-halo model of diffusion to a three-dimensional realistic calculation by implementing spatial variant diffusion coefficients in the DRAGON package. As a result, we can reproduce the spectral hardening of protons observed by several experiments, and predict an excess of high energy primary electrons which agrees with the measurement reasonably well. Unlike the break spectrum obtained for protons, the model calculation predicts a smooth electron excess and thus slightly over-predicts the flux from tens of GeV to 100 GeV. To understand this issue, further experimental and theoretical studies are necessary.     

Galactic cosmic ray propagation: sub-PeV diffuse gamma-ray and neutrino emission

The Tibet ASγ experiment just reported their measurement of sub-PeV diffuse gamma-ray emission from the Galactic disk, with the highest energy up to 957 TeV. These diffuse gamma rays are most likely the hadronic origin by cosmic ray (CR) interaction with interstellar gas in the galaxy. This measurement provides direct evidence to the hypothesis that the Galactic Cosmic Rays (GCRs) can be accelerated beyond PeV energies. In this work, we try to explain the sub-PeV diffuse gamma-ray spectrum with different CR propagation models. We find that there is a tension between the sub-PeV diffuse gamma-ray and the local CR spectrum. To describe the sub-PeV diffuse gamma-ray flux, it generally requires larger local CR flux than measurement in the knee region. We further calculate the PeV neutrino flux from the CR propagation model. Even all of these sub-PeV diffuse gamma rays originate from the propagation, the Galactic Neutrinos (GNs) only account for less than ~15% of observed flux, most of which are still from extragalactic sources.     

Galactic cosmic ray propagation: sub-PeV diffuse gamma-ray and neutrino emission

The Tibet ASγ experiment just reported their measurement of sub-PeV diffuse gamma-ray emission from the Galactic disk, with the highest energy up to 957 TeV. These diffuse gamma rays are most likely the hadronic origin by cosmic ray (CR) interaction with interstellar gas in the galaxy. This measurement provides direct evidence to the hypothesis that the Galactic Cosmic Rays (GCRs) can be accelerated beyond PeV energies. In this work, we try to explain the sub-PeV diffuse gamma-ray spectrum with different CR propagation models. We find that there is a tension between the sub-PeV diffuse gamma-ray and the local CR spectrum. To describe the sub-PeV diffuse gamma-ray flux, it generally requires larger local CR flux than measurement in the knee region. We further calculate the PeV neutrino flux from the CR propagation model. Even all of these sub-PeV diffuse gamma rays originate from the propagation, the Galactic Neutrinos (GNs) only account for less than ~15% of observed flux, most of which are still from extragalactic sources.     

Theoretical considerations on the extraction of pp cross sections from cosmic ray absorption data

It has been suggested, based on the application of Glauber theory to proton-air collisions, that a proton-proton total cross section which rises with energy as 1n²s is consistent with cosmic ray data. We show that if instead of a constant width, one uses a pp diffractive width which decreases consistent with present data, the cosmic ray data continue to rule out constant σ_pp^T. However, the size of the derived pp cross section is somewhat sensitive to the width, and in the relevant energy range 15% uncertainty in σ_pp^T is the maximum consequence of uncertainties in the width. Repetition of these experiments on different nuclei is not a particularly useful way to resolve these width-dependent effects.     

Effect of long-term variability of galactic cosmic ray fluxes on climatic parameters

Using of 200-year variations in solar activity and geomagnetic dipole changes in the time interval to 100000 years ago it is shown geophysical parameters effectively influence climate change. This effect is realized through modulation of the intensity of galactic cosmic ray fluxes penetrating the atmosphere.     

Review of the results of measurements of the fluxes of the charged components of galactic cosmic rays in the experiments PAMELA and AMS-02

The paper provides a review of the results of precision measurements of the fluxes of different charged components of galactic cosmic rays (positrons and antiprotons, protons and helium nuclei) in modern experiments with magnetic spectrometers PAMELA and AMS-02, operating successfully for a few years (since 2006 and 2011, respectively) in Earth orbit. A priority of the PAMELA spectrometer scientific discoveries is noted. It is also noted that the measurements from the AMS-02 experiment are of high statistical accuracy and have reliably confirmed previous data, having been able to advance to a higher energy range.     

阿尔法磁谱仪配电系统的热控系统设计及实验研究

本文以阿尔法磁谱仪中的配电系统为研究对象,阐述了利用热管解决配电系统局部温度过高的热控问题。通过数值模拟,采用体点散热问题的仿生优化方法,获得了高导热性的热管在母板中的人工构造,构建了一种有效的热控系统。数值模拟和实验结果对比验证了数值模拟模型的可靠性和仿生优化方法的可行性,也说明了热管在均温和传热方面的优良作用。     

Bremsstrahlung photons from cosmic ray muons of high and ultrahigh energies

The results from calculations for fluxes of bremsstrahlung photons generated at different depths in the atmosphere by cosmic ray muons with energies of up to 10¹⁰ GeV are presented. It is shown that the generation of charmed particles in the atmosphere, along with the generation of J/ψ mesons, must be taken into account in interpretations of experimental data on studying EASes at high and ultrahigh energies.     

Model calculations of the particle spectrum of the galactic cosmic ray (GCR) environment: Assessment with ACE/CRIS and MARIE measurements

For a given galactic cosmic ray (GCR) environment, understanding the distribution of the particle flux (protons, alpha particles, and heavy ions) in deep-space and on the surface of planetary systems such as Mars are essential for the risk assessment of future human exploration missions. In our model calculations, we make use of the NASA's HZETRN (High Z and Energy Transport) code along with the nuclear fragmentation cross sections that are described by the quantum multiple scattering (QMSFRG) model with the time-dependant variation of the GCR environment derived making use of the solar modulation potential, phi. Data from the cosmic ray isotope spectrometer (CRIS) instrument onboard the advanced composition explorer (ACE) has been available from 1998. Data from the CRIS instrument is being analyzed to understand the short term variations in the particle spectrum during the current solar cycle phase. In this report, particle spectrum for December 2002 of the CRIS instrument was compared with the model calculations. Current assessment of the model calculations show very good agreement of the particle flux (15% for low Z and 5% for high Z) data from Boron (Z=5) through Nickel (Z=28) nuclei for the energy bins reported by CRIS. Similarly, the model calculated dose–rate calculations are compared with the proton flux measured dose–rate from the Martian Radiation Environment Experiment (MARIE) currently onboard the 2001 Mars Odyssey spacecraft in Martian orbit for the month of August 2003 that is representative of a quiet-time GCR data at Mars. Current model calculations are well within 10% of the measured observations of MARIE. The predictive capabilities of the quiet-time GCR particle flux model calculations are promising for biological and shielding studies and for the radiation risk assessment for future human explorations.     

Ultra-high energy cosmic rays and prompt TeV gamma rays from gamma ray bursts

Gamma ray bursts (GRBs) have been proposed as one possible class of sources of the ultrahigh energy cosmic ray (UHECR) events observed up to energies ≳ 10²⁰ eV. The synchrotron radiation of the highest energy protons accelerated within the GRB source should produce gamma rays up to TeV energies. Here we briefly discuss the implications on the energetics of the GRB from the point of view of the detectability of the prompt TeV γ-rays of proton-synchrotron origin in GRBs in the up-coming ICECUBE muon detector in the south pole.     

Analysis of cosmic ray data on nucleon-nucleus collisions and its implication on high energy behaviour of nucleon-nucleon total cross section

From existing cosmic ray measurements of theinelastic collision cross sections of nucleons on nuclei of carbon, iron and lead in the range of energies 10² to 10⁴ GeV as well as the measurements of cross sections on air nuclei in the extensive air shower (EAS) regions (10⁵ to 10⁸ GeV), we conclude that the Glauber multiple scattering theory is adequate to account for the data. Recent suggestion of Maor and Nussinov to parametrize the nucleon-nucleon total cross section with a component growing proportional to ln² E (E is the incident energy) is at variance with the EAS data. However the data are consistent with a nucleon-nucleon total cross section rising no faster than lnE in these energy regions.     

The TeV-scale cosmic ray proton and helium spectra: Contributions from the local sources

Recent measurements of cosmic ray proton and helium spectra show a hardening above a few hundreds of GeV. This excess is hard to understand in the framework of the conventional models of galactic cosmic ray production and propagation. Here, we propose to explain this anomaly by the presence of local sources. Cosmic ray propagation is described as a diffusion process taking place inside a two-zone magnetic halo. We calculate the proton and helium fluxes at the Earth between 50 GeV and 100 TeV. Improving over a similar analysis, we consistently derive these fluxes by taking into account both local and remote sources for which a unique injection rate is assumed. We find cosmic ray propagation parameters for which the proton and helium spectra remarkably agree with the PAMELA and CREAM measurements over four decades in energy.     

The GZK horizon and constraints on the cosmic ray source spectrum from observations in the GZK regime

We discuss the GZK horizon of protons and present a method to constrain the injection spectrum of ultrahigh energy cosmic rays (UHECRs) from supposedly identified extragalactic sources. This method can be applied even when only one or two events per source are observed and is based on the analysis of the probability for a given source to populate different energy bins, depending on the actual cosmic ray injection spectral index. In particular, we show that for a typical source density of 4 × 10⁻⁵ Mpc⁻³, a data set of 100 events above 6 × 10¹⁹ eV allows one in 97% of all cases to distinguish a source spectrum dN/dE ∝ E ^−1.1 from one with E ^–2.7 at 95% confidence level. The article is published in the original.     

The GZK horizon and constraints on the cosmic ray source spectrum from observations in the GZK regime

JETP Letters - We discuss the GZK horizon of protons and present a method to constrain the injection spectrum of ultrahigh energy cosmic rays (UHECRs) from supposedly identified extragalactic...     

BESS data on primary cosmic rays and muons

We have measured absolute fluxes of primary protons, helium nuclei and atmospheric muons with the BESS spectrometer. Precise measurement of these cosmic-ray particles is indispensable for improving the accuracy in the atmospheric neutrino calculations.     

Ultra high energy neutrino–nucleon cross section from cosmic ray experiments and neutrino telescopes

We deduce the cosmogenic neutrino flux by jointly analysing ultra high energy cosmic ray data from HiRes-I and II, AGASA and the Pierre Auger Observatory. We make two determinations of the neutrino flux by using a model-dependent method and a model-independent method. The former is well-known, and involves the use of a power-law injection spectrum. The latter is a regularized unfolding procedure. We then use neutrino flux bounds obtained by the RICE experiment to constrain the neutrino–nucleon inelastic cross section at energies inaccessible at colliders. The cross section bounds obtained using the cosmogenic fluxes derived by unfolding are the most model-independent bounds to date.     

A study on the sharp knee and fine structures of cosmic ray spectra

The paper investigates the overall and detailed features of cosmic ray(CR) spectra in the knee region using the scenario of nuclei-photon interactions around the acceleration sources.Young supernova remnants can be the physical realities of such kind of CR acceleration sites.The results show that the model can well explain the following problems simultaneously with one set of source parameters:the knee of CR spectra and the sharpness of the knee,the detailed irregular structures of CR spectra,the so-calledc...