Electron component in primary cosmic rays. II. Theory

The energy spectrum of cosmic-ray electrons can be represented by a power law with a single exponent between 3 and 50 GeV, and a break in the spectrum due to the energy loss of electrons could appear at about 50 GeV or higher. It is necessary to reconcile this high value of the critical energy [Formula: see text] with the effective thickness of matter traversed [Formula: see text] as estimated from the positron flux) and with the small amplitude of anisotropy [Formula: see text]. Hence rather severe conditions are imposed on the properties of the region in which cosmic rays are stored. We have carried out an investigation of the two-component model for storing galactic cosmic rays, which consists of disk and halo components. Assuming the intensity ratio (η) of the halo to the disk components to be nearly unity, one can assign parameters explaining various properties of cosmic rays consistently. For the case of a vanishing halo component (η = 0), the mean scattering length for particle diffusion becomes about 1018 cm.

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Measurement of the cosmic ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite

Science Advances ◽

10.1126/sciadv.aax3793 ◽

2019 ◽

Vol 5 (9) ◽

pp. eaax3793 ◽

Cited By ~ 16

Author(s):

◽

Q. An ◽

R. Asfandiyarov ◽

P. Azzarello ◽

P. Bernardini ◽

...

Keyword(s):

Cosmic Rays ◽

Cosmic Radiation ◽

Precise Measurement ◽

Milky Way ◽

Spectral Feature ◽

Dark Matter Particle ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Proton Spectrum ◽

First Time

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 1/2 years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

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Atmospheric production and transport of 7Be activity by cosmic rays: Modelling with the chemistry-climate model SOCOLv3.0 and comparison with direct measurements

10.5194/egusphere-egu21-2287 ◽

2021 ◽

Author(s):

Kseniia Golubenko ◽

Eugene Rozanov ◽

Genady Kovaltsov ◽

Ari-Pekka Leppänen ◽

Ilya Usoskin

Keyword(s):

Cosmic Rays ◽

Climate Changes ◽

Climate Model ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Cosmogenic Isotopes ◽

Cosmogenic Isotope ◽

The Past ◽

Direct Measurements ◽

First Results

We present the first results of modelling of the short-living cosmogenic isotope 7Be production, deposition, and transport using the chemistry-climate model SOCOLv3.0 aimed to study solar-terrestrial interactions and climate changes. We implemented an interactive deposition scheme, &#160;based on gas tracers with and without nudging to the known meteorological fields. Production of 7Be was modelled using the 3D time-dependent Cosmic Ray induced Atmospheric Cascade (CRAC) model. The simulations were compared with the real concentrations (activity) and depositions measurements of 7Be in the air and water at Finnish stations. We have successfully reproduced and estimated the variability of the cosmogenic isotope 7Be produced by the galactic cosmic rays (GCR) on time scales longer than about a month, for the period of 2002&#8211;2008. The agreement between the modelled and measured data is very good (within 12%) providing a solid validation for the ability of the SOCOL CCM to reliably model production, transport, and deposition of cosmogenic isotopes, which is needed for precise studies of cosmic-ray variability in the past.&#160;

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Particle Acceleration by Supernova Shocks and Spallogenic Nucleosynthesis of Light Elements

Annual Review of Nuclear and Particle Science ◽

10.1146/annurev-nucl-101917-021151 ◽

2018 ◽

Vol 68 (1) ◽

pp. 377-404 ◽

Cited By ~ 12

Author(s):

Vincent Tatischeff ◽

Stefano Gabici

Keyword(s):

Cosmic Rays ◽

Light Element ◽

Cosmic Ray ◽

Nuclear Interaction ◽

Galactic Cosmic Rays ◽

Light Elements ◽

Halo Stars ◽

The Standard Model ◽

Low Metallicity ◽

Galactic Cosmic Ray

In this review, we first reassess the supernova remnant paradigm for the origin of Galactic cosmic rays in the light of recent cosmic-ray data acquired by the Voyager 1 spacecraft. We then describe the theory of light-element nucleosynthesis by nuclear interaction of cosmic rays with the interstellar medium and outline the problem of explaining the measured beryllium abundances in old halo stars of low metallicity with the standard model of the Galactic cosmic-ray origin. We then discuss the various cosmic-ray models proposed in the literature to account for the measured evolution of the light elements in the Milky Way, and point out the difficulties that they all encounter. It seems to us that, among all possibilities, the superbubble model provides the most satisfactory explanation for these observations.

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Short- and Medium-Term Induced Ionization in the Earth Atmosphere by Galactic and Solar Cosmic Rays

International Journal of Atmospheric Sciences ◽

10.1155/2013/184508 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Alexander Mishev

Keyword(s):

Cosmic Rays ◽

Cosmic Ray ◽

Ground Level ◽

Galactic Cosmic Rays ◽

Earth Atmosphere ◽

Medium Term ◽

Ground Level Enhancement ◽

Solar Cosmic Rays ◽

The Earth ◽

Ionization Effect

The galactic cosmic rays are the main source of ionization in the troposphere of the Earth. Solar energetic particles of MeV energies cause an excess of ionization in the atmosphere, specifically over polar caps. The ionization effect during the major ground level enhancement 69 on January 20, 2005 is studied at various time scales. The estimation of ion rate is based on a recent numerical model for cosmic-ray-induced ionization. The ionization effect in the Earth atmosphere is obtained on the basis of solar proton energy spectra, reconstructed from GOES 11 measurements and subsequent full Monte Carlo simulation of cosmic-ray-induced atmospheric cascade. The evolution of atmospheric cascade is performed with CORSIKA 6.990 code using FLUKA 2011 and QGSJET II hadron interaction models. The atmospheric ion rate is explicitly obtained for various latitudes, namely, 40°N, 60°N and 80°N. The time evolution of obtained ion rates is presented. The short- and medium-term ionization effect is compared with the average effect due to galactic cosmic rays. It is demonstrated that ionization effect is significant only in subpolar and polar atmosphere during the major ground level enhancement of January 20, 2005. It is negative in troposphere at midlatitude, because of the accompanying Forbush effect.

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A reevaluation of the atmospheric pressure dependence of secondary cosmic-ray neutrons in the context of Cosmic-Ray Neutron Sensing

10.5194/egusphere-egu21-10602 ◽

2021 ◽

Author(s):

Jannis Weimar ◽

Paul Schattan ◽

Martin Schrön ◽

Markus Köhli ◽

Rebecca Gugerli ◽

...

Keyword(s):

Cosmic Rays ◽

Hydrogen Content ◽

Atmospheric Pressure ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Atmospheric Air ◽

Neutron Intensity ◽

The Earth ◽

Wide Range ◽

Primary Cosmic Rays

Secondary cosmic-ray neutrons may be effectively used as a proxy for environmental hydrogen content at the hectare scale. These neutrons are generated mostly in the upper layers of the atmosphere within particle showers induced by galactic cosmic rays and other secondary particles. Below 15 km altitude their intensity declines as primary cosmic rays become less abundant and the generated neutrons are attenuated by the atmospheric air. At the earth surface, the intensity of secondary cosmic-ray neutrons heavily depends on their attenuation within the atmosphere, i.e. the amount of air the neutrons and their precursors pass through. Local atmospheric pressure measurements present an effective means to account for the varying neutron attenuation potential of the atmospheric air column above the neutron sensor. Pressure variations possess the second largest impact on the above-ground epithermal neutron intensity. Thus, using epithermal neutrons to infer environmental hydrogen content requires precise knowledge on how to correct for atmospheric pressure changes.We conducted several short-term field experiments in saturated environments and at different altitudes, i.e. different pressure states to observe the neutron intensity pressure relation over a wide range of pressure values. Moreover, we used long-term measurements above glaciers in order to monitor the local dependence of neutron intensities and pressure in a pressure range typically found in Cosmic-Ray Neutron Sensing. The results are presented along with a broad Monte Carlo simulation campaign using MCNP 6. In these simulations, primary cosmic rays are released above the earth atmosphere at different cut-off rigidities capturing the whole evolution of cosmic-ray neutrons from generation to attenuation and annihilation. The simulated and experimentally derived pressure relation of cosmic-ray neutrons is compared to those of similar studies and assessed in the light of an appropriate atmospheric pressure correction for Cosmic-Ray Neutron Sensing.

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The Source Composition of Galactic Cosmic Rays as Possibly Originated from the Dust in the Circumstellar and Interstellar Space

International Astronomical Union Colloquium ◽

10.1017/s0252921100067257 ◽

1991 ◽

Vol 126 ◽

pp. 433-436

Author(s):

Kunitomo Sakurai

Keyword(s):

Chemical Composition ◽

Cosmic Rays ◽

Solar Atmosphere ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Interstellar Space ◽

Interstellar Clouds ◽

Supernova Explosions ◽

Siderophile Elements

AbstractThe chemical composition of galactic cosmic rays in their sources is similar to that of interstellar clouds or grains which are relatively enriched in refractory and siderophile elements as compared with the chemical composition of the solar atmosphere. Taking into account this fact, it is shown that the cosmic ray source matter can be identified as the dust or grains observed in the envelopes of red supergiant stars or the matter originally ejected from supernova explosions.

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The Ulysses fast latitude scans: COSPIN/KET results

Annales Geophysicae ◽

10.5194/angeo-21-1275-2003 ◽

2003 ◽

Vol 21 (6) ◽

pp. 1275-1288 ◽

Cited By ~ 8

Author(s):

B. Heber ◽

G. Sarri ◽

G. Wibberenz ◽

C. Paizis ◽

P. Ferrando ◽

...

Keyword(s):

Magnetic Field ◽

Cosmic Rays ◽

Solar Magnetic Field ◽

Solar Maximum ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Solar Particle Events ◽

Interplanetary Magnetic Fields ◽

Solar Particle ◽

Interplanetary Physics

Abstract. Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in December 1997, and its second fast latitude scan in September 2000. In contrast to the first fast latitude scan in 1994/1995, during the second fast latitude scan solar activity was close to maximum. The solar magnetic field reversed its polarity around July 2000. While the first latitude scan mainly gave a snapshot of the spatial distribution of galactic cosmic rays, the second one is dominated by temporal variations. Solar particle increases are observed at all heliographic latitudes, including events that produce >250 MeV protons and 50 MeV electrons. Using observations from the University of Chicago’s instrument on board IMP8 at Earth, we find that most solar particle events are observed at both high and low latitudes, indicating either acceleration of these particles over a broad latitude range or an efficient latitudinal transport. The latter is supported by "quiet time" variations in the MeV electron background, if interpreted as Jovian electrons. No latitudinal gradient was found for >106 MeV galactic cosmic ray protons, during the solar maximum fast latitude scan. The electron to proton ratio remains constant and has practically the same value as in the previous solar maximum. Both results indicate that drift is of minor importance. It was expected that, with the reversal of the solar magnetic field and in the declining phase of the solar cycle, this ratio should increase. This was, however, not observed, probably because the transition to the new magnetic cycle was not completely terminated within the heliosphere, as indicated by the Ulysses magnetic field and solar wind measurements. We argue that the new A<0-solar magnetic modulation epoch will establish itself once both polar coronal holes have developed.Key words. Interplanetary physics (cosmic rays; energetic particles; interplanetary magnetic fields)

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Composition and Galactic Confinement of Cosmic Rays

Highlights of Astronomy ◽

10.1017/s1539299600000873 ◽

1971 ◽

Vol 2 ◽

pp. 740-756

Author(s):

Maurice M. Shapiro

Keyword(s):

Cosmic Rays ◽

Cosmic Ray ◽

High Energy ◽

Galactic Cosmic Rays ◽

Interstellar Space ◽

Heavy Nuclei ◽

High Energy Astrophysics ◽

Transit Times ◽

The Galaxy ◽

Path Lengths

The ‘Galactic’ cosmic rays impinging on the Earth come from afar over tortuous paths, traveling for millions of years. These particles are the only known samples of matter that reach us from regions of space beyond the solar system. Their chemical and isotopic composition and their energy spectra provide clues to the nature of cosmic-ray sources, the properties of interstellar space, and the dynamics of the Galaxy. Various processes in high-energy astrophysics could be illuminated by a more complete understanding of the arriving cosmic rays, including the electrons and gamma rays.En route, some of theprimordialcosmic-ray nuclei have been transformed by collision with interstellar matter, and the composition is substantially modified by these collisions. A dramatic consequence of the transformations is the presence in the arriving ‘beam’ of considerable fluxes of purely secondary elements (Li, Be, B), i.e., species that are, in all probability, essentially absent at the sources. We shall here discuss mainly the composition of the arriving ‘heavy’ nuclei -those heavier than helium - and what they teach us about thesourcecomposition, the galactic confinement of the particles, their path lengths, and their transit times.

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Cosmic ray spectra in planetary atmospheres

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309029718 ◽

2008 ◽

Vol 4 (S257) ◽

pp. 471-473

Author(s):

M. Buchvarova ◽

P. Velinov

Keyword(s):

Experimental Data ◽

Solar Cycle ◽

Cosmic Rays ◽

Cosmic Ray ◽

Planetary Atmospheres ◽

Galactic Cosmic Rays ◽

Outer Planets ◽

Practical Possibility ◽

The Earth ◽

Theoretical Results

AbstractOur model generalizes the differential D(E) and integral D(>E) spectra of cosmic rays (CR) during the 11-year solar cycle. The empirical model takes into account galactic (GCR) and anomalous cosmic rays (ACR) heliospheric modulation by four coefficients. The calculated integral spectra in the outer planets are on the basis of mean gradients: for GCR – 3%/AU and 7%/AU for anomalous protons. The obtained integral proton spectra are compared with experimental data, the CRÈME96 model for the Earth and theoretical results of 2D stochastic model. The proposed analytical model gives practical possibility for investigation of experimental data from measurements of galactic cosmic rays and their anomalous component.

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Effects of solar activity and galactic cosmic ray cycles on the modulation of the annual average temperature at two sites in southern Brazil

Annales Geophysicae ◽

10.5194/angeo-36-555-2018 ◽

2018 ◽

Vol 36 (2) ◽

pp. 555-564 ◽

Cited By ~ 4

Author(s):

Everton Frigo ◽

Francesco Antonelli ◽

Djeniffer S. S. da Silva ◽

Pedro C. M. Lima ◽

Igor I. G. Pacca ◽

...

Keyword(s):

Solar Activity ◽

Cosmic Rays ◽

Cosmic Ray ◽

Galactic Cosmic Rays ◽

Southern Brazil ◽

Solar Cycles ◽

Annual Average ◽

Average Temperature ◽

Weather Stations ◽

Annual Average Temperature

Abstract. Quasi-periodic variations in solar activity and galactic cosmic rays (GCRs) on decadal and bidecadal timescales have been suggested as a climate forcing mechanism for many regions on Earth. One of these regions is southern Brazil, where the lowest values during the last century were observed for the total geomagnetic field intensity at the Earth's surface. These low values are due to the passage of the center of the South Atlantic Magnetic Anomaly (SAMA), which crosses the Brazilian territory from east to west following a latitude of ∼ 26∘. In areas with low geomagnetic intensity, such as the SAMA, the incidence of GCRs is increased. Consequently, possible climatic effects related to the GCRs tend to be maximized in this region. In this work, we investigate the relationship between the ∼ 11-year and ∼ 22-year cycles that are related to solar activity and GCRs and the annual average temperature recorded between 1936 and 2014 at two weather stations, both located near a latitude of 26∘ S but at different longitudes. The first of these stations (Torres – TOR) is located in the coastal region, and the other (Iraí – IRA) is located in the interior, around 450 km from the Atlantic Ocean. Sunspot data and the solar modulation potential for cosmic rays were used as proxies for the solar activity and the GCRs, respectively. Our investigation of the influence of decadal and bidecadal cycles in temperature data was carried out using the wavelet transform coherence (WTC) spectrum. The results indicate that periodicities of 11 years may have continuously modulated the climate at TOR via a nonlinear mechanism, while at IRA, the effects of this 11-year modulation period were intermittent. Four temperature maxima, separated by around 20 years, were detected in the same years at both weather stations. These temperature maxima are almost coincident with the maxima of the odd solar cycles. Furthermore, these maxima occur after transitions from even to odd solar cycles, that is, after some years of intense GCR flux. The obtained results offer indirect mathematical evidence that solar activity and GCR variations contributed to climatic changes in southern Brazil during the last century. A comparison of the results obtained for the two weather stations indicates that the SAMA also contributes indirectly to these temperature variations. The contribution of other mechanisms also related to solar activity cannot be excluded. Keywords. Meteorology and atmospheric dynamics (climatology)

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