New measurements of charge-changing cross sections in carbon and hydrogen targets above 2 GeV per nucleon: Evidence for an energy dependence that may strongly affect estimates of the energy dependence of cosmic-ray diffusion in the galaxy

1994 ◽  
Vol 429 ◽  
pp. 764 ◽  
Author(s):  
W. R. Webber ◽  
W. R. Binns ◽  
D. Crary ◽  
M. Westphall
Keyword(s):  
Energy Dependence ◽  
Cross Sections ◽  
Cosmic Ray ◽  
The Galaxy ◽  
Ray Diffusion

Cosmic-ray nuclei up to 10 10 eV/u in the galaxy

1975 ◽  
Vol 277 (1270) ◽  
pp. 319-348 ◽  
Keyword(s):  
Cosmic Rays ◽  
Solar System ◽  
Cross Sections ◽  
Cosmic Ray ◽  
Interstellar Space ◽  
Heavy Nuclei ◽  
Hydrogen Atoms ◽  
Interstellar Gas ◽  
The Galaxy ◽  
Ionization Cross Sections

O f the nuclear cosmic rays arriving in the vicinity of Earth from interstellar space, more than 90% have energies less than 1010 eV /u.f Some effects of their modulation (including deceleration) in the Solar System are briefly discussed. The origin of particles at energies < 107 eV/u is still obscure. They could be due to stellar explosions or to solar emissions, or perhaps to interaction of interstellar gas with the solar wind. Between 108 and 1010 eV/u, the composition appears constant to ca. 30% within the statistics of available data. Cosmic rays traverse a mean path length of 6 g/cm 2 in a medium assumed to contain nine hydrogen atoms for each helium atom. Spallation reactions occurring in this medium result in enhancement of many cosmic-ray elements that are more scarce in the general abundances by several orders of magnitude. Cosmic-ray dwell time in the Galaxy seems to be < 107 years. The source composition of cosmic rays has been derived for elements with atomic numbers 1 ≤ Z ≤ 26. A comparison with abundances in the Solar System implies that the latter is richer in hydrogen and helium by a factor of ca. 20, in N and O by ca. 5, and in C by a factor of ca.2. Possible interpretations invoke (a) nucleosynthesis of cosmic rays in certain sources, e.g. supernovae, or (b) models of selective injection that depend, e.g. on ionization potentials or ionization cross sections. Calculated isotopic abundances of arriving cosmic rays are compared with the observed values now becoming available, and found to be in general agreement. Recent progress in probing the composition and spectrum of ultra-heavy nuclei is outlined.

Considerations affecting the estimation of cosmic-ray age

1968 ◽  
Vol 46 (10) ◽  
pp. S561-S568 ◽  
Author(s):  
M. M. Shapiro ◽  
R. Silberberg
Keyword(s):  
Cosmic Rays ◽  
Cross Sections ◽  
Galactic Disk ◽  
Principal Component ◽  
Cosmic Ray ◽  
Light Nuclei ◽  
The Galaxy ◽  
Primary Cosmic Radiation ◽  
Order Of Magnitude ◽  
Medium Nuclei

Previous investigations by Daniel and Durgaprasad on the ratios Be/B and Be/Li in the primary cosmic radiation exploited the decay of 10Be produced in space to deduce a confinement time for cosmic rays in the galaxy. They concluded that this "age" T is at least 50 million years, and thence inferred that the cosmic-ray nuclei are trapped in a volume much larger than that of the galactic disk. These conclusions depended upon the values of fragmentation cross sections available in 1962 to Badhwar, Daniel, and Vijayalakshmi. Recent values of the Orsay group, however, reduce the calculated rates of 10Be and 9Be production by an order of magnitude; and an analysis based upon the latest cross sections leads to the following conclusions: (1) The possibility that cosmic rays are mainly confined to the disk of the galaxy and that T ≈ 106 years is not excluded. (2) The fragmentation parameter for medium nuclei [Formula: see text] into light nuclei [Formula: see text] is revised from 0.48 (the value of Badhwar et al.) to 0.34. (3) The mean path-length of 2.5 ± 0.5 g/cm2 of Badhwar et al. is revised to 4 ± 1 g/cm2. (4) 7Be now appears to be the principal component of cosmic-ray beryllium (about 70 or 80%, depending upon the cosmic-ray lifetime).

scholarly journals Measurement and interpretation of the isotopic composition of hydrogen and helium cosmic-ray nuclei below 75 MeV/nucleon

1968 ◽  
Vol 46 (10) ◽  
pp. S503-S508 ◽  
Author(s):  
J. P. Meyer ◽  
Donald E. Hagge ◽  
Frank B. McDonald
Keyword(s):  
Energy Dependence ◽  
Cross Sections ◽  
Cosmic Ray ◽  
Solar Modulation ◽  
Critical Survey ◽  
Propagation Models ◽  
Closed Model ◽  
Source Power ◽  
Section Data ◽  
Measured Ratio

The differential energy spectra of the hydrogen and helium isotopes of the galactic cosmic radiation have been measured in 1965 and 1966 by the highly eccentric satellites OGO I and IMP III. The energy ranges were respectively 20–50 and 30–90 MeV/nucleon.The measured ratio Γd = d/4He shows a very steep positive slope [Formula: see text] as a function of energy between 20 and 50 MeV/n. At 50 MeV/n, Γd is roughly 0.25. These results are in qualitative agreement with the measurements performed by the University of Chicago group on IMP III. The measured ratio ΓHe = 3He/4He is roughly 0.05 at 60 MeV/n, and decreases at lower energies.In order to understand the energy dependence of ΓHe and especially of Γd (Γd is not affected by the solar modulation), we investigated the creation of deuterons and 3He through fragmentation of cosmic-ray and interstellar 4He nuclei, and proton–proton reactions (assuming no injection of these isotopes at the source).We have used a Monte Carlo technique to propagate the cosmic-ray protons and 4He nuclei from the source to the earth. A critical survey of the available cross-section data has been made. The ionization loss, the energy dependence of the cross sections, and the reaction kinematics have been taken into account. The elastic scattering, acceleration in space, and solar modulation have not.We have systematically tried to fit the data with different source spectra and propagation models. Our present results completely rule out a total-energy, and favor a kinetic-energy source power spectrum. We discuss the bearing of different nonlocal propagation models (open model, closed model, injection at one time; different energy dependences of the mean "vacuum path-length") on Γd and ΓHe.

Cosmic-ray deuterium and helium-3 nuclei

1968 ◽  
Vol 46 (10) ◽  
pp. S627-S632 ◽  
Author(s):  
R. Ramaty ◽  
R. E. Lingenfelter
Keyword(s):  
Cross Sections ◽  
Solar Minimum ◽  
Path Length ◽  
Cosmic Ray ◽  
Unique Determination ◽  
The Earth ◽  
The Galaxy ◽  
Helium 3 ◽  
Field Modulation ◽  
Ray Path

Assuming that cosmic-ray deuterons and helium-3 nuclei are of secondary origin, we show that a unique determination of both the cosmic-ray path-length and the residual interplanetary field modulation at solar minimum may be made from a comparison of the calculated and measured intensities of these two nuclei. This determination does not depend on any assumptions regarding either the source spectra or the unmodulated proton to alpha particle ratio of the primary cosmic rays. The production of deuterium and helium-3 by cosmic-ray interactions in the galaxy is calculated considering energy-dependent cross sections, interaction kinematics, and demodulated cosmic-ray spectra. The resulting flux at the earth is obtained by taking into account leakage from the galaxy, ionization losses, nuclear breakup, and modulation. From a comparison of these calculations with the measured deuterium and helium-3 intensities at the earth, we conclude that within the experimental uncertainties all the data can be understood in terms of an energy-independent cosmic-ray path-length of 4 ± 1 g/cm2 and a residual interplanetary field modulation at solar minimum of the form exp(–η/Pβ) with η = 0.4 ± 0.1 BV, where P and β are the rigidity and velocity.

scholarly journals The composition of galactic cosmic rays

1968 ◽  
Vol 46 (10) ◽  
pp. S544-S547 ◽  
Author(s):  
D. V. Reames ◽  
C. E. Fichtel
Keyword(s):  
Cosmic Rays ◽  
Cross Sections ◽  
Length Distribution ◽  
Cosmic Ray ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Interstellar Space ◽  
Fermi Acceleration ◽  
Fixed Amount ◽  
The Galaxy

Recent measurements of low-energy galactic cosmic rays obtained on sounding rockets and satellites exhibit a composition different from that obtained for intermediate and high-energy radiation obtained at balloon altitudes. In particular the ratio of light to medium nuclei is observed to be 0.2–0.3 in the 50–100 MeV/nucleon interval as compared with values near 0.5 in the 200–500 MeV/nucleon region. Lower values of the ratios C/O, N/O, F/O, and odd-Z/even-Z are also found. In the light of these new measurements and of new measurements on the fragmentation cross sections for cosmic-ray nuclei in interstellar space, an attempt has been made to calculate the composition expected if similar source spectra are assumed. It is found that neither passage through a fixed amount of material nor an equilibrium condition (exponential path-length distribution) is adequate to explain the observed features. The effects of including other mechanisms such as rigidity-dependent escape from the galaxy and Fermi acceleration in interstellar space are evaluated.

scholarly journals A note on the relations between elastic and inelastic interactions and increasing ratio σel(s)/σtot(s) at the LHC

2019 ◽  
Vol 34 (32) ◽  
pp. 1950259 ◽  
Author(s):  
S. M. Troshin ◽  
N. E. Tyurin
Keyword(s):  
Elastic Scattering ◽  
Energy Dependence ◽  
Impact Parameter ◽  
Cross Sections ◽  
Parameter Dependence ◽  
Slope Parameter ◽  
Short Notice ◽  
Inelastic Interactions ◽  
The Impact ◽  
Mode A

We comment briefly on relations between the elastic and inelastic cross-sections valid for the shadow and reflective modes of the elastic scattering. Those are based on the unitarity arguments. It is shown that the redistribution of the probabilities of the elastic and inelastic interactions (the form of the inelastic overlap function becomes peripheral) under the reflective scattering mode can lead to increasing ratio of [Formula: see text] at the LHC energies. In the shadow scattering mode, the mechanism of this increase is a different one, since the impact parameter dependence of the inelastic interactions probability is central in this mode. A short notice is also given on the slope parameter and the leading contributions to its energy dependence in both modes.

scholarly journals The Origin and Dynamical Effects of the Magnetic Fields and Cosmic Rays in the Disk of the Galaxy

1970 ◽  
Vol 39 ◽  
pp. 168-183
Author(s):  
E. N. Parker
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Dynamical Behavior ◽  
Cosmic Ray ◽  
Interested Reader ◽  
Written Text ◽  
The Galaxy ◽  
Basic Ideas ◽  
The Magnetic Field

The topic of this presentation is the origin and dynamical behavior of the magnetic field and cosmic-ray gas in the disk of the Galaxy. In the space available I can do no more than mention the ideas that have been developed, with but little explanation and discussion. To make up for this inadequacy I have tried to give a complete list of references in the written text, so that the interested reader can pursue the points in depth (in particular see the review articles Parker, 1968a, 1969a, 1970). My purpose here is twofold, to outline for you the calculations and ideas that have developed thus far, and to indicate the uncertainties that remain. The basic ideas are sound, I think, but, when we come to the details, there are so many theoretical alternatives that need yet to be explored and so much that is not yet made clear by observations.

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