Upper Limits on Low Energy Cosmic Ray Protons and Heavy Nuclei in Interstellar Space

Nature ◽  
1968 ◽  
Vol 220 (5171) ◽  
pp. 1015-1016 ◽  
Author(s):  
M. V. K. APPARAO
Keyword(s):  
Cosmic Ray ◽  
Low Energy ◽  
Interstellar Space ◽  
Heavy Nuclei ◽  
Upper Limits

scholarly journals Composition and Galactic Confinement of Cosmic Rays

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.

The MACRO Experiment

2003 ◽  
Vol 18 (29) ◽  
pp. 2001-2018 ◽  
Author(s):  
G. Giacomelli ◽  
A. Margiotta
Keyword(s):  
Atmospheric Neutrino ◽  
Cosmic Ray ◽  
High Energy ◽  
Magnetic Monopoles ◽  
Low Energy ◽  
Muon Neutrino ◽  
High Energy Muon ◽  
Upper Limits ◽  
Neutrino Astronomy

In this paper we describe the main results obtained by the MACRO experiment: final stringent upper limits on GUT magnetic monopoles and nuclearites, results on atmospheric neutrino oscillations, high energy muon neutrino astronomy, searches for WIMPs, search for low energy stellar gravitational collapse neutrinos, several studies with high energy downgoing muons and determination of the primary cosmic ray composition at knee energies.

The low-energy cosmic-ray nuclei and their propagation in interstellar space

1968 ◽  
Vol 46 (10) ◽  
pp. S553-S556 ◽  
Author(s):  
G. M. Comstock
Keyword(s):  
Additional Data ◽  
Cosmic Ray ◽  
Low Energy ◽  
Energy Spectra ◽  
Interstellar Space ◽  
Loss Measurement ◽  
Depletion Depth ◽  
Two Component ◽  
The University ◽  
Component Models

The differential energy spectra of the cosmic-ray nuclei helium, carbon, nitrogen, and oxygen above 30 MeV/nucleon, boron, neon, magnesium, and silicon above 50 MeV/nucleon, and the iron group above 100 MeV/nucleon, measured in October–December 1964 and May–June 1965 by the University of Chicago charged-particle telescope on board the OGO-I satellite (Comstock et al. 1966b), have been corrected to take account of the effective depletion depth of the gold–silicon solid-state detectors used for rate-of-energy-loss measurement. Additional data from October to December 1965 are included. The magnitudes and relative shapes of the spectra deduced by extrapolation to nearby interstellar space place important constraints on the allowed modes of interstellar propagation for these nuclei. Two-component models are shown to account for most of the observed properties of the interstellar cosmic-ray nuclei.

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.

The search for cosmic-ray anisotropies

1975 ◽  
Vol 277 (1270) ◽  
pp. 381-393 ◽  
Keyword(s):  
Magnetic Field ◽  
Cosmic Ray ◽  
Interstellar Space ◽  
Galactic Rotation ◽  
Cosmic Ray Intensity ◽  
Solar Motion ◽  
Upper Limits ◽  
The Mean ◽  
High Degree ◽  
Small Anisotropy

At the present time there is no generally accepted evidence for any statistically significant anisotropy in the energy range 1017-1019 eV. The upper limits on the possible anisotropy provide strong evidence that these particles are extra-galactic. In that part of the cosmic-ray magnetic rigidity spectrum below ca . 2 x 1011 V the interplanetary magnetic field effectively prevents the detection of anisotropies in interstellar space and the only isotropies measured are associated with the solar wind and its associated magnetic field. In the range of magnetic rigidities extending from 1011 to 1012 V the cosmic-ray intensity shows evidence for a small anisotropy of about 2 x 10~4 which can be explained as the result of solar motion relative to the average galactic rotation in our neighbourhood. When this is removed the residual deviations from the mean intensity preclude any systematic sinusoidal variation greater than 2 x 10~4. This high degree of isotropy is most easily understood if these particles are members of an extra-galactic population and it is suggested that this extra-galactic component predominates from the highest cosmic-ray energies down the spectrum at least as far as ca . 1011 V rigidity.

Low-energy cosmic-ray heavy nuclei during the time of solar minimum

1968 ◽  
Vol 46 (10) ◽  
pp. S598-S600
Author(s):  
E. Tamai ◽  
M. Tsubomatsu ◽  
K. Ogura
Keyword(s):  
Energy Range ◽  
Solar Minimum ◽  
Cosmic Ray ◽  
Low Energy ◽  
Energy Spectra ◽  
Solar Modulation ◽  
Atmospheric Depth ◽  
Heavy Nuclei ◽  
Multiply Charged ◽  
Α Particles

Nuclear emulsions were exposed at 2.3 g cm−2 atmospheric depth over Fort Churchill in 1965. These emulsions have been examined for the tracks of multiply-charged [Formula: see text] nuclei, with emphasis being paid particularly to those particles that stopped in the emulsions. Differential energy spectra of α particles and [Formula: see text], [Formula: see text]and [Formula: see text] nuclei were obtained in the energy interval 60–550 MeV/nucleon. They represent experimental results during the period when solar modulation effects were at a minimum. The fluxes of α particles and L, M, and H nuclei for energy intervals of 60–170, 100–400, 100–525, and 140–550 MeV/nucleon were found to be 20.9 ± 1.2, 2.4 ± 0.4, 4.8 ± 0.6, and 2.5 ± 0.4 particles m−2 sr−1 s−1, respectively. The results also show that the L/M and H/M ratios at the top of the atmosphere were 0.56 ± 0.16 and 0.34 ± 0.13 respectively, in the energy range from 140 to 350 MeV/nucleon. These values are appreciably greater than those observed at higher energies.

Galactic ?-ray Lines Resulting from Interactions Between Low Energy Cosmic Rays and the Interstellar Medium

1979 ◽  
Vol 32 (4) ◽  
pp. 383 ◽  
Author(s):  
Masato Yoshimori
Keyword(s):  
Cosmic Rays ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
Crab Nebula ◽  
Cosmic Ray ◽  
Low Energy ◽  
Longitudinal Distribution ◽  
Galactic Centre ◽  
Interstellar Space ◽  
Interstellar Gas

Calculated spectral profiles and galactic distributions are presented for y-ray lines resulting from interactions between low energy cosmic rays and the interstellar gas and dust. Calculated local intensities are also presented for y-ray lines from discrete sources such as supernova remnants and dense interstellar gas clouds. The y-ray lines from excited dust nuclei (which have long mean lifetimes) are sharp, having widths of the order of a few keV; the lines from excited gas nuclei are relatively narrow, having widths of the order of 100 keV; and the lines from excited cosmic ray nuclei are broad, having widths of the order of 1 MeV. The longitudinal distribution of y-ray lines in the galactic plane shows a significant concentration toward the galactic centre, and a rapid falloff beyond I;. 50�. The most intense y-ray lines arise from positron annihilation (0�511 MeV) and the deexcitation of 12C* (4�439 MeV) and 160* (6�131 MeV). In the direction of the galactic centre, these lines have estimated intensities of the order of 10-5 photons cm-2s-1rad- 1, and so they may be resolved from the diffuse y-ray background there by observing with a high resolution Ge(Li) detector. In the direction of several strong discrete sources, the estimated fluxes are generally lower: ~10-6 photons cm-2s-1 for the Crab Nebula and the Vela pulsar, ~10-8 photons cm-2 s-1 for the interstellar dense cloud pOph, but ~10-5 photons cm-2 s-1 for the ring cloud around the galactic centre. The calculated intensities of various other y-ray lines are compared with available experimental data, and their detectability is considered. The implication of the galactic distribution of low energy cosmic rays for the gas density of the interstellar space through which the cosmic rays propagate is also discussed.

scholarly journals Experimental Examination of Low-Energy Cosmic-Ray Heavy Nuclei

1965 ◽  
Vol 138 (3B) ◽  
pp. B732-B739 ◽  
Author(s):  
C. E. Fichtel ◽  
D. E. Guss ◽  
K. A. Neelakantan
Keyword(s):  
Cosmic Ray ◽  
Low Energy ◽  
Heavy Nuclei ◽  
Experimental Examination

Quantum effects in low-energy photofission of heavy nuclei

1984 ◽  
Vol 144 (9) ◽  
pp. 3 ◽  
Author(s):  
Yurii M. Tsipenyuk ◽  
Yu.B. Ostapenko ◽  
G.N. Smirenkin ◽  
A.S. Soldatov
Keyword(s):  
Quantum Effects ◽  
Low Energy ◽  
Heavy Nuclei

Time-resolved ion cyclotron resonance

1978 ◽  
Vol 364 (1718) ◽  
pp. 367-381 ◽  
Keyword(s):  
Cyclotron Resonance ◽  
Low Energy ◽  
Interstellar Space ◽  
Ion Cyclotron Resonance ◽  
Absolute Rate ◽  
Time Resolved ◽  
Ion Molecule Reactions ◽  
Quadrupole Trap ◽  
Ion Cyclotron ◽  
Improved Technique

Ion cyclotron resonance (i. c. r.) is a technique for the study of ion-molecule reactions in the collisional range from thermal to several electron volts. The study of these reactions at low energy has been given impetus by the discovery of their importance in the ionosphere and in interstellar space. This communication identifies some possible weaknesses inherent in current i. c. r. work and suggests an improved technique with which it is possible to determine absolute rate constants more reliably. As an illustration of the technique a measurement of the rate constant for the reaction CH 4 + + CH 4 → k CH 5 + + CH 3 is presented. This value is k = 1.21 ± 0.09 × 10 -15 m 3 s -1 . A new i. c. r. cell design is discussed with which it is hoped to provide further improvement in reliability by the production of a homogeneous radiofrequency field within a true quadrupole trap.

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