A Measurement of Cosmic-Ray Rigidity Spectra above 5 GV/c of Elements from Hydrogen to Iron

Smith, Lloyd H.; Buffington, A.; Smoot, D. F.; Alvarez, Luis W.; Wahlig, M.

doi:10.1086/152021

Cited by 96 publications

(26 citation statements)

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“…These models are refined to bring them in agreement with an ever increasing body of direct interplanetary observations as well as solar photospheric measurements, e.g. Axford (1968Axford ( , 1972, Burlaga (1969Burlaga ( , 1971Burlaga ( , 1972, , Jokipii and Coleman (1968), Hedgecock (1975), , Schatten (1971), Sari and Ness (1969), Smith (1973), Wilcox (1969), Wilcox and Colburn (1969, 1970.…”

Section: Introductionmentioning

confidence: 99%

Observations of the eleven-year cosmic-ray modulation cycle

Moraal

1976

Space Sci Rev

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This paper reviews the available observations and the present state of knowledge of the long-term modulation of the intensity of galactic cosmic rays. This modulation occurs in response to the 11-year cycle of solar activity. The propagation of solar cosmic rays, as well as short-term modulation changes, are not explicitly discussed. The main theme of the paper is to interpret the observations in terms of the existing modulation theories. The theoretical model describes the propagation of cosmic rays in the interplanetary medium in terms of diffusion, convection, and energy changes. The topic is introduced with a brief description of how the cosmic-ray diffusion tensor is calculated from the fluctuations in the interplanetary magnetic field (Section 2). The cosmic-ray transport equations are discussed in Section 3. Observations of cosmic-ray intensity spectra, density gradients and anisotropies, and the evolution of the ll-year modulation cycle, are described in Sections 4, 5, and 6 respectively. It is shown that the principles of the modulation are understood in terms of the theoretical models. However, measurements of low-energy cosmic rays (kinetic energies ~< 50 MeV nucleon-t) during the last few years, indicate that the models may be incomplete. On the other hand, it is also pointed out that the available observations are not always sufficient to evaluate the full consequences of the theoretical models. In particular, we need observations out of the ecliptic plane, as well as an increased effort to measure the density gradients and anisotropies at a single position (e.g. Earth) and as function of time.

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Section: Introductionmentioning

confidence: 99%

Observations of the eleven-year cosmic-ray modulation cycle

Moraal

1976

Space Sci Rev

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“…In Figure 4.14, the observed ratios of sub-iron group to iron-group of nuclei are shown as a function of energy as given by Garcia-Munoz (1973). In this figure, different authors (Smith, et al, 1973b;Juliusson, 1974;Webber, et al, 1973c; have used different criteria in defining the charge groups and the observed scatter of points does not permit any definitive conclusions to be drawn as in the case from * for power law spectra in rigidity (Smith et al, 1973a) ** for power law spectra in kinetic energy per nucleon variation from about 2 GeV/n down to 30 MeV/n. Thus one can infer from…”

Section: Observed Change In the Abundances Of Secondary Nucleimentioning

confidence: 96%

“…At high energies, where the above difficulties do not exist, it is possible to obtain information on these aspects directly from observations. Indeed, the recent experimental investigations using different experimental techniques (Juiusson et al, 1972;Juliusson and Meyer, 1973;Smith et al, 1973a;Ormes and Balasubrahmanyan, 1973;Brown et al,1973b;Webber et al, 1973b) clearly indicate a change in the charge composition of cosmic rays at high energies. In this section we briefly present these experimental data and critically examine all the theoretical explanations put forth so far to understand these observations.…”

Section: Modification Of Energy Spectrum At High Energiesmentioning

confidence: 99%

“…Many of the explanations so far put forward are based on this principle (Juliusson et al 1972;Smith et al 1973a;Audouze and Cesarsky, 1973;Meneguzzi, 1973a;Ramaty et al 1973;Webber et al 1973b). …”

Section: Theoretical Models To Explain the Change In Compositionmentioning

confidence: 99%

“…Here, E" is the energy of the particle when it gives rise to a particle t m of energy E' and Q, (E') is the production spectrum of em nucleus directly as a function of mean energy (Casse et al, 1971;Brown et al, 1973a; O 'Dell et al, 1973;Smith et al, 1973a;Webber et al, 1973a;Juliusson, 1974). Also shown in the figure are two curves A and B representing the calculated values of the ratio for complete survival and decay respectively of the 10Be produced.…”

Section: Leakage Life Time From Long Lived Radio Nuclei In Cosmic Raysmentioning

confidence: 99%

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Propagation of cosmic rays in the galaxy

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The Knee in the Energy Spectrum of Cosmic Rays

Hörandel

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The knee in the all-particle energy spectrum is scrutinized with a phenomenological model, named poly-gonato model, linking results from direct and indirect measurements. For this purpose, recent results from direct and indirect measurements of cosmic rays in the energy range from 10 GeV up to 1 EeV are examined. The energy spectra of individual elements, as obtained by direct observations, are extrapolated to high energies using power laws and compared to all-particle spectra from air shower measurements. A cut-off for each element proportional to its charge Z is assumed. The model describes the knee in the all-particle energy spectrum as a result of subsequent cut-offs for individual elements, starting with the proton component at 4.5 PeV, and the second change of the spectral index around 0.4 EeV as due to the end of stable elements (Z = 92). The mass composition, extrapolated from direct measurements to high energies, using the poly-gonato model, is compatible with results from air shower experiments measuring the electromagnetic, muonic, and hadronic components. But it disagrees with the mass composition derived from X max measurements usingČerenkov and fluorescence light detectors.

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A Measurement of Cosmic-Ray Rigidity Spectra above 5 GV/c of Elements from Hydrogen to Iron

Cited by 96 publications

References 0 publications

Observations of the eleven-year cosmic-ray modulation cycle

Observations of the eleven-year cosmic-ray modulation cycle

Propagation of cosmic rays in the galaxy

The Knee in the Energy Spectrum of Cosmic Rays

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