Cosmic-Ray Hydrogen and Helium Nuclei during a Solar Quiet Time in July 1961

Fichtel, C. E.; Guss, D. E.; Stevenson, G.; Waddington, C. J.

doi:10.1103/physrev.133.b818

Cited by 27 publications

(15 citation statements)

References 42 publications

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“…Vogt and Meyer have interpreted this excess as possibly due to a steady solar particle emission at low rigidities or as due to protons ejected by large flares and stored for long periods in interplanetary space. Other measurements made during this later period with emulsions and counters [Fichtel et al, 1964;Bryant et al, 1962] suggest a proton spectrum somewhere between that of Vogt and Meyer and the earlier McDonald and Webber results.…”

Section: Introduction a Detailed Knowledge And Com-supporting

confidence: 62%

“…Recently a number of measurements have been made on low rigidity protons by both counter techniques and emulsions. Comparable measurements were made with these techniques during July-August 1961 [Meyer and ¾ogt, 1963;Fichtel et al, 1964]. Their results, shown in Figure 7, can be directly compared with the .a-particle spectrum also given in Figure 7 (see also Table 1).…”

Section: While We Cannot Reject Elllot's Model On the Basis Of Cosmicmentioning

confidence: 99%

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Cerenkov scintillation ounter measurements of the intensity and modulation of low rigidity cosmic rays and features of the geomagnetic cutoff rigidity

Webber¹,

McDonald²

1964

J. Geophys. Res.

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The primary cosmic radiation has been measured with a Cerenkov scintillation counter at various times in the solar cycle at locations having nominal cutoff rigidities of 0.8, 1.6, and 2.7 bv. Results are used here to delineate spectral features of low rigidity protons and α particles and to examine the rigidity and charge dependence of the eleven‐year solar modulation. Details of particle transmission near the geomagnetic cutoff are also examined. The measurements indicate: (1) The observed nonsharp cutoff appears to be primarily due to expected transmission effects in a dipole‐like field and to instrumental effects, and the actual cutoff is quasi‐sharp in the Störmer sense. This is true even though the observed cutoff may be reduced to half that to be expected from the internal field, presumably because of external current systems flowing in the magnetosphere and its boundary. (2) The rigidity dependence of the eleven‐year modulation of protons and that of α particles are closely similar above ∼1.2 bv. None of the presently proposed models for this modulation agree with our results. The implications of this lack of agreement are discussed, and it is concluded that certain general features of particle motion in the interplanetary medium not considered in present models may be of importance. One such general feature may be diffusive deceleration in the radially expanding interplanetary medium, which is shown to have the same effect as a static heliocentric electric field. (3) The differential spectrum of galactic cosmic rays near sunspot minimum at about 1‐bv rigidity is either flat or falling slightly toward lower rigidities. The measurements in the rigidity range below 1 bv are compared with recent observations in this range.

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Section: Introduction a Detailed Knowledge And Com-supporting

confidence: 62%

Section: While We Cannot Reject Elllot's Model On the Basis Of Cosmicmentioning

confidence: 99%

Cerenkov scintillation ounter measurements of the intensity and modulation of low rigidity cosmic rays and features of the geomagnetic cutoff rigidity

Webber¹,

McDonald²

1964

J. Geophys. Res.

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show abstract

“…7 Figure 2 compares the results of this experiment with those obtained from an emulsion detector flown in 1961, 3 and shows that there has been a definite increase in intensity of both components which is presumably associated with the decline in solar activity from 1961 and 1963. This result appears to be in contradiction with the decrease in intensity observed by Meyer and Vogt, 1 using counter detectors, between 1960 and 1961.…”

mentioning

confidence: 89%

“…In the past few years, the low-energy proton component of the primary cosmic radiation has been measured in a number of separate experiments. 1 " 3 The results of these experiments have not been in complete agreement, and although some of the discrepancies have almost certainly been due to temporal variations, it seems highly likely that experimental effects have also been present. Among the most interesting questions that can be sutdied in these experiments is whether the constant value of approximately 7.0 for the ratio of protons to a particles at a given rigidity, known to hold at rigidities above 2.0 BV, still holds at lower rigidities.…”

mentioning

confidence: 91%

“…The observation of a variation in this ratio has important consequences in any theory of the modulation or propagation of cosmic-ray particles in the solar system. 3 For these reasons a new investigation has been made of the low-energy protons and a particles in the primary radiation, using a nuclear emulsion detector with limited temporal resolution. In this detector a stack of nuclear emulsions was mounted in a device which rearranged the orientation of the emulsions at a preset time.…”

mentioning

confidence: 99%

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