All the components of cosmic rays have 'structure' in their energy spectra at some level, ie deviations from a simple power law, and their examination is relevant to the origin of the particles. ...Emphasis, here, is placed on the large-scale structures in the spectra of nuclei (the 'knee' at about 3 PeV), that of electrons and positrons (a shallow 'upturn' at about 100 GeV) and the positron to electron plus positron ratio (an upturn starting at about 5 GeV). Fine structure is defined as deviations from the smooth spectra which already allow for the large-scale structure. Search for the fine structure has been performed in the precise data on positron to electron plus positron ratio measured by the AMS-02 experiment. Although no fine structure is indicated, it could in fact be present at the few percent level.
Does the Sun affect the Earth's climate? Priest, Eric; Lockwood, Mike; Solanki, Sami ...
Astronomy & geophysics : the journal of the Royal Astronomical Society,
June 2007, Letnik:
48, Številka:
3
Journal Article
We argue that the cosmic ray positron excess observed in ATIC-2, Fermi LAT, PAMELA, HESS and recently in the precision AMS-02 experiment can be attributed to the production in a local, middle-aged ...supernova remnant (SNR). Using the prediction of our model of cosmic ray acceleration in SNR we estimate that the SNR responsible for the observed positron excess is located between 250 and 320pc from the Sun and is 170-380 kyear old. The most probable candidate for such a source is the SNR which gave birth to the well-known Geminga pulsar, but is no longer visible. Other contenders are also discussed.
Peter Howard Fowler FRS 1923–1996 Wolfendale, Arnold
Astronomy & geophysics : the journal of the Royal Astronomical Society,
08/1997, Letnik:
38, Številka:
4
Journal Article
The dependence of the cosmic ray intensity on Galactocentric distance is known to be much less rapid than that to be thought-to-be sources: supernova remnants. This is an old problem ('the radial ...gradient problem') which has led to a number of possible 'scenarios'. Here, we use recent data on the supernova's radial distribution and correlate it with the measured HII electron temperature ({\em T}). We examined two models of cosmic ray injection and acceleration and in both of them the injection efficiency increases with increasing ambient temperature {\em T}. The increase is expected to vary as a high power of {\em T} in view of the strong temperature dependence of the tail of the Maxwell-Boltzmann distribution of particle energies. Writing the efficiency as proportional to \(T^n\) we find \(n\approx 8.4\). There is thus, yet another possible explanation of the radial gradient problem.
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