We review the current state and future prospect of ultra high energy cosmic ray physics and the relationship between cosmic rays and gamma-ray astrophysics.

There is an increasing amount of evidence linking biological effects to solar and geomagnetic disturbances. A series of studies is published referring to the changes in human physiological responses at different levels of geomagnetic activity. In this study, the possible relation between the daily variations of cosmic ray intensity, measured by the Neutron Monitor at the Cosmic Ray Station of t...

The observed correlation between global low cloud amount and the flux of high energy cosmic-rays supports the idea that ionization plays a crucial role in tropospheric cloud formation. We explore this idea quantitatively with a simple model of cosmic-ray ionization enhancement of the formation of cloud condensation nuclei. This model predicts that solar modulation of the cosmic-ray ionization r...

In this article, cosmic ray acceleration is studied in a nonlinear test particle picture in the hydrodynamic approach. The model includes cosmic rays and two oppositely propagating Alfvén waves. It is a nonlinear model because the interactions between the cosmic rays, waves and background plasma depend on the waves themselves. The background is a simple fast shock. Besides the parameters charac...

An extragalactic origin of the dominant part of all extrasolar hadronic cosmic rays above about 10MeV/nucleon has long been considered unlikely due to energy considerations. In order to circumvent such arguments, the hypothesis that “flux trapping” of extragalactic cosmic rays occurs in the Galactic confinement volume is advanced in this paper. This hypothesis is based on a number of speculativ...

Since 1950’s there has been a growing interest of understanding the effects of cosmic ray radiation on the increase in average global temperature. Recent studies showed that galactic cosmic rays play a significant role in the formation of low cloud coverage and its consequent impact on the global temperature variation of the earth. A long-term measurement of the cosmic ray flux distribution at ...

The study of Galactic diffuse γ radiation combined with the knowledge of the distribution of the molecular hydrogen in the Galaxy offers a unique tool to probe the cosmic ray flux in the Galaxy. A methodology to study the level of the cosmic ray "sea" and to unveil target-accelerator systems in the Galaxy, which makes use of the data from the high resolution survey of the Galactic molecular clo...

Supernova remnants are likely to be the accelerators of the galactic cosmic rays. Assuming the correctness of this hypothesis, we develop a method to extract the parent cosmic ray spectrum from the VHE gamma ray flux emitted by supernova remnants (and other gamma transparent sources). Namely, we calculate semi-analytically the (inverse) operator which relates an arbitrary gamma ray flux to the ...

Two vertical cosmic ray telescopes for atmospheric cosmic ray ionization event detection are compared. Counter A, designed for low power remote use, was deployed in the Welsh mountains; its event rate increased with altitude as expected from atmospheric cosmic ray absorption. Independently, Counter B's event rate was found to vary with incoming particle acceptance angle. Simultaneous co-located...

A report is given on the status and recent results from the HEGRA imaging atmospheric Cherenkov telescopes (IACT) concerning Mrk 501 and GRS 1915+105 and on recent results from the HEGRA arrays concerning galactic and extragalactic γ-sources, counterparts of TeV Gamma-Ray-Bursts, cosmic ray anisotropies, energy spectrum and composition of primary cosmic rays. The report summarizes the presentat...