Precision measurements of the positron component in the cosmic radiation provide important information about the propagation of cosmic rays and the nature of particle sources in our Galaxy. The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmicray positron flux and fraction that extends previously published measurements up to 300 GeV in kinetic energy. The c...

The interaction cross-section is one of the fundamental properties of any elementary particle. For decades, only accelerator measurements of the particle cross-sections were available. Crosssection measurements at higher and higher energy become possible as more and more powerful accelerators are introduced. However, cosmic rays not only provide a constant flux of ultra highenergy particles, bu...

The investigation of very high energy cosmic rays and their interactions are inherently connected subjects of astroparticle physics. On one hand the understanding of cosmic ray interactions is needed to study the flux, acceleration and propagation of cosmic rays. For example, the high energy cosmic ray flux can only be measured by linking secondary particle cascades observed in detectors or the...

In this paper we present fluxes of galactic cosmic ray nuclei with energies above 40 MeV/n observed by the Kiel Electron Telescope on board the Ulysses spacecraft during the fast scan from the South Pole (September 1994) to the North Pole (July 1995). This part of the Ulysses orbit gives us the unique opportunity to investigate spatial modulation of cosmic rays under solar minimum conditions. W...

The well established cosmic ray transport equation describes the physics of cosmic ray modulation in the heliosphere and is thought to be complete. Its solution for anomalous cosmic rays has special characteristics due to the local acceleration of these particles at the solar wind termination shock. Some of these characteristics are demonstrated here, namely effects by the strength of the shock...

At energies below ~300 MeV/nuc our knowledge of cosmic-ray spectra outside the heliosphere is obscured by the energy loss that cosmic rays experience during transport through the heliosphere into the inner solar system. This paper compares measurements of secondary electron-capture isotope abundances and cosmic-ray spectra from ACE with a simple model of interstellar propagation and solar modul...

The cosmic ray all-particle spectrum has a small steepening of its spectral slope, or ‘knee’, near 10 eV. Changes in the nuclear composition of cosmic rays may be associated with the knee and provide clues concerning the origin of the spectral change. An ultra-long duration balloon experiment, Cosmic Ray Energetics and Mass (CREAM), is being constructed to measure cosmic ray elemental spectra a...

[1] We present a re-evaluation of the hypothesis of a coupling between galactic cosmic rays, clouds and climate. We have used two independent estimates of low cloud cover from the International Satellite Cloud Climatology Project, covering 16.5 years of data. The cloud cover data are used in conjunction with estimates of galactic cosmic ray flux and measurements of solar irradiance. It is found...

[1] Although controversial, many observations have suggested that low-level cloud cover correlates with the cosmic ray flux. Because galactic cosmic rays have likely decreased in intensity over the last century, this hypothesis, if true, could partly explain 20th century warming, thereby upsetting the consensus view that greenhouse-gas forcing has caused most of the warming. The ‘‘ion-aerosol c...

Cosmic ray induced ionization (CRII) is an important factor of outer space influences on atmospheric properties. Variations of CRII are caused by two different processes – solar activity variations, which modulate the cosmic ray flux in interplanetary space, and changes of the geomagnetic field, which affects the cosmic ray access to Earth. Migration of the geomagnetic dipole axis may greatly a...