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Cosmic Ray Spectra Print


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Cosmic rays are a sample of solar, galactic and extragalactic matter which includes all known nuclei  and their isotopes, as well as electronspositrons, and antiprotons. They are associated with the most energetic events and active objects in the Universe: supernovae explosion, pulsars, relativistic jets, active galactic nuclei, although an unambiguous proof of their origin has not until now been found. The measurement of all particle cosmic ray energy spectrum, shown in figure, ranges for about 32 orders of magnitude in flux determination and more than 21 in explored energy. Three features appear in the spectrum, a first knee at an energy of 3 PeV, a second knee at about 0.5 EeV and an ankle beyond 10 EeV. In this spectrum there are, quite hidden, the answers to the main questions in the­ cosmic rays research. Where do the particles are coming from? How and where they are getting accelerated? How do they propagate through the interstellar medium and what kind of interaction do they encounter? What role do they play in the energy budget of the interstellar medium? Are they galactic or also extragalactic?

All particle cosmic ray spectrum
All particle cosmic ray spectrum

Understanding the origin, acceleration and propagation of cosmic rays in the Galaxy requires the combination of many different investigations over a wide range of energy, including chemical composition, anisotropy, and solar modulation.

PAMELA is accurately measuring the cosmic ray particle spectra in various components and in a wide energy range.



Edited by Laura Marcelli