Charged Cosmic Rays in Our Galaxy

This chapter introduces the primary Cosmic Rays (CRs). Primary CRs are high-energy and stable particles originating in astrophysical environments. They are protons, fully ionized atomic nuclei and electrons. Part of the primary radiation can interact in (or close to) the acceleration regions producing other high-energy charged and neutral secondary particles. Antiparticles (mainly positrons and antiprotons) are also present in the cosmic radiation, but in most cases, they are originated during the propagation of primary protons and electrons. All the particles produced far from the acceleration regions during the propagation of primary CRs, or produced on their arrival in the Earth’s atmosphere, are denoted as secondary CRs. Particle detectors play a fundamental role in the history of CRs. As described, the intensity of this ionizing radiation is modulated by the solar activity. Below a few tens of GeV, the primary CR flux arriving on Earth also depends on the magnetic latitude, as it is affected by the geomagnetic field. The theoretical models on the origin of CRs rely on many astrophysical parameters and experimental observations about nature, energy density, confinement time, and chemical composition of CRs as a function of their energy.