Astrophysics (Index)About

cosmic rays

(very-high-energy particles from beyond the solar system)

Cosmic rays are high energy particles, typically with energies distributed around 0.3 GeV (4.8 × 10-11 joule), but the highest energy have been up to 3 × 1011 GeV. The term cosmic ray was coined when detectors were developed that demonstrate they continually fall on Earth, and the term traditionally included photons. However, common astrophysics usage has come to use EMR terminology for such photons, and reserve the term cosmic ray for other particles, including protons, heavier nuclei (such as alpha particles) electrons, with other particles such as neutrinos sometimes included when they have similar energies. They are theorized to be formed largely by supernovae. Cosmic rays are continually arriving, i.e., as the cosmic ray background (CRB), but that phrase is not commonly used perhaps because all known cosmic rays fit that description.

Some classes of cosmic-ray particles by kinetic energy (KE):

A famous graph, the Swordy plot demonstrates that cosmic rays occur basically with a power law spectrum over a wide range. Particles approaching Earth (i.e., before the effects of the atmosphere) arrive rates of roughly a 1-GeV particle per square meter per three hours falling such that there's roughly a 10-PeV particle per square meter every four months.

Cosmic ray astronomy makes use of space-based observatories such as INTEGRAL, and ground detectors such as LOPES, and Milagro. At high energies, the type of particle is often not evident, merely the KE, and the abundances of proton cosmic ray particles versus heavier nuclei or other particles at particular energies is of research interest. There is something of an assumption that they are protons, without evidence to the contrary.

Further reading:

Referenced by pages:
Advanced Composition Explorer (ACE)
anomalous cosmic rays (ACR)
air shower
alpha particle
ARGO-YBJ Experiment
black hole (BH)
cosmic background radiation (CBR)
Cherenkov detector
electrostatic barrier
electron volt (eV)
Fenton Hill Observatory (FHO)
gamma rays (GR)
GZK limit
high-energy astrophysics (HEA)
ionizing radiation
lithium (Li)
Lunar Reconnaissance Orbiter (LRO)
multi-messenger astronomy
neutron scattering
neutron spectrometer
Oh-My-God Particle
Orbiting Wide-angle Light Collectors (OWL)
Pierre Auger Observatory (PAO)
power law
radioactive dating
relativistic astrophysics
solar energetic particle (SEP)
Tunka experiment
Telescope Array Project (TA)
tau neutrino (ντ)
Van Allen belts