-- NigelWatson - 07 Sep 2010

Cosmic Rays

Cosmic rays are high energy charged particles that originate in outer space, (mainly from supernova explosions but also from stars see "where do cosmic rays come from" to read more) travel at the speed of light and strike the Earth from all directions.

They strike the Earth's surface at the rate of about 1 cosmic ray every square centimetre every minute. Perhaps a more meaningful way to look at this is that during an average nights sleep a person will have on average of a million cosmic rays traveling through their body!

Cosmic Rays typically have energies ranging between 106 - 1020 eV (around 10-13 - 10-10 Joules). Although in these terms this does not sound a very large amount of energy, the energy is very concentrated; the particles are extremely small (typically 10-29kg and of the order 10-18m in radius, or 0.000000000000000001 metres in radius) it can be appreciated that this is a large energy for each of these minute particles to have.

Cosmic rays are very penetrating; so much so that they have also been detected under the ground, such as in the London Underground system and down deep mines. We can get Primary and Secondary Cosmic Rays, to be discuessed later on. The table below is included to allow comparisons of penetrating ability of types of radiation.

Cosmic Rays are very useful in many areas of science e.g.:

  • Due to their high energy they can be used to smash atoms so we can learn more about their internal stucture and PartIcles in general
  • The source of cosmic rays is of intrest to astronomers and cosmologists (see the University of Birmingham Astrophysics web page: http://www.sr.bham.ac.uk )
  • Radiocarbon dating resulted from cosmic ray research (see http://www.cq.rm.cnr.it/c-14.html )
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Topic revision: r3 - 13 Sep 2010 - _47C_61UK_47O_61eScience_47OU_61Birmingham_47L_61ParticlePhysics_47CN_61nigel_32watson?
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