Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate Earth's atmosphere and surface.The term ray is historical as cosmic rays were thought to be electromagnetic radiation. Most primary cosmic rays (those which impact the atmosphere from deep space) are composed of familiar stable particles that normally occur on Earth, such as protons, atomic nuclei, or electrons. However, a very small fraction are stable particles of antimatter, such as positrons orantiprotons, and the nature of this remaining fraction is an area of active research.
About 89% of cosmic rays are simple protons or hydrogen nuclei, 10% are helium nuclei or alpha particles, and 1% are heavier elements. These nuclei constitute 99% of the cosmic rays. Solitary electrons (much like beta particles, although their ultimate source is unknown) constitute much of the remaining 1%.
The variety of particle energies reflects the wide variety of sources. The origins of these particles range from processes on the Sun (and presumably other stars as well), to as yet unknown physical mechanisms in the farthest reaches of the visible universe. Cosmic rays can have energies of over 1020 eV, far higher than the 1012to 1013 eV that Terrestial particle accelerators can produce. There has been interest in investigating cosmic rays of even greater energies.
Cosmic rays have a primary role in the formation of the lithium, beryllium, and boron in the universe, through the process of "cosmic ray nucleosynthesis". They also produce some radioisotopes on Earth, such as carbon-14. In the history of particle physics, cosmic rays were the source of the discovery of the positron, muon, and pi meson. Cosmic rays compose a large part of natural background radiation on Earth. Since the intensity of cosmic rays is much larger outside the Earth's atmosphere and magnetic field, it is expected to have a major impact on the design of spacecraft that can safely transport humans in interplanetary space.
The Alpha Magnetic Spectrometer, also designated AMS-02, is a particle physics experiment module that is mounted on theInternational Space Station. It is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments will help researchers study the formation of the Universe and search for evidence of dark matter as well as investigate antimatter. Theprincipal investigator is Nobel laureate particle physicist Samuel Ting. After final testing at ESA's European Space Research and Technology Centre (ESTEC) facility in the Netherlands, delivery to the Kennedy Space Center in Florida took place on August 26, 2010. The launch of Space Shuttle Endeavour flight STS-134 carrying AMS-02 took place on 16th May 2011, and the spectrometer was installed on 19 May 2011.
Samuel Chao Chung Ting (Chinese: 丁肇中; pinyin: Dīng Zhàozhōng; Wade-Giles: Tin Chao-chung) (born January 27, 1936) is a Taiwanese American physicist who received the Nobel Prize in 1976, with Burton Richter, for discovering the subatomic J/ψ particle. He is the principal investigator for the international $1.5 billion Alpha Magnetic Spectrometer experiment which was installed on the International Space Station on 19 May 2011.