Rotational Seismology
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RADIATION HAZARDS
anomaly cosmic rays, and outside the Heliosphere – mainly galactic cosmic rays.
Lev I. Dorman Israel Cosmic Ray and Space Weather Center and Emilio Segre' Observatory, Tel Aviv University, TECHNION, and Israel Space Agency, Qazrin, Israel IZMIRAN of Russian Academy of Sciences, Troitsk, Moscow region, Russia
The basic unit of radiation dose The basic unit for radiation dose is rad, defined in terms of the energy (in ergs or J) deposited by radiation per unit mass (gramm or kg) of exposed matter: 1 rad = 100 erg/g = 0.01 J/kg.
Definition Radiation hazards for people and technology are determined by electromagnetic radiation (from intense radio waves up to UV, X-rays, and g-rays) and by fluxes of corpuscular radiation (energetic protons, neutrons, nucleous, electrons, pions, muons, and in case of nearby Supernova even by great fluxes of neutrino, see Supernova). Main sources Radiation hazards for people and technology on the ground and at different altitudes in atmosphere are determined by natural sources (mainly from galactic and solar cosmic rays and from radioactive elements in soil and in air) and by artificial (man-made) sources which generate different types of electromagnetic and corpuscular radiation (from home-used devices such as TV, microwave heaters, mobile phones to atomic and H-bomb explosions). With an increase of altitude, the natural radiation hazard from cosmic rays increases considerably and from radioactive elements – sufficiently decreases. For satellites and astronauts situated in the magnetospheres of the Earth and other planets (especially as Jupiter and Saturn), important natural sources of radiation hazard are cosmic rays and radiation belts; for spaceprobes and astronauts inside the Heliosphere – galactic, solar, planetary, and
Relative biological effectiveness of different types of radiation Different types of radiation have very different influence on human health. As a result the special factor relative biological effectiveness (RBE), averaged for full body, was introduced. For X-rays, g-rays, and energetic electrons RBE = 1, for thermal neutrons RBE = 3, for energetic neutrons, protons, and a-particles RBE = 10, and for energetic nucleus heavier than a-particles RBE = 20. Therefore, the unit of radiation, effectively influenced on people is rem (Roentgen Equivalent to Man), defined as rem = RBE rad = 0.01 seivert. The unit seivert was named after Rolf Sievert (1898–1966), a pioneering Swedish radiation physicist. Effects of radiation on people The large radiation dose which can kill outright is about 5,000 rem (so-called Instant Death). The radiation dose near 900 rem leads to death over the course of one day (so-called Overnight Death). The dose approximating 500 rem causes severe radiation sickness (nausea, hair loss, skin lesions, etc.) as the body’s short-lived cells fail to provide new generations to replace their normal mortality (cell reproductive death). It is not this trauma which usually kills, however, but the complications that arise from a lack of r
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