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[RadCCORE Wiki Home Page :: Definitions :: This page]
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linear energy transfer |
'''Linear Energy Transfer''' (LET) is a measure of the energy transferred to material as an ionizing particle travels through it. Typically this measure is used to quantify the effects of ionizing radiation on biological specimens or electronic devices.
Damage to biological tissue by ionizing radiation is caused by energy absorption and the resulting ionization and excitation processes in the biological maicrostructures. the energy transfer to atoms and atomic nuclei can result in biochemical reactions with the molecules as well as in biological chages to cells or cell components. In addition to direct energy transfer by interaction, energy can be transferred indirectly to a molecule by radicals or their reaction poducts, such as hH2O2. Depending on the irradiation conditions, damage to the organism can result from the energy transfer and may extend to single organs, organ systems, or the whole body. The absorption of equal amounts of energy per unit mass under different irradiation conditions would not have the same biological effect. The severity an permanence of these changes are directly related to the local rate of energy deposition along the particle track, known as linear enery transfer (LET).
dE
L
L = _____
dl
For electronic devices for aerospace application this is typically expressed in units of
of material (The material in question is usually Si for MOS devices). The units of measurement arise from a combination of the energy lost by the particle to the material per unit path length (
) divided by the density of the material (
). [
http://radhome.gsfc.nasa.gov/top.htm ref[1] ] describes and quantifies the effects of radiation on electronic devices intended for use in space.
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Last modified: 13.09.07 by jross
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