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Gamma rays : shielding

  1. Nov 10, 2005 #1
    can electromagnetic shielding in space protect humans (for a long period) from gamma radiation??
  2. jcsd
  3. Nov 10, 2005 #2
    No, gamma radiation is neutral and no electromagnetism will protect humans from it. Solid shielding is required.
  4. Nov 11, 2005 #3
    But please tel me more about this SOLID SHIELDING required.
  5. Nov 11, 2005 #4


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    Staff: Mentor

    Gamma rays interact primarily with the electrons in matter, primarily through the Compton effect (http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/comptint.html#c1), but also the photoelectric effect (http://hyperphysics.phy-astr.gsu.edu/hbase/mod1.html#c2).

    At gamma energies above 1.022 MeV, pair (e+, e-) prodcution is possible, whereby the gamma photon interacts with the nucleus to form an electron-positron pair. The electron and positron will interact with other electrons to slow down, and ultimately the positron will combine with an electron in mutual annihilation (transformation) into two gamma rays of ~ 0.511 MeV.

    Now an effective shield for gamma-radiation should maximize the electron density, and that is why lead is used - it also happens to be relatively inexpensive to other heavy (dense) elements. Thorium and uranium would be good shield materials by this criterion, but they are also radioactive themselves.

    The tradeoff for shielding is the mass.

    The effect of high energy charged particles is more of a concern in space.
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