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Point source (radioactive)that emits 100 gamma per second

  1. Nov 29, 2009 #1
    Hi all,
    i have a critical question.
    You have a point source (radioactive)..that emits 100 gamma per second. Now if you place a metal or foil (e.g., Al)..will the no. of gamma reduces??? If it reduces how to calculate..based on beer law..(if we know the attenuation coefficient of that metal and the energy of that 100 gamma)..sometimes i get confused with intensity and number of gamma quanta.
    thanks for your reply
  2. jcsd
  3. Nov 29, 2009 #2
    Re: attenuation

    it depends on the attenuation coefficient, if it is the total (i.e integrated over energy and all processes (pairproduction etc))
  4. Nov 29, 2009 #3
    Re: attenuation

    so no. of gamma quanta would decrease depending on the attenuation coefficient?
  5. Nov 29, 2009 #4
    Re: attenuation

    depends on if you have integrated atten coeff over energy etc
  6. Nov 30, 2009 #5
    Re: attenuation

    There are situations where a single high energy gamma from a radioactive source creates an electron positron pair, which in turn produces two annihilation gammas. So no, the attenuation does not always reduce the number of gammas. angstar is right, the attenuation coefficient can either apply either to the incident photon only, or to any photon of any energy comming out of the attenuator.
    Bob S
  7. Nov 30, 2009 #6
    Re: attenuation

    okay..something with exposure rate!..
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