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Calculation of neutron transport cross section

  1. Jul 12, 2013 #1
    I have a book on nuclear reactions which details the mean free paths for thermal neutron scattering as:
    0.37cm for water and
    2.2cm for heavy water

    The transport cross sections are listed as 0.45cm for water and 2.6cm for heavy water. Does anyone know how to calculate these from the thermal scattering cross sections?

  2. jcsd
  3. Jul 12, 2013 #2
    macroscopic transport cross section=macroscopic scattering cross section *(1-cos(theta))
    or generally
    macroscopic cross section=1/mean free path

    for water 1-cos(theta)=0.324 and 0.116 for heavy water
  4. Jul 12, 2013 #3
    Where do these values of 1-cos(theta) come from?

    If I use them, I obtain very different values of transport cross section than those in my book. These values of 1-cos(theta) give 1.14cm for water and 19.16cm for heavy water?
  5. Jul 12, 2013 #4
  6. Jul 13, 2013 #5
    Thanks for the text, it was useful.

    However, I am still unable to arrive at the values for the transport mean free paths which were stated in my book on nuclear reactions, and I do not understand where your values come from.

    Thanks again for trying to help
  7. Jul 30, 2013 #6
    Its not right to use theta in thermal energy because in thermal area of energy scattering is isotropic!
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