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A point source isotropically emitting 10^8 fast nuetrons

  1. Aug 30, 2016 #1
    1. The problem statement, all variables and given/known data
    A point source isotropically emitting 10^8 fast nuetrons per second falls out of its shield onto a railroad platform 3 m horizontally from the track. A train goes by at 60 mph. Ignoring scattering and attenuation, what is the fluence of nuetrons that would strike a passenger at the same height above the track as the source?

    2. Relevant equation

    3. The attempt at a solution
    I know you need to write the distance to the train as a function of velocity and time. This can be done by having r^2=9+v^2*t^2. If the person in exactly across from the point source at t=0. I know I need to integrate this equation over some dt from -infinity to infinity but I'm confused as to what integral this goes into.
  2. jcsd
  3. Aug 31, 2016 #2


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    Maybe you can consider the passenger moving radially away from the point source?
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