Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Controlling Nuclear Fission Geometry

  1. Oct 16, 2013 #1
    Hi everyone,
    I'm an engineer and not a physicist, so forgive me if something sounds stupid.

    Question: Is it possible to know, which way products of nuclear fission (u-235) will go?

    Imagine a sheet of single (or few) atom layer crystal of U-235, that is irradiated by neutron source from the edge. Is it possible to predict where fission products will go?

    Is it better done experimentally or can be done theoretically or through simulation?
  2. jcsd
  3. Oct 17, 2013 #2
    No, they will go randomly in any possible direction
  4. Oct 18, 2013 #3
    Why? There are at least 2 factors that are not centrally symmetrical.
    One is the direction of the incoming neutron. And the other... Uranium 235 has odd number of nucleons, so it has to be a fermion. In fact, the spin happens to be 7/2... so even if the neutron happens to have opposite spin (which it would not always have) the result would be at least spin 3.

    Wouldn´t the centrifugal force favour the fission products going somewhere along the equator of the U-235 nucleus rather than towards its poles?
  5. Oct 18, 2013 #4


    User Avatar
    2017 Award

    Staff: Mentor

    Spin is not a rotation.
    There might be some dependence on the spin direction, but as you don't control that spin direction, this does not change the result.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook