Why does Uranium-238 absorb fast moving neutrons

  • Thread starter Ed Aboud
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  • #1
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Main Question or Discussion Point

Hi all.
Why does Uranium-238 absorb fast moving neutrons very well but not slow moving ones?
My intuition tells me it should be the other way around but its not.
Thanks.
 

Answers and Replies

  • #3
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Hmm, I still don't really get it.
 
  • #4
vanesch
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U-238 captures slow neutrons as well as fast, and even a bit more slow than fast. However, U-235 fissions MUCH MORE easily with slow neutrons than with fast, and hence the ratio for fission in U-235 over capture in U-238 is more favorable for slow neutrons than for fast.
 
  • #5
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Oh ok, I get it now. Thanks very much.
 
  • #6
malawi_glenn
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it has to with the pairing force, the answer vanesh gave you.
 

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