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

Radiocarbon creation mechanisms

  1. Apr 3, 2009 #1
    Hello all!

    I have a question about the way or ways in which C-14 can be created:

    From the background research I have done, I see that high energy neutrons colliding with nitrogen atoms give rise to C-14. I also looked a little bit into beta+ decay. I was curious as to whether or not beta+ decay could also create radiocarbon?

    From what I'm able to gather, nuclear testing also created C-14 from nitrogen. I was curious if the energy released by the nuclear detonation alone created the C-14 or if the presence of free neutrons in the atomic blast was necessary for C-14 creation?
  2. jcsd
  3. Apr 4, 2009 #2
    C-14 production from beta plus decay would happen from nitrogen-14, which is a stable nucleus, so C-14 won't be produced by beta + decay, at least not directly by it.

    In nuclear detonations, the neutrons are necessary to induce the
    n + N-14 --> C-12 + H-1
    reaction. If you had a neutron-free nuclear weapon, whose energy would be released only by charged particles and medium-energy photons (primarily x-rays), C-14 would not be produced, nor any other nuclear reaction would take place outside the weapon.
    Last edited: Apr 4, 2009
  4. Apr 4, 2009 #3
    Right on. So the presence of free, high-energy neutrons is absolutely necessary for the nuclear reaction which creates C-14 then?

    I was thinking that meteor impacts such as the siberian impact in 1908 which released 15 megatons of energy could create C-14, but I guess in lieu of free neutrons in the blast, that would not occur?
  5. Apr 5, 2009 #4
    Yep, the neutrons are necessary. Meteor impacts, even when on such a large scale, release the energy in a different way and no free neutrons are emitted. In an impact event, the kinetic energy of the meteorite is converted to heat. It might look like a nuclear explosion and have same magnitude of energy release, but would not actually change any nuclei, and as such, not release any neutrons.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook