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Is it possible to have neutron capture reaction induced by more than one neutron?

I mean X(2n,...)Y.

I think i saw some reactions like that before but cant remember the source. Thanks

Don el Fuego Integer
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    Yes. The r-process (r stands for rapid, I believe) in stellar nucleosynthesis does that. – CuriousOne Sep 07 '15 at 06:39
  • Thank You for the response. I remember you mentioned R-process in my previous question. Well, I was thinking more from nuclear physics side. Im trying to find out if nuclear fuel could bild up not only by +1 neutron but more. I want to believe nuclear flux is too low, and more likely one nucleus will be captured by other surrounded fuel atoms. – Don el Fuego Integer Sep 07 '15 at 06:53
  • If I had to take a gut shot at it, I would assume that such processes are quite plausible inside a nuclear weapon if you insist on them taking place in a very short time scale (on the order of a few ns). Apart from that, of course, there is no reason to dismiss neutron capture cascades on timescales that will allow the intermediate nuclei to shed energy e.g. in form of gamma rays. I am not a nuclear physicist, though, so I can't tell you any particularly important case of the top of my head. – CuriousOne Sep 07 '15 at 07:00

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A three-body capture, $$ ^AZ + \mathrm{n+n} \to {}^{A+2}{Z} + \gamma $$ is exceedingly unlikely because it is essentially impossible for three bodies to converge at the same place.

However, sequential captures \begin{align} ^AZ + \mathrm n &\to {}^{A+1}Z \\ ^{A+1}Z + \mathrm n &\to {}^{A+2}Z \\ \end{align} can happen any time the neutron flux is high enough that the second interaction can take place before the nuclide $^{A+1}Z$ decays. You could have this happen in nuclear reactors (some of which are designed for this purpose), in nuclear explosions, and in the r-process of supernova collapse.

rob
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