I assume the above reaction is less energetically favorable than the creation of He-3 (plus a neutron) or tritium plus a proton? But why/how?

Or are the hard, hot, fast collisions too much for it to stay together?


1 Answer 1


For two particles to merge and become one, the incident momenta have to be exactly right. More technically, because there are no low-lying excitations, the phase space is small.

When they merge to two particles, many more input possibilities exist that can combine, because there are more possible energies for the two outgoing particles. That makes the reaction occur faster.

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    $\begingroup$ I’d just say you can’t conserve energy and momentum and be done with it. The volume in phase space of the perfect collision is really zero to a very high degree of accuracy. $\endgroup$
    – Jon Custer
    Commented Jun 15, 2019 at 21:26

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