I recently asked this question: How close does a particle-antiparticle pair need to be for annihilation to happen?
And that received a good answer. But there was a second part to my question that was not addressed, and so I'm posting it here for more direct attention.
When an annihilation event occurs, how fast does it occur, and can the release of energy somehow be moderated (in a similar manner in which a fission reaction is moderated)? Or is it all or nothing?
With charged pairs I would think the task of moderating the reaction might be difficult since the two particles would be strongly attracted to one another. But then for a neutral particle pair (e.g. neutron and anti-neutron) there might be hope?