I wrote: I'm guessing that all of these reactions are only energetic if the pion > exchange occurs simultaneously with the decay to lighter daughters, as is > being modeled here. >
This turns out not to have been true. A followup check indicated that there were several reactions in the earlier list in which there was no subsequent decay to lighter daughters, and yet the pion exchange ended up producing an exothermic reaction. Note also the resulting Q values, which range from 76 keV to 1.6 MeV, which is very nice in terms of limiting radiation from fast daughters. Eric
