1. The problem statement, all variables and given/known data Hi, I'm trying to find out the formulae that gives me the threshold energy for a nuclear reaction (i.e. The minimum amount of energy required to induce a reaction). I've got a question which states an endothermic reaction of : O + p --> F + n has a Q value of -2.45 MeV. Given that the atomic masses of O is 17.99916 u, neutron mass is 1.008665 u and proton mass is 1.007276 u, find the atomic mass of F. I got this to be 18.00040 Second part says If the Oxygen (i.e. O) is at rest before the reaction, what is the threshold energy for the reaction. I used : [(-m_F + m_n)/m_F + m_n - m_p) ] Q = Threshold energy Finally, third part says a proton is incident on an oxygen nucleus at rest, The neutron from the reaction is emitted at 90 to the incident beam. How can I calculate the energy of the incident proton? Thanks very much.