Before the discovery of the neutron, it was proposed that the penetrating radiation produced when beryllium was bombarded with alpha particles consisted of high-energy &gamma rays (up to 50 MeV) produced in reactions such as α + 9Be --> 13C + γ
a.) Calculate the Q value for this reaction.
b.) If 5-MeV alpha particles are incident on 9Be, calculate the energy of the 13C nucleus and, hence, determine the energy of gamma radiation assuming it is emitted as a single photon. Hint: You may neglect the momentum of the γ ray relative to the 13C nucleus. Masses: m(4He) = 4.0026u, m(9Be) = 9.0122u, m(13C) = 13.0034u
m(Z, N) = A*1u +Δ where the Δ stands for the mass excess and A = Z + N
Q = (mc + md - ma - mb)c2
The Attempt at a Solution
My main gripe with this problem is that i dont understand why we can neglect the momentum of the gamma ray when conserving momentum. I did the problem with the assumption but can the problem still be done without it?