A beam of 6.61MeV protons is incident on a tanget of 2713Al. Those that collide produce the reaction p + 2713Al ---> 2714Si + n (2714Si has a mass of 26.986721amu.) Neglect any recoil of the product nucleous and determine the kinetic energy of the emerging neutrons. Okay, what the heck is the idea here? I tried conserving the mass and the energy. What am I missing? The correct answer should be 1.00MeV, I get a number much bigger than that.