Past exam of the MPhil in nuclear energy course of the University of Cambridge / 2021 / Module NE1 / 1 / a / Solution

The lighter product receives the fraction $1/(1+m/M)$ of the two massive products' kinetic energy. Neglecting photon momentum, conservation of momentum gives equal and opposite daughter momenta, ${\mathbf{p}}_m=-{\mathbf{p}}_M$. In the nonrelativistic approximation,Hence $K_{\mathrm{products}}=K_m(1+m/M)$ andThis partitions kinetic energy after any stipulated photon energy has been removed from the available Q value. It does not assign the complete mass-defect energy to the light particle.