1. The problem statement, all variables and given/known data A beam of gamma rays of energy 1.00 MeV are aimed at a set of freely moving gold particles. The gamma rays reflected back have an energy of 0.2035 MeV. How is this result consistent with the model of a gamma ray reflecting from an isolated electron initially at rest? 2. Relevant equations E^2-P^2c^2=m^2c^4 3. The attempt at a solution I've tried a few ways using Compton scattering but to no avail. Determining the momentum of the gamma ray.