Electron Beam Optimization for a High-Brightness Gamma-Ray Source*

Compton-Scattering based systems offer a path to high-brightness high-energy ($>$ 1 MeV) x-ray \& gamma-ray sources due to their favorable scaling with electron energy. LLNL is currently engaged in an effort to build such a device, dubbed the ``Thomson-Radiated Extreme X-Ray'' (T-REX) source. Presented here is an overview of the system design, which includes both a UV-laser-driven electron photoinjector and an intense scattering laser. Also shown are the results of detailed electron beam and gamma-ray generation modeling designed to optimize the brightness and flux of the gamma-ray beam, including UV drive laser profile effects, charge v. emittance tradeoffs, thermal emittance effects, and contributions of focusing geometry.