A Quantal, Partially Ordered Electron Structure as a Basis for a \gamma   Free Electron Laser (\gamma-FEL)
  When a rather cold electron bunch is transported during laser bubble acceleration in a strongly focusing plasma channel with typical forces of 100 GeV/m, it will form partially ordered long electron cylinders due to the relativistically longitudinal reduced repulsion between electrons, resulting in a long-range pair correlation function, when reaching energies in the laboratory above 0.5 GeV. During Compton back-scattering with a second laser, injected opposite to the electron bunch, the electron bunch will be further modulated with micro bunches and due to its ordered structure will reflect coherently, M\"ossbauer-like, resulting in a \gamma free electron laser (\gamma-FEL). Increasing the relativistic \gamma factor, the quantal regime becomes more dominant. We discuss the scaling laws with \gamma. 
D. Habs, M. M. G\"unther, S. Karsch, P. G. Thirolf and M. Jentschel
physics.acc-ph physics.plasm-ph