Full Inverse Compton Scattering: 255.5 keV photons can stop “any” relativistic electron

by Luca Serafini (INFN-Milan/LASA and University of Milan, Department of Physics)

IFIN-HH/ELI-NP Training and Conference Center

IFIN-HH/ELI-NP Training and Conference Center


Collisional radiation sources are those based on electron-(real) photon interactions, whose main paradigm is represented by Inverse Compton Scattering X and Gamma ray sources. Complementary to undulatory radiation sources, whose main paradigms are Synchrotron light sources and FELs. Although the first interest in inverse Thomson or Compton scattering arised in the ‘40s around the atomic bomb development and in the just born astro-physical community, real experiments with lasers and particle accelerators were conducted only in the ’60s. But in order to achieve X and Gamma ray photon beams of interest to users, with adequate performances of brilliance, fluxes and spectral densities, we had to wait until almost 15 years ago for the mature development of two enabling technologies: CPA lasers and high brightness photo-injectors. They allowed to boost the achievable luminosity of electron-photon colliders (as Inverse Thomson/Compton scattering sources are) by orders of magnitude, and they opened the era of ICS devoted to user facilities like STAR, serving advanced radiological imaging applications (with micro-tomography), nuclear photonics and photo-nuclear physics, and, more upfront, secondary beam sources of low emittance muon and positron beams. As a latest development, recent studies of extreme Inverse Compton scattering showed possible new regimes of interactions where the total transfer of energy/momentum from the electron to the scattered photon can be achieved, opening new opportunities of spectral purification effects and full stopping of relativistic electrons in vacuum, possibly impacting the world of cosmic Gamma-ray sources and possibly enabling the generation of quantum gravitational effects.