 This occurs when photons from a Free-electron laser collide with accelerated Electrons, producing a beam of high energy photons with a very precise energy and a high degree of polarization.The gamma-ray beams can be produced with energies ranging from 1-100 MeV with a maximum intensity of 1000 formula_1/s/eV, making HIGS the highest intensity accelerator driven gamma-ray source in the world.Research at HIGS can be broken broadly into two groups