Photon flux and spectrum of γ-raysγ-rays Compton sources

We analyze the characteristics of the γγ radiation produced by Compton back-scattering of a high brightness electron beam produced by a photoinjector and accelerated in a linac up to energies of 360–720 MeV and a laser operated at about 500 nm, by comparing classical and quantum models and codes. The interaction produces γγ rays in the range 4.9–18.8 MeV. In view of the application to nuclear resonance fluorescence a relative bandwidth of few 10−310−3 is needed. The bandwidth is reduced by taking advantage of the frequency–angular correlation typical of the phenomenon and selecting the radiation in an angle of tens of μradsμrads. The foreseen spectral density is 20–6 photons per eV in a single shot, a number that can be increased by developing multi-bunch techniques and laser recirculation. In this way a final value of 104104 photon per eV per second can be achieved.