INFN Acceleratori

Why generate muon beams using X-ray photons? Advanced X-ray FELs are capable to achieve brilliances that outrun any other particle beam. Therefore the marriage between X-ray FELs and Energy Recovery Linacs (ERL) carries a potential to attain luminosity levels, in an electron-photon collider, that exceed 10⁴⁰ cm^-2 s^-1. We studied this new paradigm for muon beam generation, named EXMP (Electrons and X-rays to Muon Pairs), which shows potentials of performances compatible with the requests of muon colliders. In particular, since the primary collision (e-hν) occurs in vacuum, extremely high phase space densities can be achieved, with extremely small normalised emittances of the muon beam, down in the nm^.rad range, with average fluxes up to 10¹¹ muon pairs per second. A possible scenario for GeV muon beam generation, prompt acceleration to TeV energy range and power budget analysis is illustrated, underlying unique properties of the EXMP paradigm, like the capability to generate polarised muon beams.