Prof. Mattioli was one of the main supporter of the idea of creating an FEL-Accelerator group at the Physics Department of the University of Rome "La Sapienza" in the context of the SPARC/X collaboration. The group would attract students and constitute an important link between the Frascati Laboratories where the machine is going to be build and the always evolving university world.

The group was build around this idea, putting together expertise coming from different areas. That created an interested melting pot of research activities. All the different system of the SPARC machine are here represented in some part and the group has a comprehensive view-from-the-top of the project as a whole, a necessary ingredient in complex projects where many sub-systems have to work together. Ranging from the development of the photocathode laser and the study of pulse-shaping technique to x-ray optics, going through the diagnostics and control systems, with expertise in RF and synchronization issues, this mostly young group is finding its special place in the SPARC collaboration. Principal theoretical interests of the group members are the different kinds of interaction between the relativistic electrons and the laser beams. Non-linearity of FEL dynamics, seeding of FELs, higher harmonic generation, Inverse Compton scattering, laser accelerators are all part of this extended family of problems.