Challenges in plasma and laser wakefield accelerated beams diagnostic

The new frontier in the particle beam accelerator is the so called plasma acceleration. Using the strong electric eld inside a plasma is possible to achieve accelerating gradients order of magnitude larger with respect to the actual technologies. Di erent schemes have been proposed and several already tested, producing beams of energy of several GeV. Mainly two approaches are followed: either the beam is directly produced by the interaction of a TW/PW class laser with a gas jet, or a preexisting particle beam is accelerated in a plasma channel. In both cases a precise determination of the emerging beam parameters is mandatory for the ne tuning of the devices. The measurement of these parameters, in particular the emittance, is not trivial, mainly due to the large energy spread and to the tight focusing of these beams or to the background noise produced in the plasma channel. We show the problems related to the diagnostic of this kind of beams and the proposed or already realized solutions.