Single shot transverse emittance measurement of multi-MeV electron beams using a long pepper-pot

We present a pepper-pot design in which we address the problem of penetration by high energy particle, deriving analytical expressions and performing GEANT4 simulations for the estimation of the error introduced by a long (thick) pepper-pot. We also show that a careful design allows to measure the emittance of electron beam of several hundreds MeV and beyond.