A 3.9 MeV photoinjector and delay system for Wakefield measurements

Abstract

We report on the characterization of the 3.9 MeV electron beam from a rf photoinjector at the Argonne Wakefield Accelerator. This beam is used to diagnose wakefields produced by the 15 MeV beam from a second rf photoinjector. We measured the emittance with the usual quadrupole scan method but used a fitting algorithm that includes space-charge forces. This photocathode gun has produced a beam charge per pulse ranging from 10 pC to 4 nC, but is normally operated at 100 pC with a measured normalized emittance of 3.4 π mm mrad and bunch length of 8 ps full width at half maximum.