The measurement of emittance in space-charge dominated, high brightness beam systems is investigated from conceptual, computational, and experimental viewpoints. As the self-field-induced collective motion in the low energy, high brightness beams emitted from photoinjector rf guns are more important in determining the macroscopic beam evolution than thermal spreads in transverse velocity; traditional methods for phase space diagnosis fail in these systems. We discuss the role of space charge forces in a traditional measurement of transverse emittance, the quadrupole scan. The mitigation of these effects by use of multislit- or pepper-pot-based techniques is explained. The results of a direct experimental comparison between quadrupole scanning and slit-based determination of the emittance of a 5 MeV high brightness electron beam are presented. These data are interpreted with the aid of both envelope and multiparticle simulation codes. It is shown that the ratio of the beam's beta function to its transverse plasma wavelength plays a central role in the quadrupole scan results. Methods of determining the presence of systematic errors in quadrupole scan data are discussed. /home/httpd/docserver/releases/20080613005430/public/paper/file/28/anderson_2002_0129.pdf anderson_2002_0129.pdf 1 28 Electron beamsParticle beam diagnosticsSpace chargeBeam handling, focusing, pulsing, stripping and diagnostics [A2925F], Beams in particle accelerators [A2921], Particle beam handling and diagnostics [B7410B]high brightness electron beam emittance measurement, space-charge dominated beam, self-field-induced collective motion, space charge forces, transverse emittance, multislit, pepper-pot, beta function APS, USA. English Journal Paper 0 2002 Physical Review Special Topics-Accelerators & Beams 129 2007-10-22T14:51:15-07:00 014201 2002