  A comparison of the two most prominent electron sources of high average
current high brightness electron beams, DC and superconducting RF photoemission
guns, is carried out using a large-scale multivariate genetic optimizer
interfaced with space charge simulation codes. The gun geometry for each case
is varied concurrently with laser pulse shape and parameters of the downstream
beamline elements of the photoinjector to obtain minimum emittance as a
function of bunch charge. Realistic constraints are imposed on maximum field
values for the two gun types. The SRF and DC gun emittances and beam envelopes
are compared for various values of photocathode thermal emittance. The
performance of the two systems is found to be largely comparable provided low
intrinsic emittance photocathodes can be employed.
