  We present the results of multi-objective genetic algorithm optimizations of
a potential single shot ultra fast electron diffraction beamline utilizing a
225 kV dc gun with a novel cryocooled photocathode system and buncher cavity.
Optimizations of the transverse projected emittance as a function of bunch
charge are presented and discussed in terms of the scaling laws derived in the
charge saturation limit. Additionally, optimization of the transverse coherence
length as a function of final rms bunch length at sample location have been
performed for three different sample radii: 50, 100, 200 microns, for two final
bunch charges: 100k and 1000k electrons. Analysis of the solutions is
discussed, as are the effects of disorder induced heating. In particular, a
coherence length per rms spot size of 0.27 nm/micron was obtained for a final
bunch charge of 100k electrons and final rms bunch length of approximately 100
fs. For a final charge of 1000k electrons the cryogun produces a coherence
length per rms spot size of 0.1 nm/micron for an rms bunch length of 100-200 fs
and final spot size of 50 micron. These results demonstrate the viability of
using genetic algorithms in the design and operation of ultrafast electron
diffraction beamlines.
