Modifications of the LCLS Photoinjector Beamline

The LCLS Photoinjector beamline is now in the Design and Engineering stage. The fabrication and installation of this beamline is scheduled for the summer 2006. The Photoinjector will deliver 10 ps long electron bunches of 1nC with a normalized transverse emittance of less than 1 mm.mrad for 80% of the slices constituting the core of the bunch at 135 MeV. The calculations done to finalize the specifications of the photoinjector beamline components are described. Modifications include a new exit energy, additional focusing between the two linac modules, the insertion of a ''laser heater'', and a new geometry for the coupling cells of the RF structures. We also discuss two interesting tunings, one for the nominal charge of 1nC but using a longer laser pulse and the second one for a lower charge of 0.2nC. Sensitivity to field errors and misalignment for those two new configurations is compared to that of the nominal tuning