Status of the APEX Project at LBNL

The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory is focused on the development of a high-brightness high-repetition rate (MHz-class) electron injector for X-ray FEL applications. The injector is based on a new concept gun, utilizing a normal conducting 186 MHz RF cavity operating in CW mode in conjunction with high quantum efficiency photocathodes capable of delivering the required repetition rates with available laser technology. The APEX activities are staged in 3 main phases. In Phases 0 and I, the gun is tested at its nominal energy of 750 keV and several different photocathodes are tested at full repetition rate. In Phase II, a pulsed linac is added for accelerating the beam at several tens of MeV to reduce space charge effects and measure the high-brightness performance of the gun when integrated in an injector scheme. At Phase II energies, the radiation shielding configuration of the bunker where APEX is located limits the repetition rate to a maximum of several Hz. Phase 0 is under commissioning, Phase I components under fabrication, and initial activities for Phase II are underway. This paper presents an update on the status of all these activities.Director of the Office of Science of the US Department of EnergyContract no. DEAC02-05CH1123