Photocathode Preparation System for the ALICE Photoinjector Available to Purchase

ALICE—Accelerators and Lasers in Combined Experiments—is a relatively new accelerator built at Daresbury Laboratory that will demonstrate the process of energy recovery by the end of 2008. The project is a research facility to develop the technology required to build a New Light Source (NLS) in the UK. This paper details the current ALICE photoinjector design and highlights the limitations before focusing on a photoinjector upgrade. The key component of the upgrade is a three‐stage extreme high vacuum load‐lock system that will be incorporated into the ALICE photoinjector in 2010. The load‐lock system has de facto become a standard component of a type III–V semiconductor photocathode injector and comprises: 1) loading chamber to allow new photocathodes to be introduced, 2) cleaning chamber for atomic hydrogen cleaning of the photocathodes and, 3) a preparation and activation chamber where the photocathodes will be activated to the NEA state ready for use on the ALICE accelerator. Once commissioned the load‐lock system will allow rapid transfer of photocathodes between the load‐lock system and the ALICE photoinjector whilst maintaining the integrity of the vacuum system and providing many other benefits. The new load‐lock system will not only remove the problems with the existing set‐up, it will also permit a new vacuum chamber to be designed for the gun itself. This new design will also aim to improve vacuum performance by addressing some of the major vacuum associated problems ALICE has encountered in the past 2 years.