Multi-Processor based Fast Data Acquisition for a Free Electron Laser and Experiments

FLASH (Free electron LASer in Hamburg) at DESY is a user facility with laser-like radiation source in the VUV and soft X-ray range. It is also a pilot facility for the future XFEL. A fast data acquisition system to support the accelerator operation and the user experiments was developed. The system collects data from hundreds of ADC channels in the range of 1M up to 2G samples per second. In addition it allows collecting images from digital video cameras. All the data are collected in a shared memory of a central multi-processor computer. Several processes are used to calculate e.g. the orbit, energy or photon flux, or are used as feedback loops to improve the stability of the linac. A long time archiving of the collected data from the accelerator and from the FEL experiments on a 24 TB disk and finally on a tape is provided. The whole system is integrated in the DOOCS control system of FLASH.