By Cosylab
For the for the ELI-NP GBS project, Cosylab developed device integration for several types and classes of devices. An example of our proactive approach to control system integration was the case of integrating a Fast Digitizer into EPICS for GBS Beam Charge Monitoring. For Big-Physics facilities with unique systems requirements, such as the ELI-NP GBS, commercial off-the-shelf technology is rarely good enough. Instead, cutting-edge hardware with custom integration is the only way to go. While any custom device integration has its own individual challenges, an excellent example of a demanding device integration into EPICS for the project at hand was an ADC to digitize the output of the integrating current transformer (ICT). An ICT, as opposed to more standard beam charge monitors, was needed because of the nature of the GBS electron beam. The latter has an electron train of 32 micro-bunches at a rate of 100 Hz. Each micro-bunch is 50 ps wide and is 16 ns apart. This meant that an ADC with a sufficiently high sampling rate was needed for accurate measurement. The Consortium demanded a multi-GS/s sampling rate, a wide input-voltage signal-range of 0-10 V and compatibility with the CompactPCI platform. We chose an Agilent High-Speed Digitizing Scope with a real-time sampling rate of up to 4 GS/s. In addition, the acquisition of the signal was synchronized with the timing signal (100 Hz) with low jitter in the order of magnitude of several picoseconds. The goal of the integration was to provide a way to operate the Digitizing Scope from EPICS, as part of the overall control system. Therefore, we delivered the necessary EPICS device support to interface between the hardware-specific fields in an EPICS database record and the device drivers/hardware.
