DELTA beam position monitor

For the electron storage ring DELTA (Dortmund Electron Test Accelerator) a beam-position-monitor (BPM) system based on button pickups has been designed. Two different concepts for the monitor electronics have been developed, and they yield a long-term stability better than +or-150 mu m and a short-term resolution below +or-10 mu m. There are no hybrids integrated in the electronic circuits, as all four button signals should be amplified and digitized to provide redundancy. First, a concept using four separated electronic branches, one for each button, was tested. Then, a concept with a multiplexer in front followed by only one amplifier was designed. This concept, the electronic circuits, and the measurements are presented. >