Beam Position Monitors for the Fermilab Recycler Ring

Fermilab’s new Recycler Ring will recover and cool “used” antiprotons at the end of a Tevatron store and also accumulate “new” antiprotons from the antiproton source. A wideband rf system based on barrier buckets will result in unbunched beam, grouped in one to three separate partitions throughout the ring. A new beam position monitor system will measure position of any one partition at a time, using low-frequency signals from beam distribution edges. A signal path including an elliptical split-plate detector, radiation-resistant tunnel preamplifiers, and logarithmic amplifiers, will result in a held output voltage nearly proportional to position. The results will be digitized using Industry Pack technology and a Motorola MVME162 processor board. The data acquisition subsystem, including digitization and timing for 80 position channels, will occupy two VME slots. System design will be described, with some additional emphasis on the use of logamp chips.