Elena Orbit and Schottky Measurement System

A new Extra Low ENergy Antiproton ring (ELENA) is under construction at CERN to further decelerate the antiprotons from the existing Antiproton Decelerator (AD) to an energy of just 100 keV. This contribution will describe the beam position system foreseen for ELENA and how it can be adapted for Schottky measurements. The orbit system being developed is based on electrostatic shoe­box BPMs fitted with Digital Down Converters (DDC). The main requirement is to measure complete orbits every 20 ms with a resolution of 0.1 mm for intensities in the range of 1-3x107 charges. The pick-up signals will, after amplification with a low noise charge amplifier, be down-mixed to baseband for position computation. In order to provide the longitudinal Schottky diagnostics of unbunched beams, the 20 BPM sum signals will, after time off flight corrections, be added digitally to give an expected S/N increase of 13 dB compared to using a single electrostatic pick-up.