A Beam Position Monitor System for the Proton Storage Ring at LAMPF

A high-current Proton Storage Ring (PSR) is being constructed at Los Alamos to accumulate intense pulses of 800-MeV protons from LAMPF for delivery to neutron production targets. The beam´s transverse location in the injection channel, ring, and extraction channel will be determined by a beam position monitor (BPM) system. The beam will be detected by stripline sensors that generate 4-quadrant position signals from the spectral components of the beam. Sixty sensors are planned for the installation, with their outputs selected by broadband RF multiplexers. The sensor outputs are processed by a differential phase correlator detector to produce an analog signal proportional to the position of the beam centroid. Digital conversion and processing will give overall resolution of the horizontal and vertical position of the beam at each sensor location to ±2 mm. The monitor will operate over the intensity range of 3 × 108 protons/ bunch to 5 × 1013 protons/bunch. The beam-position system contains CAMAC-based instrumentation for display in three formats, including an azimuth histogram, a time plot, and a numerical readout. The monitor system also includes a microprocessor-based check and exerciser unit to serve as a design aid and maintenance tool.