A high power Faraday cup to measure extracted beam current from the Bates South Hall Ring

A water-cooled Faraday cup has been installed at the Bates Linear Accelerator Center in order to measure the extracted beam current from the pulse-stretcher ring in the South Experimental Hall. The Faraday cup is designed to dissipate 100 kW of heat and is thus well-matched to the beam characteristics of Bates (50 /spl mu/A at 1 GeV). The device has been placed on a cart-and-rail system so that it can be remotely driven into and out of the beam line. We expect the Faraday cup to serve as an absolute calibration source for beam current measurements to better than 0.1% accuracy. This will allow for very high precision cross section measurements and the isolation of small interference response functions with reduced systematic uncertainty.