BEAM-SIZE MEASUREMENTS IN THE IPNS 50-MeV TRANSPORT LINE USING STRIPLINE BPMS

Continuing with the work started two years ago, the technique of using a two-beamlet model to measure beam size is presented(1). Beam signals are detected on terminated 50-Ω, stripline BPMs located in the transport line between the 50 MeV linac and rapid cycling synchrotron. Each BPM is constructed with four striplines: top, bottom, left and right. Using a fast- sampling oscilloscope to compare the signals from opposite strip lines allows one to determine beam size assuming a two beamlet model. Measurements made with the two-beamlet approach are compared with other standard profile diagnostics such as wire-scanners, segmented Faraday cups, and scintillators. Advantages of the two-beamlet method are that it is non intrusive and does not require the presence of a background gas necessary for an IPM. Disadvantages of the technique are that it does not provide a detailed profile and the longitudinal beam pulse length must be short relative to the stripline length.