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A Beam Position Monitor (BPM) using Virtex II pro FPGAs (‘Libera Electron’ from Instrumentation Technologies) has been programmed with an alternative firmware in order to determine the charge by measuring integrated RF amplitude, over an adjustable time window, of signals from 4 strip lines. These strip lines are located on the transfer line from the linac to the booster, on the booster ring, on the transfer line from the booster to the storage ring and on the storage ring. By calibrating the RF loss in all the cables, knowing the geometry of the strip lines and using the crossbar switching before the 4 RF ADCs of the Libera, the charge/current can be compared in order to determine the efficiency of transfer at various locations during injection. Since the current in the storage ring is known to a high accuracy using a parametric current transformer (from Bergoz Instrumentation), the absolute charge can be determined at all locations.
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