Proposal for instrumentation to calibrate DCCT's up to 24 kA

The zero flux DC Current Transformer (DCCT) originated in CERN about 25 years ago. It was developed as an instrument to measure beam currents, but the potential applications of measuring and regulating the electric currents in beam transport magnets are already mentioned in the first publications. The development work in CERN was always limited to beam instrumentation, with priorities on high resolution, fast response and large dynamic range. Beam currents covered the range from μA to 60 A. Beam lifetime measurements required a resolution of a few ppm (parts per million). This technology has many potential applications and is specially interesting for very high precision current measurements in the standards laboratories. Beam current monitors, developed at CERN in 1981 and again in 1990, became national primary standards in Germany, certified and operated by the PTB in Berlin. This note makes use of the existing know-how to present a new solution for precision current measurements in the SL-PC standards laboratory, with full scale ranges from 12 mA to 24 kA. The same technique could later be used to control the magnet currents in the LHC.