The DCCT for the LHC Beam Intensity Measurement

The LHC circulating beam current measurement is provided by eight current transformers, i.e. two DC current transformers (DCCT) and two fast beam current transformers (FBCT) per ring. This paper presents the DCCT, designed and built at CERN, including the sensor, the electronics and the front-end instrumentation software. The more challenging requirements are the needed resolution of 1μA rms for a 1s average, and the wide dynamic range of the circulating beam intensity from a single pilot bunch (8μA) to the total ultimate beam current of 860mA. Another demanding condition is the high level of reliability and availability requested for the operation and for the machine protection of this highly complex accelerator. The measurement of the first RF captured beam in ring 2 will be shown to demonstrate that the system is close to meeting these specifications both in terms of resolution and stability.