• D. B. Belohrad, O.R. Jones, M. Ludwig, J.-J. Savioz, S. Thoulet
  CERN, Geneva

The fast beam intensity measurements for the LHC are provided by eight Fast Beam Current Transformers (FBCT). Four FBCTs installed in the LHC rings are capable of providing both bunch-by-bunch and total turn-by-turn beam intensity information. A further four FBCTs, two in each of the LHC dump lines, are used to measure the total extracted beam intensity. In addition to providing intensity information the ring FBCTs also send signals to the machine protection system. This increases the complexity of both the RF front-end and the digital acquisition parts of the signal processing chain. The aim of this paper is to discuss the implemented hardware solution for the FBCT system, in particular with respect to the signal distribution, FPGA signal processing, calibration, and interaction of the FBCTs with the machine protection chain.

• OP. Odier, M. Ludwig, S. Thoulet
  CERN, Geneva

The LHC circulating beam current measurement is provided by 8 current transformers, i.e. 2 DC current transformers (DCCT) and 2 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 the order of 1μA rms at 1s average, and the wide dynamic range of the circulating beam intensity from the pilot bunch (8μA) to the ultimate beam (860mA). Another demanding condition is the high level of reliability and availability requested for the operation and machine protection of this highly complex accelerator. The measurement of the first RF captured beam in ring 2 is close to meet the specifications in term of resolution (1.3μA rms at 1s average) and stability over a period of a few hours (drift less than 3μA). Finally elements intended to be installed in the near future are presented.