Prototype of an Integrating Current Transformer for Beam Intensity Measurements in the Large Hadron Collider

The beam intensity (number of particles forming the beam) in the Large Hadron Collider (LHC) is measured by eight current transformers. The average beam current is monitored by the four DC Current Transformers (DCCTs) and the range from a few hundred hertz to over a gigahertz is covered by the four Fast Beam Current Transformers (FBCTs). During the early run of the LHC the beam intensity measured by the FBCTs was observed to be correlated to the beam position and charge distribution. To address the consequential limitations a prototype of an Integrating Current Transformer (ICT) has been developed at CERN as a possible future replacement of the FBCTs. In this article, its design, principle of operation along with results of first beam tests are presented. The measured beam-position-dependency of the ICT has been improved, compared to the FBCT, by a factor of 35 and 50 in the vertical and horizontal planes, respectively.