Development of the Readout Electronics for the Beam Loss Monitors of the LHC

The Large Hadron Collider (LHC) of the European Laboratory for Particle Physics will be the largest particle accelerator in the world. It requires a large number of installations for its operation. One of these installations are the beam loss monitors which measure the particle losses. If these losses exceed a certain level, the beam must be extracted, otherwise the superconducting magnets could be damaged. For this reason, ionization chambers are installed outside the cryostat to transform the losses into an electric current. A wide dynamic range front end was developed to measure this current. The circuit consists of a current-to-frequency converter that works on the principle of balanced charge. Its output frequency is evaluated by counters and the data is serially transmitted from the tunnel to the surface, where the final data processing is performed. The data transmission suffers from the long cabling distance of up to 2 km. Using Manchester Code and line equalizers enables a data rate of 2 Mbit/s over a common twisted pair cable. This transmission problems lead to a detailed analysis of transmission lines in the frequency and time domain.