Beam phase and intensity monitor (BPIM) for the LHCb Experiment

The LHC bunch clock is transmitted over kilometres of fibre to the experiments where it is distributed to thousands of front-end electronics boards. In order to ensure that the detector signals are sampled properly, its long-term stability with respect to the bunch arrival times must be monitored with a precision of <100ps. In addition it is important to monitor the trigger conditions by measuring the intensity of each bunch locally in the experiment. For this purpose, we propose a beam phase and intensity acquisition board (BPIM) for the Button Electrode Beam Pick-ups which will be installed on both sides of the LHCb interaction point. The board measures the two quantities per bunch, and processes the information in an onboard FPGA. The information is read-out by the Experiment Control System and is directly fed to the LHCb Timing and Fast Control (TFC) [1]. In the TFC system the information is included in an event data bank but may also be used as a bunch crossing trigger or gate.