Upgraded back-end electronics for the CMS Fast Beam Conditions Monitor

In the CMS experiment, the Fast Beam Conditions Monitor (BCM1F) detector, located close to the Interaction Point, provides an online, bunch-by-bunch measurement of both Luminosity and Machine Induced Background. The Beam Pickup Transformer (BPTX) provides instead a precise measurement of beam intensity and arrival time. An upgraded back-end electronics has been developed for the BCM1F, based on the modern uTCA standard which has been adopted by several other CMS sub-systems. This system, which is slated to replace the current VME-based readout, will also be used to replace the BPTX readout, currently implemented with an oscilloscope-based system. The upgraded back-end is composed of FPGA carrier cards, developed by CERN, coupled to commercial mezzanine cards hosting high-performance digitizers. While the carrier card and most of the FPGA firmware is common, the digitizer and the signal processing algorithm is detector-specific. The main challenge for the BCM1f readout is ensuring the correct identification of all particle hits, even when multiple particles reach the detector in the same bunch crossing. A peak finder algorithm has been developed, capable of 10 ns double-hit resolution. The higher counting accuracy, compared to the legacy system, will allow a more precise measurement of Luminosity and discrimination of Machine Induced Background.The modular nature of this hardware and firmware will allow to extend this system to other detectors.