Speaker
Description
Fully integrated digital readout, pulse analysis, extraction of time and charge, signal alignment, multiplicity analysis and trigger generation electronics have been developed for the new Cherenkov-based Fast Interaction Trigger (FIT) for the upgrade of the ALICE detector at LHC,CERN. FIT will also serve as the main luminometer, collision time, multiplicity, centrality, and reaction plane detector for the ALICE experiment during Runs 3 and 4. The main sensor will be Planacon XP85012/FIT-Q – a modified MCP-PMT with a pore size 25 um. Among the many challenges of this project are a high dynamic range (1:500), requirement to operate with the sustained bunch crossing of 25 ns, provide time resolution below 50 ps, complete the entire signal processing and trigger generation within 205 ns, etc. To ensure proper operation over the required running time, a very low output amplitude of 10 mV/MIP at the detector output will be used, requiring special cabling and low-noise fast electronics. Event time will be evaluated by a CFD and then digitized with an accuracy better than 50 ps over the entire dynamic range. The input charge will be integrated and measured by an ADC. The digitized event data will be sent to the Common Readout Unit (CRU) by 4.8 Gbps optical links. Trigger data processing will be done in the two-level FPGA processor, based on the Kintex-7 Xilinx FPGAs with a 320 MHz main processing clock and a 600 MHz timing input clock. In total, FIT electronics will be processing 256 independent channels in parallel. The project has already completed and passed the Engineering Design Review. The prototype testing has been completed and the 205 ns total processing time was confirmed. The first prototype of the sensor and the front-end electronics have been installed inside of the ALICE magnet and were used to collect data from LHC collisions since 2016.
