ALICE FIT detector

Fast Interaction Trigger (FIT) is being designed and constructed to replace the current T0, V0, and FMD detectors during the upgrade of ALICE in 2019-2020. The work on FIT involves about 50 scientists, engineers, and students from 14 institutes in 6 countries. Our group was awarded the leadership of this project. FIT will be a key element in the operation of the upgraded ALICE. The main online functionalities of FIT will be luminosity monitoring with a direct link to the LHC and generation of fast trigger signals for the ALICE subsystems. The trigger generated by FIT will allow for online vertex determination, minimum bias and centrality-based event selection, suppression of beam-gas events, and a veto for ultra peripheral collisions. The trigger will be generated with the latency of less than 425 ns including a 222 ns delay along the connecting cables. For the offline analysis FIT will provide the precise collision time for the Time-of-Flight (TOF) based particle identification and unbiased multiplicity distribution in the forward direction. The latter is needed for the determination of the centrality and of the event plane in heavy-ion collisions.

In 2017 FIT successfully completed three Engineering Design Revives and two rounds of in-beam tests. We have also finalized the modification of the MCP-PMT based photo-sensors. The mockup of the Cherenkov array was produced and integrated with other upgrade elements. The first concept of the mechanical support for the large scintillator ring was recently completed and approved by the technical coordination of the ALICE experiment.