LHCb SciFi — Upgrading LHCb with a scintillating fibre tracker

LHCb will undergo a major upgrade during the LHC long shutdown 2 in 2019/2020 to cope with increased instantaneous luminosities and to implement a trigger-less 40 MHz readout. The current inner and outer tracking detectors will be replaced by a single homogeneous detector based on plastic scintillating fibres (SciFi). The SciFi tracker covers an area of 340 m$^2$ by using more than 10,000 km of scintillating fibre with 250 μm diameter, enabling a spatial resolution of better than 100μm for charged particles. Linear arrays of Silicon Photomultipliers cooled to −40°C are placed at the fibre ends. The readout of 524 k channels occurs through custom-designed front-end electronics. The assembly of the detector has started and the project is on track for installation starting end 2019. In view of future upgrades, a R&D; programme aiming at the development of very fast and efficient scintillating fibres, based on a novel type of luminophores (NOL), has been launched in parallel to the SciFi production. The performance of the prototype NOL fibres is competitive, in particular the decay time constant is close to 1 ns, i.e. about 50% shorter than the best standard fibre.