Production and Quality Assurance of a Scintillating Fibre Detector for the LHCb Experiment

At the Large Hadron Collider (LHC) at CERN, scientists from around the world are using complex detector systems to test the predictions of the Standard Model and to search for indications of new physics. One of those detectors is the LHCb experiment which was specifically designed for the study of heavy hadrons containing bottom and charm quarks (heavy flavour physics). To deal with the increased beam energy and instantaneous luminosity of the LHC after the Long Shutdown 2 in 2018/19, several subsystems of the LHCb detector have to be exchanged and upgraded. For this purpose, a new tracking system that will replace the so-called Inner and Outer Tracker of the current detector is currently being developed and built. The base of this new tracker are 2:5m long scintillating fibres ($\varnothing 250 \mu$) into which light is induced by passing charged particles. The fibres are arranged in six-layered fibre mats which are read out with the help of silicon photomultipliers at the edge of the tracker’s acceptance. The finished tracker will have a spatial resolution below 100 $\mu$ and will cover an area larger than 360m2. To produce the required total of 1100 fibre mats until the beginning of the second Long Shutdown, mass production must be set up at several locations. To assure the quality of the fibre mats, they are subjected to various tests during the production. One of those is a check of the integrity of the fibre matrix inside the mats which is used to look for irregularities and defects. Furthermore, different properties such as light yield, attenuation length, spatial resolution, and detection efficiency are measured with the help of another setup as well as beam tests at carried out at CERN. In this talk, the various studies of the fibre mats are explained in detail and first results are presented.