Particle Physics Seminar

To extend its physics reach, the Large Hadron Collider at CERN will be upgraded in 2024-2026 to deliver proton-proton collisions at 5-10 times higher luminosities than designed (HL-LHC). This will be a challenge for the ATLAS experiment that has to cope with higher particle densities, radiation and event pile-up of up to 200 interactions per bunch crossing. Apart from the planned exchange of the full inner tracker, a complete new detector is being proposed and developed to complement precise tracking with ultra-fast timing: the High Granularity Timing Detector (HGTD). It will exploit the fact that the primary vertices where the individual interactions take place are not only distributed in space, but also in time. Hence, measuring the time of each particle with about 30 ps precision allows to further suppress backgrounds from pile-up and restore the reconstruction performance of b-tagging, jets, isolated leptons and missing transverse energies, which is crucial for many physics analyses. The HGTD will cover a pseudo-rapidity range of 2.4 to 4.0 with a granularity of 1.3x1.3 mm2. It is only made possible by the rapid advance of a new silicon detector technology, namely Low Gain Avalanche Detectors (LGAD), which have been developed by CNM Barcelona and the CERN RD50 Collaboration and are now also produced by Hamamatsu, FBK, BNL and Micron. It has been shown that LGADs can fulfill the challenging HGTD requirements, especially also after the high radiation fluence levels expected at the end of life time of up to 5e15 neq/cm2.
This presentation will motivate and introduce the HGTD and present the new LGAD sensor technology including performance measurements before and after irradiation. New developments such as 4D-tracking and possible other applications inside and outside High Energy Physics (forward detectors like AFP, low-energy X-rays, radio-therapy) will be discussed as well.