Monolithic Picosecond Silicon Pixel Sensors for Future Physics: Experiments and Applications

Particle-physics, space research and several other fields of basic and applied science necessitate the production of large area detectors made by a new generation of thin sensors able to provide, at the same time, excellent position and time resolution. In the case of high-energy physics experiments, for example, with the advent of the very large number of collisions per bunch crossing foreseen at the High-Luminosity Large Hadron Collider (HL-LHC) (HL-LHC) and at the future Future Circular Collider (FCC), the density of particles close to the interaction point due to the pileup of events will be so high that efficient pattern-recognition and track-reconstruction will not be possible without precise timing information. At the HL-LHC, 4D event reconstruction will be achieved by two different detectors, specialised either in space or in time measurement. This expensive and complex solution will not be sustainable beyond the HL-LHC. Monolithic Active Pixel Sensors (MAPS) [1], which contain the sensor in the same CMOS substrate utilized for the electronics, might provide a viable solution. MAPS are particularly appealing since they offer all the advantages of an industrial standard processing, avoiding the production complexity and high cost of the bump-bonded hybrid pixel sensors that are commonly used in high-energy physics. MAPS are used in STAR, Mu3e and in the ALICE tracker upgrade and were proposed for the ATLAS HL-LHC pixel upgrade. A research project to develop MAPS able to provide accurate space resolution and time resolution better than 10 ps is ongoing at the University of Geneva, Switzerland. The strategy we followed is to produce a low-noise fast amplifier using silicon-germanium (SiGe) BiCMOS technology combined with a novel sensor concept.