Instrumentation at the LHC—The silicon tracking systems

For the experiments at the Large Hadron Collider at CERN the detectors in the vertex region and the tracking systems are very critical components for the success of the projects. Due to the harsh environment at the high intensity hadron collider these detectors are also the most challenging to construct. The design of the experiments started about 25 years ago. At this time silicon detectors as particle detectors for high energy physics experiments were still in their infancy. But, because of the huge progress made in developing this technology all LHC experiments finally employed silicon detectors and some experiments even constructed very large silicon systems. C experiments went into operation in 2009, and after two years of operation the performance of the detectors can now be evaluated. This paper gives an overview of the different silicon detector systems at LHC and summarizes the installed silicon detector types and dimensions.