Study of radiation damage in silicon detectors for high ... - F9

1IntroductionSilicon detectors play an essential role in modern particle physics experiments. Theyexhibit fast and linear response to ionising particles, are compact and have good energyresolution. Highly developed techniques of semiconductor processing allow production ofcomplex structures on a micron scale. Silicon detectors are thus an obvious choice forcompact and fast tracking detectors with excellent spatial resolution 1 and are a part ofbasically all modern particle physics detectors. They are usually used as the innermostpart of tracking systems and play a crucial role in reconstruction of interaction vertices.In the rst decade of the next millennium the Large Hadron Collider (LHC) [2](gure 1.1) will be in operation at the European laboratory for particle physics (CERN). Itwill provide high energy (14 TeV) proton-proton collisions with high luminosity (10 33 /cm 2 sduring low and 10 34 /cm 2 s during high luminosity running). This opens a wide range ofphysics opportunities, among which the origin of mass is a major focus of interest. Oneof the possible manifestations of the spontaneous symmetry-breaking, responsible for theorigin of mass, could be the existence of the Higgs boson. The ability to search for theHiggs boson is therefore used as a prime criterium in designing the detectors. Togetherwith demands necessary for the study of some other processes (supersymmetry, B-physics)that will be accessible at LHC, it determines the basic design features of detectors at LHC[3, 4, 5]. Their main features are good electromagnetic calorimetry, ecient tracking athigh luminosity, tau and heavy-avour vertex reconstruction and stand-alone precisionmuon momentum measurements.This work was done in scope of the ATLAS collaboration, which is building oneof the large experiments at LHC. The overall design of the ATLAS detector (gure 1.2)is described in [4] and will not be discussed here. We shall only briey describe theinner detector (ID) [6], used for charged particle tracking. A superconducting solenoid is1Intrinsic resolutions as low as1m were obtained with silicon strip detectors [1].5