| FCAL is a worldwide detector Research & Development collaboration, responsible for the instrumentation of the angular region forward of the coverage of Endcap ECAL, one of the subsystems of SiD, a general purpose detector proposed for the International Linear Collider (ILC). The angular coverage of this forward region is completed by two detectors, the Luminosity Calorimeter (LumiCal) and the Beam Calorimeter (BeamCal). BeamCal, a tungsten sampling calorimeter, is designed to reconstruct showers of electrons, positrons and photons that emerge from the interaction point of the collider with angles between 5 and 50 milliradians. For the innermost radius of this calorimeter, radiation doses at shower-max are expected to reach 100 MRad per year, primarily due to minimum-ionizing electrons and positrons that arise in the induced electromagnetic showers of e+e- "beamstrahlung" pairs produced in the ILC beam-beam interaction. However, radiation damage to calorimeter sensors may be dominated by hadrons induced by nuclear interactions of shower photons, which are much more likely to contribute to the non-ionizing energy loss that has been observed to damage sensors exposed to hadronic radiation. After brief review of two silicon crystal wafer fabrication technologies investigated (magnetic Czochralski (mCZ) and Float-Zone (FZ) processes) and the mechanism of radiation damage in silicon crystal, the results of SLAC Experiment T-506 are reported in this thesis. Four different types of silicon diode sensors were exposed to doses of radiation induced by showering electrons of energy 3.5-10.6 GeV. By embedding the silicon sensor under irradiation within a tungsten radiator, the exposure incorporated hadronic species that would potentially contribute to the degradation of a sensor mounted in a precision sampling calorimeter. Depending on sensor fabrication technology, efficient charge collection was observed for doses as large as 220 MRad. |
