Radiation Damage in Silicon Detectors Caused by Hadronic and Electromagnetic Irradiation

Abstract

The report contains various aspects of radiation damage in silicon detectors subjected to high intensity hadron and electromagnetic irradiation. It focuses on improvements for the foreseen LHC applications, employing oxygenation of silicon wafers during detector processing (result from CERN-RD48). An updated survey on hadron induced damage is given in the first article. Several improvements are outlined especially with respect to antiannealing problems associated with detector storage during LHC maintenance periods. Open questions are outlined in the final section, among which are a full understanding of differences found between proton and neutron induced damage, process related effects changing the radiation tolerance in addition to the oxygen content and the lack of understanding the changed detector properties on the basis of damage induced point and cluster defects. In addition to float zone silicon, so far entirely used for detector fabrication,Czochralski silicon was also studied and first promising results are shown. The other three papers deal with gamma induced damage including also defects introduced either by processing steps or being inherent to the as grown silicon. However the focus is on measurements after gamma irradiation in a wide dose range. Both the changes in detector properties and defect characterisations have been studied. For the first time it is shown that in contrast to a standard process oxygenated silicon detectors withstand an irradiation dose of up to 1 Grad with only minor deterioration. Also it is shown for the first time that in this case the detector properties can directly be explained by the damage induced point defects. This 1:1 correlation is extremely promising for all future defect engineering work.