Charge collection properties of heavily irradiated epitaxial silicon detectors

Detectors processed on epitaxial silicon seem to be a viable solution for the extreme radiation levels in the innermost layers of tracking detectors at upgraded LHC (SLHC). A set of epitaxial pad detectors of 50 and 75μm thicknesses (ρ=50Ωcm) was irradiated with 24GeV/c protons and reactor neutrons up to equivalent fluences of 1016cm-2. Charge collection for minimum ionizing electrons from a 90Sr source was measured using a charge sensitive preamplifier and a 25 ns shaping circuit. The dependence of collected charge on annealing time and operation temperature was studied. Results were used to predict the performance of fine pitch pixel detectors proposed for SLHC.