Radiation damage studies of DØ Silicon Sensors

The D0 Silicon Microstrip Tracker has been operating for two years in the D0 experiment at Fermilab. The existing silicon tracking system has limited lifetime to microdischarge effects at high bias voltage. Radiation studies of the current detector are described. We describe the design of the RunIIb replacement and discuss irradiations performed at Kansas State University. The hardness factor is found to be 40% lower than the value calculated from non ionizing energy loss scaling. I. LIFETIME STUDIES OF THE DO RUN IIA SILICON DETECTOR The D0 Silicon Microstrip Tracker (D0SMT) was commissioned in 2001. The detector consists of 792,000 readout channels in 672 detector modules. Originally designed for an integrated luminosity of 2 fb -1 ; the luminosity goal for the Tevatron collider was increased to ~15 fb -1 with the expectation that a Higgs discovery was within reach. The increased luminosity implies a radiation dose well in excess of the design value of ~3× 10 13 one MeV neutrons/cm 2 equivalent.