Investigation of radiation damage in the SLD CCD vertex detector

Early in the operation of the SLD CCD vertex detector (VXD3) at the SLC, radiation damage to the CCDs was observed. It is well known that low-energy light particles (electrons and photons) are a few orders of magnitude less effective than heavy particles (neutrons or heavy charged particles) in the generation of radiation damage effects in silicon. The SLD environment was known to be dominated by electrons and photons with a small fraction of neutrons. The estimated radiation damage by these particles cannot account for the observed damage. Therefore, this damage is puzzling. A CCD-based detector is a leading option for vertex detection at the future linear collider (LC). A full understanding of background models in LCs and the associated damage is needed. Earlier results on neutron damage to an SLD CCD were reported at the 1999 IEEE NSS, and these new results complement our old results. In addition to tests on controlled exposures of individual CCDs, we have studied the nature of the traps produced in the SLD vertex detector to assess their origin-whether heavy or light particles.