Early stage of reverse annealing and projections for LHC experiments

Reverse annealing of radiation damage in silicon bulk has been studied with emphasis on its implications on LHC experiments. Predictions were shown to depend critically on the model used for reverse annealing dynamics. A set of 8 p/sup +/-n-n/sup +/ pad detectors was irradiated with neutrons to fluences from 2*10/sup 13/ to 2*10/sup 14/ n/cm/sup -2/. Time-development of defects at 20 degrees C for 100 days covered the expected annealing at LHC. A linear parameterization of this initial stage of reverse annealing with a slope parameter was used. The fluence dependence of the slope clearly proved that reverse annealing is indeed a first-order process. A large spread was observed in the slope even with identically treated detectors from the same production batch, the mean value corresponding to a reverse annealing time constant of 476 days. Two pad detectors were irradiated to 4*10/sup 13/ n/cm/sup -2/ and reverse annealing measured for a month at 60 degrees C. A fit with two exponentials was shown to adequately describe reverse annealing up to completion. (15 refs).