Annealing of irradiated silicon strip detectors for the ATLAS experiment at CERN

ATLAS prototype n-in-n and p-in-n silicon strip detectors from several manufacturers were irradiated with 24 GeV protons at the CERN PS to a total fluence of 3 x 10(14) p/cm(2). This is equivalent to the maximum fluence expected in the strip detector part of the silicon tracker after 10yr of operation. The ATLAS semiconductor tracker will be operated at -7 degrees C. Yearly warm-up periods of 2 days at 20 degrees C and 2 weeks at 17 degrees C are foreseen for maintenance purposes (ATLAS inner Detector Technical Design Rep., 1997). To study the long-term effects of radiation damage and warm-up the detectors underwent controlled thermal annealing. The Ziock parameterisation was used to simulate the warm-up effects of 10yr on a shortened time scale (H.J. Ziock et al., Nucl. Instr. and Meth. A 342 (1994) 96), Using this parameterisation the same amount of anti-annealing gained during 10 yr of warm-ups can be reached by storing the detectors for 21 days at 25 degrees C. During the annealing period current-voltage and capacitance-voltage measurements were carried out at regular intervals. The full depletion voltage was then determined from the capacitance measurements and showed a clear dependency on the measurement frequency and temperature. The evolution of the full depletion voltage as a function of annealing time is compared to the Ziock parameterisation. (C) 1999 Elsevier Science B.V. All rights reserved.