RADIATION TESTS OF ATLAS FULL-SIZED N-IN-N PROTOTYPE DETECTORS

ATLAS Technical Proposal, CERN/LHCC/94-43 has adopted n-side read out single-sided detectors as the baseline technology for the silicon micr ostrips due to the anticipated radiation tolerance of such a design AT LAS Inner Detector Technical Design Report, CERN/LHCC/97-17. This resu lts from the reasonable efficiencies anticipated for charge collection , even when the detectors are run well below the final depletion volta ge. Full-sized prototypes 64 x 63.6mm(2) detectors have been produced with a range of manufacturers to a common specification and shown to w ork well in test-beam with ATLAS electronics. A selection of detectors was also scanned in the CERN PS beam for runs of two weeks giving an integrated dose over the full surface of 2 x 10(14) p/cm(2). This dose corresponds to the highest charged hadron fluence expected in 10 yr o f operation in ATLAS. Results are presented on these detectors both fr om parametric measurements and from studies using analogue LHC speed e lectronics. The detectors are shown to remain fully operational after these doses and to yield high signal/noise for read-out of 12cm strip length. The performance partially depleted is also shown to match expe ctations and operation at down to half the final depletion voltage giv es adequate efficiencies. Uncertainties in the anticipated dose and da mage effects argue strongly for this additional robustness in detector s which must operate with very limited access in the hostile environme nt of the LHC for 10 yr. (C) 1998 Elsevier Science B.V. All rights res erved.