Roy Wastie

Abstract:

The design and technology of the silicon strip detector modules for the Semiconductor Tracker (SCT) of the ATLAS experiment have been finalised in the last several years. Integral to this process has been the measurement and verification of the tracking performance of the different module types in test beams at the CERN SPS and the KEK PS. Tests have been performed to explore the module performance under various operating conditions including detector bias voltage, magnetic field, incidence angle, and state of irradiation up to 3×1014 protons per square centimetre. A particular emphasis has been the understanding of the operational consequences of the binary readout scheme. © 2004 Elsevier B.V. All rights reserved.

Abstract:

The individual components of the semiconductor tracker (SCT) optical links were observed to be more than adequate in terms of radiation tolerance, with respect to total dose effects. Thus, complete links were proven sufficiently resistant to single event effects. Active components were already purchased and devices from individual wafers radiation qualified to ensure the maintenance of the necessary standards of radiation tolerance during production.

Abstract:

A large sample (96) of epitaxial Si PIN photodiodes has been irradiated by approximately 1 MeV neutrons and 24 GeV protons with fluences up to 10¹⁵ equivalent 1 MeV neutrons cm^-2 in order to test their suitability for use in the optical readout of the ATLAS semiconductor tracker and pixel detector at the CERN Large Hadron Collider. After an initial reduction of 30% the responsivity remains constant up to the maximum fluence. The rise and fall times are not significantly affected and remain below 1 ns. Although the dark current increases linearly with increasing neutron fluence, its level remains below 100 nA which is negligible in comparison to the operating photocurrent which is above 100 μA. Enhanced ageing studies at 60 °C have also been carried out and no failure has occurred after an equivalent of 360 years of operation.