CERN -- European Laboratory for Particle Physics

Addendum to proposal P53

Solid state detectors at liquid nitrogen temperatures LHEP Bern-BNL-CERN-INFN/UnivFlorence-Univ. Geneva-Glasgow Univ.-HUT Espoo-HYPRES Inc.-IEKP Karlsruhe-LIP-Univ.Ljubljana-TU Munich-INFN/Univ. Naples-Saitama Univ.-ETL Tsukuba-VTT Espoo;LHCC 98-27/P53 Add.1)

Status: Approved for a first year

LDRB) LHCC

Spokesman: T. Niinikoski

Abstract: The recent advances in Si and diamond detector technology givehope of a simple solution to the radiation hardness problem for vertex trackersat the LHC. In particular, we have recently demonstrated that operatinga heavily irradiated Si detector at liquid nitrogen LN2) temperature resultsin significant recovery of Charge Collection Efficiency CCE). Among otherpotential benefits of operation at cryogenic temperatures are the use oflarge low-resistivity wafers, simple processing, higher and faster electricalsignal because of higher mobility and drift velocity of carriers, and lowernoise of the readout circuit. A substantial reduction in sensor cost couldresult. Several CERN experiments are potential users of cold radiation hardtracking devices.

The first goal of the proposed extension of the RD39 programme is todemonstrate that irradiation at low temperature in situ during operationdoes not affect the results obtained so far by cooling detectors which wereirradiated at room temperature. In particular we shall concentrate on processesand materials that could significantly reduce the final detector cost. Thesecond goal is to demonstrate the operation of existing radiation-hard CMOSreadout electronics at LN2 temperature, and to measure discrete device characteristicsat these temperatures, so that their parameters can be extracted and optimisedcircuits can be designed. The third goal is to demonstrate that low-masscooling at LN2 temperature is feasible at a reasonable cost, and that theelectrical and optical feedthroughs of a large system can be mastered.

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MS 29 Oct 98