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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:59 |
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Conference: Bucharest University Faculty of Physics 2005 Meeting
Section: Nuclear and Elementary Particles Physics
Title:
Silicon detectors: from radiation hard devices
operating beyond LHC conditions to characterisation of primary fourfold coordinated vacancy defects
(Work in the frame of CERN RD-50 Collaboration)
Authors:
I. Lazanu (1)
S. Lazanu (2)
Affiliation:
(1) University of Bucharest, Faculty of Physics,
POBox MG-11, Bucharest-Magurele, Romania
e-mail: i_lazanu@yahoo.co.uk
(2) National Institute for Materials Physics,
POBox MG-7,Bucharest-Magurele, Romania,
e-mail: lazanu@infim.ro
E-mail
i_lazanu@yahoo.co.uk
Keywords:
new colliders, silicon detectors, hadrons, leptons, radiation damage, primary defects, kinetics of defects
Abstract:
In this contribution, the physics potential at future hadron colliders, the requirements for detectors and possible scenarios for radiation environments at LHC and its upgrades in energy and luminosity as Super-LHC and Very-LHC respectively, are discussed.
Silicon detectors will be used extensively in experiments at these new facilities where they will be exposed to high fluences of fast hadrons. The principal obstacle to long-time operation arises from bulk displacement damage in silicon, which produces primary point defects, and which, in the presence of impurities increases the leakage current in the detector, decreases the satisfactory Signal/Noise ratio, and increases the effective carrier concentration (thus depletion voltage), which ultimately increases the operational voltage of the device beyond the breakdown voltage. These effects must be considered in the design of semiconductor detectors for high energy physics.
An important old observation consists in the good or reasonable agreement between theoretical models and data for the time evolution of the leakage current and effective carrier concentration after lepton or gamma irradiation, and discrepancies up to 2 orders of magnitude (smaller in model calculation) after hadron irradiation, and this in conditions where a reasonable accord is obtained between experimental and calculated concentrations of complex defects.
We argue that the problem related to the different discrepancies between model calculations and experimental data for macroscopic detector characteristics after lepton and hadron irradiation could be solved naturally considering the existence, as primary defects, of interstitials, classical vacancies, and of the new theoretically predicted fourfold coordinated silicon vacancy defect (SiFFCD), In this work, starting from experimental data, in the frame of a theoretical model, it was possible to estimate indirectly some characteristics of the SiFFCD defect.
Implications for the behaviour of silicon detectors, especially during continuous irradiation in the environment of LHC up-grades is also discussed.
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