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The VErtex LOcator (VELO) is the silicon microstrip vertexing and triggering sub-detector of the LHCb experiment. It consists of a series of forward disks with the active region ex- tending to just 8 mm from the LHC beams. The current status of the VELO is presented. Due to the high radiation environment, the VELO may have to be replaced after some years, possibly with new materials. A candidate material is Czochralski silicon. We present here promising new results on the first test beam of a large, high resistivity Czochralski microstrip silicon detector read out with LHC speed electronics. The performance was studied before and after irradiation with high energy protons. A signal to noise of over 20:1 was obtained from the detector and significant charge collection efficiencies were measured at relatively modest voltages after a fluence of 4.3 × 1014 1 MeV neutron equivalents (neq) per cm². Studies using the Transient Current Technique probed the electric field within MCz test detectors and proved that MCz silicon does not type invert up until a radiation level of at least 5 × 1014 24 GeV/c p/cm². This would mean the VELO could possibly replace, in a potential upgrade, n+ -on-n DOFZ sensors and the complicated processing involved, for standard p+ -on-n processing with MCz. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic Czochralski (MCz) silicon has recently become a promising material for the development of radiation tolerant detectors for future high-luminosity HEP experiments. A thorough study of 24GeV/c proton-irradiated p+-in-n Float Zone (FZ) , Diffusion Oxygenated Float Zone (DOFZ) and MCz silicon detectors has been conducted using the standard radiation damage characterization tools IV and CV, the Transient Current Technique (TCT) and annealing studies. The first systematic study on the effective trapping time in MCz silicon has been performed. The results show that the introduction rate for the traps responsible for the degradation of the effective trapping time for MCz material agrees with the introduction rate for FZ and DOFZ silicon. From the behaviour of the depletion voltage as a function of proton fluence and through the TCT technique, it has been shown that by a radiation fluence of 5×1014 p/cm2 the depletion voltage has passed its minimum value without type inversion. An annealing study compares the evolution of the effective trapping time, the effective space charge density and the current-related damage parameters for MCz and DOFZ silicon. [Copyright &y& Elsevier]