LHCb-VELO silicon microstrip detectors
Extreme radiation hardness is required to the LHCb-VELO devices (the closest microstrip detectors to the interaction point in LHC, therefore exposed to the highest fluences. The devices have been designed from the University of Liverpool (see Phil Turner's home page) incorporating all the available techniques to improve their radiation hardness. You can find here a summary of some of the results.
O
xygenated siliconThe oxygenated substrate could improve the tolerance of the LHC-b vertex
detectors, by reducing the deterioration of the full depletion voltage with
fluence and try to improve the charge collection efficiency at lower voltages. A
possible scenario for this solution is
here discussed.
Here you find some preliminary results of
charge collection efficiency and noise
for a detector partially irradiate (in the innermost region) detector with 24
GeV/c protons to 3 1014 cm-2.
N-side read-out
The biggest improvement to the radiation tolerance of segmented silicon detectors is given by reading-out the n-side segmented electrodes rather than the p-side (n-in-n geometry as opposite to p-in-n). The LHCb-VELO detectors have been finally made with this geometry for maximum radiation hardness. Here you can find comparisons between n and p-side read-out, to support the n-in-n choice.
First Laboratory measurements on a LHCb-phi prototype detector.
A fine spot laser system has been set-up in Liverpool to allow the full characterisation of microstrip detectors. The system is particularly suitable to measure the properties of non-homogeneously irradiated detectors. The inhomogeneous fluence received by silicon sensors during the operation is a concern for the LHCb experiment. Here I put the first draft to resume the results of the measurements on LHCb-phi type detector partially irradiated with 24 Gev/c protons: 14/03/2001 Results with a partially irradiated LHCb-phi type detector.
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