Running experience with the DELPHI pixel detector: Reflections on design characteristics and system features

The DELPHI experiment at LEP is the first collider experiment with hybrid pixel detectors contributing to its track reconstruction. The pixel detector has been installed in 1996 with the final DELPHI Silicon Tracker, an assembly of microstrip, ministrip and pixel detectors optimized for the operation at LEP2. It was completed for the physics period in 1997. The pixel detector comprises 1.2 million detector cells of 330 × 330 µm 2. 152 detector modules are arranged in 4 inclined cone-shaped layers which cover polar angles from 10 • to 25 •. Experience on the system's features has been gained during three years of operation. The article intends to provide information on positive and critical aspects which might be useful for designers of pixel detector systems in forthcoming experiments.