Silicon pixel detectors play an ever increasing role in modern high energy experiments, and fuctionality is continuously being added to address requirements such as speed, precision, rate, radiation hardness and timing capability. This seminar will discuss one such application; the hybrid silicon pixel detector system which has been developed for the LHCb Upgrade VELO (Vertex Detector). This forms part of the LHCb Upgrade detector, due to be installed in 2020, which will extend the LHCb programme of the study of CP violation and rare decays in the heavy flavour sector. The hybrid pixel system is based around the VeloPix ASIC, derived from the Medipix/Timepix family of chips. The VeloPix ASIC is optimised for speed and radiation hardness, and will be capable of reading out pixel sensors with 55 micron square pitch at hit rates of more than 900 Mhits/s. It shares many features with, and has been developed in synergy with, the Timepix3 and Timepix4 generation of ASICs, which are oriented towards medical applications. The hybrid pixel sensors will be mounted close to the LHCb beams on silicon cooling wafers incorporating internal micro channels where bi-phase CO2 coolant will circulate. In this way the VELO will remain very lightweight, while being able to operate in the very demanding environment of the LHCb Upgrade. The development of the system and the current status will be described.
