Operational Issues of the Present CMS Pixel Detector

The core of the CMS experiment is a three-layer pixel detector. Installed in 2008, the CMS pixel system is essential for track seeding and reconstruction of secondary vertexes. The presentation will summarize the operational experience of the first four years of collisions at the LHC. We will present the measured performance evolution as the instantaneous luminosity delivered increased by several orders of magnitude, including dynamic data-losses, efficiency and resolution. The focus of the presentation will be on the operational challenges encountered to present. Moreover the impact of radiation on on-detector electronics, including both single-event upsets and cumulative changes in performance, are discussed. Leakage current and depletion voltage are monitored with increasing fluence. Methods for addressing the challenges of these measurements in the context of ongoing detector operations are discussed.