The Phase-1 Upgrade of the CMS pixel detector

The CMS experiment features a pixel detector with three barrel layers and two discs per side, corresponding to an active silicon area of 1 m$^{2}$ . The detector delivered high-quality data during LHC Run 1. However, the CMS pixel detector was designed for the nominal instantaneous LHC luminosity of 1·10$^{34}$cm$^{−2}$s$^{−1}$ . It is expected that the instantaneous luminosity will increase and reach twice the design value before Long Shutdown 3, scheduled for 2023. Under such conditions, the present readout chip would suffer from data loss due to buffer overflow, leading to significant inefficiencies of up to 16%. The CMS collaboration is presently constructing a new pixel detector to replace the present device during the winter shutdown 2016/2017. The design of this new detector will be outlined, the construction status summarized and the performance described.