The Phase 1 Upgrade of the CMS Pixel Detector

The LHC is running successfully, and it is expected that the instantaneous luminosity will surpass the design value of $10^{34} \rm cm^{-2}s^{-1}$ before 2020. CMS has planned the so-called phase 1 upgrade between the two LHC long shutdowns to replace the current silicon pixel detector. The upgrade detector will be capable of fully exploiting the increased luminosity. The upgrade detector will decrease the material budget significantly. The newly designed readout chip will improve the dead-time during high-rate and high-luminosity data taking. In this paper, we present the design of the upgrade detector along with the expected improvement and physics performance. The status of the project is also reported, including details of various detector components.