The CMS Phase2 upgrade: the MTD detector.

The Compact Muon Solenoid (CMS) detector at the CERN Large Hadron Collider (LHC) is undergoing an extensive upgrade program to prepare for the challenging conditions of the High-Luminosity LHC (HL-LHC). A new timing detector in CMS will measure minimum ionizing particles (MIPs) with a time resolution of $30\mbox{--}40 {ps}$ for MIP signals at a rate of $2.5 {Mhit/s}$ per channel at the beginning of HL-LHC operation. The precision time information from this MIP Timing Detector (MTD) will reduce the effects of the high levels of pileup expected at the HL-LHC, bringing new capabilities to the CMS detector. The MTD will consist of a central part, the barrel timing layer (BTL), based on LYSO:Ce crystals coupled to silicon photomultipliers, and an endcap region, the endcap timing layer (ETL), instrumented with low-gain avalanche diodes (LGADs). In this contribution we present an overview of the MTD design, describe the latest progress towards prototyping and production, and show test beam results demonstrating the achieved target time resolution.