The PLT: A Luminosity Monitor for CMS Based on Single-Crystal Diamond Pixel Sensors

The Pixel Luminosity Telescope (PLT) system is an innovative luminosity monitor being developed as an early upgrade for the CMS detector at the LHC. An essential feature of the PLT is the use of single crystal diamond, grown by chemical vapor deposition, as the active sensor material. The radiation hardness of diamond, along with its lack of need for active cooling, are key to the design and functioning of the PLT. While diamond sensors have been used in several collider experiments, primarily for monitoring of beam conditions, these have mostly been based on poly-crystal diamonds. The PLT will be the first device to rely on the use of a single-crystal diamond and the first to use diamond pixel sensors. We will discuss the important role that a single-crystal diamond will play in the PLT operation. We will contrast single-crystal to poly-crystal diamond sensors, provide an overview of the PLT concept, and present results on its performance.