The new pixel luminosity telescope of CMS at the LHC

Abstract

The Pixel Luminosity Telescope (PLT) is one of the newest additions to the Compact Muon Solenoid (CMS) detector for the Large Hadron Collider (LHC) Run II data taking period. On each side of the CMS detector it consists of eight 3-layer telescopes based on silicon pixel detectors that are placed around the beam pipe viewing the interaction point at small angle. A fast 3-fold coincidence of the pixel planes in each telescope provides a bunch-by-bunch measurement of the relative luminosity. In addition to the physics program of CMS, this measurement is useful for accelerator diagnostics and optimization. Particle tracking information sampled at a kHz rate allows collision products to be distinguished from beam background, provides a self-alignment of the detectors, and provides for continuous in-time monitoring of the efficiency of each telescope plane. After calibration of the delivered luminosity in Van der Meer scans of the LHC beam, the PLT is expected to reduce the uncertainty on the delivered luminosity of the LHC which is a crucial input for precision measurements of Higgs properties, determining particle production cross sections, and setting of mass limits on yet undiscovered particle production. An overview of the project, commissioning, and operational experience during this year's LHC running are presented.