A proposed luminosity monitor for CMS based on small angle diamond pixel telescopes

Measurement and monitoring of the luminosity in the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) at CERN will be essential both for physics measurements (e.g., production cross-sections of top, Higgs and SUSY) and for accurate simulation of rate dependent detector characteristics. Our proposal for a CMS luminosity monitoring system consists of a set of small angle diamond pixel telescopes. These telescopes are situated close to the beam pipe where radiation levels are very high and room for mechanical structures and services is quite limited. The CMS pixel readout chip provides a fast over-threshold signal that will be used to monitor the bunch-to-bunch luminosity variations by counting the number of particles that hit the telescope array in each beam crossing. The proposed system will determine the individual bunch-to-bunch luminosity variations to a precision of better than 1% over a 1 s time scale.