The fast beam condition monitor as standalone luminometer of the CMS experiment at the HL-LHC

Abstract For the Phase-2 CMS upgrade for High-Luminosity LHC, a luminosity uncertainty of 1% is targeted. To achieve this goal, measurements from multiple luminometers with orthogonal systematics are required. A standalone luminometer, Fast Beam Condition Monitor (FBCM) being designed online bunch-by-bunch measurement. The sampling time resolution ∼0.7 ns also enables measurement beam-induced backgrounds. In paper, hardware architecture and readout protocol FBCM described. expected performance simple behavioral model front-end comprising constant fraction discriminator discussed, although final implementation in ASIC still under discussion. Simulation results show that will provide required statistical deviation linearity by employing 336 silicon-pad sensors, each an area about 3 mm 2 . addition, sensitivity to as low 6000 electrons satisfy longevity constraints exposure 1 MeV neutron equivalent fluence 3.5 × 10 15 per cm