Relative nonlinearity of BRIL luminometers derived from CMS $\mu$ scans

The CMS Beam Radiation Instrumentation and Luminosity (BRIL) Project is devoted to the simulation and measurements of beam conditions and luminosity for CMS. One of the BRIL tasks is the luminosity monitoring and calibration of the detectors to obtain the luminosity. For precise calibration of the luminosity it is important to understand the influence of nonlinear effects on single bunch instantaneous luminosity evaluated from measurements of a luminometer. These proceedings present the method to estimate nonlinearity of a luminometer based on data from $\mu$ scans, which are beam scans performed at conditions optimized for nonlinearity studies.