First results from LHC October pilot beam test and laboratory measurements using BCM1F luminometer

To achieve the required high luminosity precision during the Run 3 LHC operations, the fast Beam Condition Monitor (BCM1F) was upgraded. It was rebuilt with new sensors, produced as a part of the Phase 2 Outer Tracker sensor production. The assembly and qualification of the detector quadrants were followed by the integration with Pixel Luminosity Telescope (PLT) and Beam Conditions Monitor for Losses (BCML1). It was installed inside the Compact Muon Solenoid (CMS) behind the CMS Pixel detector, at a distance of 1.8 m from the Interaction Point (IP). BCM1F will provide luminosity measurement as well as timing information with a sub-bunch crossing precision, enabling the measurement of beam-induced background. The poster will report on the improved BCM1F design, the commissioning and first results during the 2021 LHC Beam Test, prior to the start of Run 3.