Occupancy studies for the LHCb Run4 Mighty Tracker

Occupancy studies are reported for the downstream tracking stations in which the effects of secondary particle production in detector materials are considered. A simplified model of the material description for the Inner Tracker (IT) silicon pixel detector proposed for LHCb LS3 enhancements has been developed in Geant4 to facilitate this study. The sources of secondary particles have been identified to characterise the contribution of various sub-detectors to the occupancy in the scintillating fibres (SciFi) of the downstream tracking stations. The impact of the IT material on occupancy is examined for two material descriptions: with and without DCDC converters. Two possible modifications of the SciFi to accommodate the IT are also compared. Simulated event samples have been produced for each detector geometry scenario, as well as for the current Upgrade I configuration.