Commissioning of the BIS78 pilot project of the phase-1 upgrade of the ATLAS muon spectrometer

The Monitored Drift Tube (MDT) provides precise tracking and momentum measurement in the ATLAS muon spectrometer. To accommodate higher event rates and provide better fake rejection in the High Luminosity LHC, a new integrated chamber with small-diameter MDT (sMDT) and thin Resistive Plate Chambers (tRPC) had been developed and will be installed into barrel inner layer of the muon detector for the phase-2 upgrade. The BIS78 project serves as a pilot project for the barrel inner layer upgrade (1 < |η| < 1.3). During the LHC LS1 shutdown (2019-2021) several sMDT+tRPC chambers have been installed and operated in the ATLAS detector. An overview of the commissioning status of BIS78 in the ATLAS experiment will be presented.