ATLAS Level-1 Endcap Muon Trigger for Run 3

The Level-1 endcap muon trigger in the ATLAS experiment is a hardware trigger for endcap regions, which identifies muons with high transverse momentum by combining information from fast-response muon detectors. The Large Hadron Collider at the CERN is scheduled to begin the physics data-taking from 2021 as Run 3. An upgrade program of the Level-1 endcap muon trigger is required o improve trigger performances for Run 3. New muon detecters called New Small Wheel and RPC-BIS78 will be installed by the upgrade. Thus, new trigger processor board called Sector Logic has been developed to handle information from the new detectors. This paper describes the upgrade program of the Level-1 endcap muon trigger, particularly emphasizing on the new algorithm in the Sector Logic as well as the expected trigger performance.