Instrumentation of a Level-1 track trigger in the ATLAS detector for the high luminosity LHC

The Large Hadron Collider will be upgraded in order to reach an instantaneous luminosity of L = 5 × 10³⁴ cm^-2 s^-1. A challenge for the detectors will be to cope with the excessive rate of events coming into the trigger system. In order to maintain the capability of triggering on single lepton objects with momentum thresholds of p_T ~ 25 GeV, the ATLAS detector is planning to use tracking information at the Level-l (hardware) stage of the trigger system. Two options are currently being studied: a L0/L1 trigger design using a double buffer front-end architecture and a single hardware trigger level which uses trigger layers in the new tracker system. Both options are presented as well as results from simulation studies.