A muon trigger upgrade with high transverse momentum resolution for the ATLAS detector at the High-Luminosity LHC

The Level-1 trigger for muons in ATLAS is based on trigger chambers (RPCs, TGCs) with excellent time resolution which are able to identify muons coming from a particular beam crossing. It is proposed to use precision tracking chambers (MDTs) for improving the transverse momentum resolution at the Level-1 trigger for the phase II of the LHC, the so-called High-Luminosity LHC. We present the new trigger algorithm and the architecture of the electronics as well as a prototype test. We demonstrate the performance for a transverse momentum threshold of 20 GeV using experimental data.