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ATLAS
Abstract:
Muon chamber technologies are studied in the context of the upcoming ATLAS detector upgrade for the high-luminosity LHC. The efficiency and resolution of a prototype thin-gap triplet resistive plate chamber (RPC) is derived from 2017 muon test beam data. The response of the RPC, which has a nominal gas gap voltage of 5600 kV, is evaluated across a voltage range 4400 to 6000 kV. The time resolution is around half a nanosecond. The spatial resolution is around 1 cm. Then, the muon tracking resolution and muon efficiency is derived for a Monitored Drift Tube (MDT) chamber operated with a new amplifier-shaper-discriminator (ASD) chip that is intended for installation on all existing ATLAS MDTs. The data was gathered in 2018 in a muon beam and gamma irradiation facility. Applying the maximum expected HL-LHC gamma background was associated with a 1% efficiency loss and 40 μm resolution loss compared to muons alone. A much higher gamma background of 240 kHz/channel (2 kHz cm −2 ) was associated with a further 5% efficiency and 130 μm resolution loss. The conclusion of the tests is that both the new RPC design and the new ASD chip meet the requirements for the ATLAS upgrade.
