40 MHz readout of CMS silicon modules in a high intensity beam

Abstract

In order to maintain its outstanding performance under the challenging conditions brought by the high-luminosity LHC, the CMS collaboration is preparing the production of a new outer tracker detector. The upgraded detector modules will feature two silicon sensors and the ability of reading out correlated clusters, or stubs, compatible with high transverse momentum particles at the full 40 MHz collision rate. With the detector design being finalised and mass production planned to start during the second half of 2024, the scalability of the readout system and the study of the commissioning and characterisation of the detector in realistic conditions are ever-more pressing.In this context, a joint beam-test was organised in collaboration with the MUonE collaboration where twelve modules were placed in an asynchronous muon beam line reaching particle rates of about 50 MHz, with the full stub stream being recorded to disk triggerless. The experiment and read-out chain is outlined, the commissioning procedures and operational challenges discussed and resulting system performance are presented.