In beam performances of the MIMOSIS-2.1 CMOS Monolithic Active Pixel Sensor

MIMOSIS is a CMOS Monolithic Active Pixel Sensor developed to equip the Micro Vertex Detector of the Compressed Baryonic Matter (CBM) experiment at FAIR/GSI. The sensor will combine an excellent spatial precision of 5 µm with a time resolution of ∼5 µs and provide a peak hit rate capability of ∼ 80 MHz/cm 2 . To fulfill its task, MIMOSIS will have to withstand ionising radiation doses of ∼ 5 MRad and fluences of ∼ 7 × 10 13 n eq /cm 2 . This paper introduces the reticle size full feature sensor prototype MIMOSIS-2.1, which was improved with respect to earlier prototypes by adding on-chip grouping circuits and by improving the analog power grid. Moreover, it features for a first time a 50 μm epitaxial layer, which is found to improve the performances of the non-irradiated device significantly. We discuss the in beam sensor performances as measured during beam tests at the CERN-SPS.