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Description
The MALTA2 sensor is the second prototype in the MALTA family of Depleted Monolithic Active Pixel Sensors, developed using a modified 180 nm CMOS imaging process and optimized for operation in the high-radiation and high hit-rate conditions of future collider experiments. With a matrix of 224 × 512 pixels and a 36.4 $\mu$m pitch, MALTA2 is designed for fast charge collection, low noise, and low power operation. This work focuses on evaluating the performance of a MALTA2 variant incorporating very high doping of the $n^{-}$ layer, aimed at improving radiation hardness. Such a MALTA2 sample was irradiated up to a fluence of 5×$10^{15}$ 1 MeV $n_{eq}/cm^{2}$ and characterized in a dedicated test beam campaign at the CERN SPS using a 180 GeV hadron beam. The sensor maintained hit efficiencies above 95% up to 3×$10^{15}$ 1 MeV $n_{eq}/cm^{2}$, with a performance reduction observed at the highest fluence, in line with expectations for radiation-induced damage. Grazing angle measurements were performed to study the charge collection behavior and assess tracking performance across varying beam incidence angles. Cluster size evolution with incident angle provided insight into the depletion behavior after irradiation. The results from the very high doping will guide the development of prototypes featuring ultra-high $n^{-}$ layer doping, aiming to achieve greater radiation hardness in next-generation silicon tracking detectors.
