X-ray irradiation studies on the Monopix DMAPS in 150 nm and 180 nm

Monolithic active pixel sensors with depleted substrates present a promising option for pixel detectors in high-radiation environments. High-resistivity silicon substrates and high bias voltage capabilities in commercial CMOS technologies facilitate depletion of the charge sensitive volume. TJ-Monopix2 and LF-Monopix2 are the most recent large-scale chips in their respective development line, aiming for the ATLAS Inner Tracker outer layer requirements. Those include a tolerance to ionizing radiation of up to 100 Mrad. It was evaluated by irradiating both devices with X-rays to the corresponding ionization dose, showing no significant degradation of the performance at 100 Mrad and continuous operability throughout the irradiation campaign.