{'fraction_non_alphanumeric': 0.04059040590405904, 'fraction_numerical': 0.027675276752767528, 'mean_word_length': 4.896739130434782, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Proton induced damage after laboratory cold irradiation in CCD47-20 CCDs for CHEOPS

The CCD47-20 detector of CHEOPS (CHaracterizing ExOPlanet Satellite, ESA/Switzerland), operated at -45°C, is developing an increasing number of hot pixels in orbit, due to particle-induced radiation damage in its 700 km, sun-synchronous dawn/dusk orbit. While the satellite offers the possibility to raise the detector’s temperature to well above +20°C, it is not clear whether this could have a beneficial effect on the hot pixel distribution, and which temperature and duration would be required. To inform the mission on the potential benefits of in-orbit annealing, we irradiated CCD47-20s from the CHEOPS flight production batch at -45°C with protons. After irradiation, the hot pixels were monitored for 7 days at -45°C Subsequently, the temperature was raised step-wise (up to +80°C) for 12 hrs, each step followed by characterisation at -45°C. A significant reduction in the hot pixel count was observed at each step. A recommendation for a possible in-orbit annealing procedure was derived.