{'fraction_non_alphanumeric': 0.02151238591916558, 'fraction_numerical': 0.02998696219035202, 'mean_word_length': 5.189516129032258, '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}}
Radiation damage and recovery properties in three kinds of polymer optical fiber exposed γ-ray irradiation

The radiation damage and recovery of polymethylmethacrylate (PMMA), Polystyrene PS and polycarbonate (PC) optical fiber under γ-ray irradiation was researched experimentally. The visible light transmission rate of the POF under different irradiation dose was measured. The results indicated that the radiation damage of three kinds of POF was wavelength-dependent. Under lower dose below 1000Gy, the transmission rate decreased identical in the whole visible light range. When the irradiation dose exceeded 5000Gy, the transmission rate reduced obviously, and the transmission rate indicated that the visible light transmission rate of the POF at the range of 400nm to 500nm comparing 600nm to 800nm, decreased seriously. The transmission rate of both PMMA and PC have an evident peak value in the range 550nm-650m, and that of PS has wide peak value at the range 500-700nm. In addition, we measured the recovery of three kinds of POF five times following irradiation at the wavelength 632nm. Under low dose irradiation 100 Gy, the transmission rate reduced a little, and the irradiation damage can recover during a short time. When the irradiation dose reached 1000 Gy, the recovery process need longer time. When the irradiation dose exceeded 5000 Gy, the transmission rate reduced obviously, and the recovery process is slow and the irradiation damage can't recover completely, that indicated fiber suffered lasting damage.