Data:Radiation-induced polymer stiffening for amplified Bragg shift in FBG radiation dosimeters

1 FTIR Data of PDMS Samples under Various Irradiation Doses and Conditions1.1. The chemical structures of PDMS samples subjected to vacuum irradiation, air irradiation, and different high-dose gamma irradiation levels were characterized using a Fourier Transform Infrared Spectrometer (FTIR), with absorbance-wavenumber data files obtained. Measurements were performed in Attenuated Total Reflection (ATR) mode, with a scanning range of 4000 cm⁻¹ to 500 cm⁻¹.1.2. High-Dose Gamma Pre-Irradiation Description: Uniform irradiation was conducted using an industrial-grade Co-60 gamma source at the Irradiation Center of Nanjing University of Aeronautics and Astronautics. The dose rate was 6.16 kGy/h, with total absorbed doses of 60 kGy, 80 kGy, 100 kGy, and 120 kGy.1.3. Description of Absorbance-Wavenumber Tabular Data for Different Air Groups: The first column represents absorbance; subsequent columns correspond to wavenumbers (cm⁻¹) for PDMS samples under air conditions at 0, 60, 80, 100, and 120 kGy, respectively.1.4. Description of Absorbance-Wavenumber Tabular Data for Vacuum and Air Control Groups: The first column represents absorbance; subsequent columns correspond to wavenumbers (cm⁻¹) for PDMS samples under 40 kGy + Air, 40 kGy + Vacuum, 0 kGy (background control group), respectively.  2 Crosslink Density Data of PDMS Samples under Various Irradiation Doses and Conditions2.1. The crosslink density of irradiated specimens was quantified using the Flory–Rehner equation. Equilibrium swelling tests were conducted under constant temperature (25°C) and light-free conditions, using toluene as the swelling solvent. Irradiated PDMS samples were weighed (initial mass recorded), immersed in a sufficient volume of toluene for thorough swelling, and periodically weighed until consecutive measurements stabilized, indicating equilibrium swelling mass was achieved (typically within 18–48 hours, influenced by ambient temperature and sample volume).2.2. PDMS Samples: Small specimens with thickness of 1 mm and dimensions of 5 mm × 5 mm. Toluene volume exceeded sample volume by 10 to 100 times to ensure complete swelling.2.3. Initial and final equilibrium swelling masses were measured using a high-precision electronic balance. Five PDMS samples per irradiation condition and dose were tested to minimize experimental error. Error sources include weighing inaccuracies and intrinsic sample variations.2.4. Tabular Data Description: Column 1: Irradiation dose; Column 2: Crosslink density under air conditions; Column 3: Crosslink density under vacuum conditions.  3 Young's Modulus Data of PDMS Samples under Various Irradiation Doses and Conditions3.1. Tensile testing of irradiated PDMS samples was performed using a WDW-100 electronic universal testing machine. Young's modulus was determined from the slope of the stress-strain curve.3.2. PDMS Samples: Dumbbell-shaped specimens prepared according to the national standard Type 4 dumbbell mold.3.3. Experimental data were obtained directly from tensile tests. Three PDMS samples per irradiation condition and dose were tested to reduce experimental error. Error sources include uncertainties in calculating the stress-strain curve slope and intrinsic sample variations.3.4. Tabular Data Description: Column 1: Irradiation dose; Column 2: Young's modulus under air conditions; Column 3: Young's modulus under vacuum conditions.  4 Temperature Response Data of Bare FBG Sensors4.1. Temperature response experiments were conducted on bare FBGs subjected to different high-dose gamma irradiation levels using a temperature and humidity chamber and a Beijing Xizhu SuperHawk6000 fiber Bragg grating interrogator.4.2. Temperature Range: 20, 30, 40, 50, and 60°C, with a 20-minute stabilization period at each temperature.4.3. All bare FBGs were laid flat in a plastic box to minimize potential micro-strain during handling and ensure sample stability.4.4. Experimental data were recorded by the fiber Bragg grating interrogator. Three PDMS samples per irradiation condition and dose were tested to minimize error. Error sources include intrinsic fiber variations.4.5. Tabular Data Description: Column 1: Temperature; Column 2: Bragg wavelength shift.4.6. Data Processing: Raw data consisted of Bragg center wavelengths for all FBGs recorded over time. A Python script was developed for data processing: data were normalized to the 20°C reference point. Bragg wavelength shifts at 30, 40, 50, and 60°C relative to 20°C were calculated by subtracting the center wavelength at 20°C. Linear relationships between Bragg wavelength shift and temperature were subsequently plotted.  5 Temperature Response Data of PDMS-Coated FBG Sensors5.1. Temperature response experiments were conducted on PDMS-coated FBG fibers subjected to different high-dose gamma irradiation levels using a temperature and humidity chamber and a Beijing Xizhu SuperHawk6000 fiber Bragg grating interrogator.5.2. Temperature Range: 20, 30, 40, 50, and 60°C, with a 20-minute stabilization period at each temperature.5.3. All sensors were laid flat in a plastic box to minimize potential micro-strain during handling and ensure stability.5.4. Experimental data were obtained from temperature response tests. Three PDMS samples per irradiation condition and dose were tested to minimize error. Error sources include intrinsic fiber variations and manual coating inconsistencies.5.5. Tabular Data Description: Column 1: Temperature; Column 2: Bragg wavelength shift.5.6. Data Processing: Raw data consisted of Bragg center wavelengths for all PDMS-coated FBG sensors recorded over time. A Python script was developed for data processing: data were normalized to the 20°C reference point. Bragg wavelength shifts at 30, 40, 50, and 60°C relative to 20°C were calculated by subtracting the center wavelength at 20°C. Linear relationships between Bragg wavelength shift and temperature were subsequently plotted.  6 Temperature Correction Algorithm Data6.1. A temperature correction method was applied to compensate for ambient temperature fluctuations during irradiation experiments. This involved performing linear fits on Bragg wavelength shift data collected one minute before and one minute after irradiation to establish a time-dependent linear response, which was used to correct the irradiation response. Environmental temperature stability was maintained by conducting experiments during periods of stable ambient temperature and using indoor air conditioning. Irradiation times were minimized to reduce interference from significant temperature variations.6.2. Tabular Data Description: Columns 1–3: Bragg wavelength shifts before, during, and after irradiation, respectively; Column 4: Irradiation time.*Reference: SEUNTJENS J, DUANE S. Photon absorbed dose standards[J/OL]. Metrologia, 2009, 46(2): S39-S58. DOI:10.1088/0026-1394/46/2/S04.  7 Radiation Response Sensitivity Enhancement Experimental Data for Sensors after High-Dose Gamma Pre-Irradiation7.1. Irradiation tests were performed using a VAREX IMAGING NDI-225-22 X-ray tube. The PDMS-coated FBG sensors under test were placed in a shielded irradiation chamber and connected via approximately 3 meters of standard single-mode fiber (SMF) to the fiber Bragg grating interrogator. The X-ray tube irradiated the sensors. Beam dose rates were calibrated using a Radcal ACCU-GOLD+ X-ray dosimetry system.7.2. For X-ray tube irradiation scenarios, each test group was repeated three times under constant temperature (15°C) and dose rate (6 Gy/min).7.3. Experimental Tabular Data: Columns 1–3: Bragg wavelength shifts (after data acquisition by the interrogator, Python preprocessing, and temperature correction) during irradiation for bare fiber, non-irradiated, and 100 kGy + vacuum-irradiated PDMS-coated FBG sensor groups, respectively; Column 4: Irradiation dose monitored by the ACCU-GOLD+ X-ray dosimetry system (gold standard).7.4. Error Sources: Intrinsic fiber variations and manual coating inconsistencies.  8 Environmental Temperature and Dose Rate Effects on Coated Fiber Radiation Response8.1. Irradiation tests were performed using a VAREX IMAGING NDI-225-22 X-ray tube. The PDMS-coated FBG sensors under test were placed in a shielded irradiation chamber and connected via approximately 3 meters of standard single-mode fiber (SMF) to the fiber Bragg grating interrogator. The X-ray tube irradiated the PDMS-coated FBG sensors. Three different irradiation conditions were established by adjusting tube voltage, tube current, and distance from the tube outlet for radiation monitoring purposes: 1) 3 Gy/min, 2) 6 Gy/min, 3) 9 Gy/min. Beam dose rates were calibrated using a Radcal ACCU-GOLD+ X-ray dosimetry system.8.2. Temperature Effect Experiment: Under X-ray tube irradiation at a constant dose rate of 6 Gy/min, ambient temperatures were set at 9°C, 10°C, and 25°C.8.3. Dose Rate Effect Experiment: Under X-ray tube irradiation at a constant ambient temperature of 20°C, dose rates were set at 3 Gy/min, 6 Gy/min, and 9 Gy/min.8.4. Experimental Tabular Data: Columns 1–3: Bragg wavelength shifts (after data acquisition by the interrogator, Python preprocessing, and temperature correction) during irradiation for PDMS-coated FBG sensors under different temperatures or different dose rates, respectively; Column 4: Irradiation dose monitored by the ACCU-GOLD+ X-ray dosimetry system (gold standard).8.5. Error Sources: Intrinsic fiber variations and manual coating inconsistencies.  9 Stability Experiment Data9.1. Irradiation tests were performed using a VAREX IMAGING NDI-225-22 X-ray tube. The PDMS-coated FBG sensors under test were placed in a shielded irradiation chamber and connected via approximately 3 meters of standard single-mode fiber (SMF) to the fiber Bragg grating interrogator. The X-ray tube irradiated the PDMS-coated FBG sensors. Beam dose rates were calibrated using a Radcal ACCU-GOLD+ X-ray dosimetry system.9.2. Continuous Irradiation Experiment: Ambient temperature 20°C, dose rate 6 Gy/min, continuous irradiation up to 200 Gy total dose.9.3. Cumulative X-ray Dose Response Over Several Months: Multiple irradiation experiments were conducted at different time points, under varying dose rates, ambient temperatures, and cumulative doses.9.4. Continuous Irradiation Experiment Tabular Data: Column 1: Bragg wavelength shifts (after data acquisition by the interrogator, Python preprocessing, and temperature correction) during irradiation for PDMS-coated FBG sensors at 6 Gy/min; Column 2: Irradiation dose monitored by the ACCU-GOLD+ X-ray dosimetry system (gold standard).9.5. Cumulative X-ray Dose Collection Experiment Over Several Months: Column 1: Radiation response coefficient at different cumulative doses; Column 2: Cumulative dose.9.6. Error Sources: Intrinsic fiber variations and manual coating inconsistencies.