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Description
The dosimetry characterization of a mobile electron-beam (EB) facility, tailored to treat industrial wastewater on site, is reported in this work. The accelerator operates at electron-beam energies of 500-700 keV and currents of 1-28 mA. The beam is magnetically scanned at 200 Hz to cover approximately 60 cm of a continuous water flow with a depth of 5 mm. Several well-established dosimeters are used: alanine pellets read with an electron paramagnetic resonance (EPR) spectrometer; cellulose triacetate (CTA) film read with a spectrophotometer; and a thin photodiode (SFH00206)-based dosimetry system operating in short-circuit current mode without an external applied voltage. In most dosimetry characterization, the dosimeters are conveyed through the irradiation field at 3 m/min, 12 cm beneath the scan window, to reproduce the wastewater irradiation condition. The facility's Operational Qualification is assessed in accordance with ISO/ASTM 51649 (2015). Different experimental approaches are used to measure the beam energy, beam width, surface dose uniformity at the center of the beam width, and beam length as a function of distance from the scan window. In-plant calibration curves are also obtained using alanine dosimeters for different electron-beam energies and dose rates. At the same beam energy, variations in dose rate are achieved by adjusting the beam current, and the resulting dose rate response is monitored online with a diode dosimeter. This enables the assessment of the beam length using a method recently proposed by our group. The results obtained with different dosimeters, essential for routine facility quality control, are compared using alanine as a reference standard. Good agreement is found among them, validating the overall dosimetry characterization of the EB facility.