Evaluation of a one-dimensional position-sensitive quartz optical fiber sensor based on the time-of-flight method for high radiation dose rate applications

Abstract

For the measurement of radiation distribution inside the Fukushima Daiichi Nuclear Power Station (FDNPS) buildings, the evaluation of a small-diameter quartz optical fiber as a one-dimensional position-sensitive sensor was conducted. The sensor determines the incident position of radiation into the fiber using the time-of-flight information from the Cerenkov photons generated in the optical fiber. Compared with a conventional sensor using plastic scintillating fiber, the quartz optical fiber has a much higher position resolution, which may be the result of the improvement of timing characteristics due to the prompt emission mechanism of the Cerenkov radiation. Additionally, the response of the quartz fiber sensor under high radiation field was evaluated. A count rate linearity up to a dose rate of at least 20 mSv/h was confirmed using a 10m-long quartz fiber with a diameter of 0.4 mm. Furthermore, the radiation tolerance of the sensor up to an accumulated dose of 1 kGy was evaluated.