Design and Characterisation of an Optical Fibre Dosimeter Based on Silica Optical Fibre and Scintillation Crystal

Abstract

In nuclear power plants, particle accelerators, and other nuclear facilities, measuring the level of ionising gamma radiation is critical for the safety and management of the operation and the environment’s protection. However, in many cases, it is impossible to monitor ionising radiation directly at the required location continuously. This is typically either due to the lack of space to accommodate the entire dosimeter or in environments with high ionising radiation activity, electromagnetic radiation, and temperature, which significantly shorten electronics’ lifetime. To allow for radiation measurement in such scenarios, we designed a fibre optic dosimeter that introduces an optical fibre link to deliver the scintillation radiation between the ionising radiation sensor and the detectors. The sensors can thus be placed in space-constrained and electronically hostile locations. We used silica optical fibres that withstand high radiation doses, high temperatures, and electromagnetic interference. We use a single photon counter and a photomultiplier to detect the transmitted scintillation radiation. We have shown that selected optical fibres, combined with different scintillation materials, are suitable for measuring gamma radiation levels in hundreds of kBq. We present the architecture of the dosimeter and its experimental characterisation with several combinations of optical fibres, detectors, and scintillation crystals.

Optical fibres for ionising radiation measurements

“…Then, one of the previously mentioned detectors can be used. Especially single photon counter which only provides information in the form of pulse count [2].…”

“…Teflon works perfectly as a mirror for light waves generated by LYSO crystal. This way, we can link more photons to fibre and reduce light loss [2]. The LYSO crystal is shown in Fig.…”

“…The overall design will provide a way to position the electronics away from radiation damage. As a result, we can measure high gamma radiation doses over long periods of time [1] [2].…”

Pmma Optical Fibre Irradiated With Co-60 for Optical Fibre Sensors

“…Figure 1. Ionising radiation measurement setup using * E-mail of the corresponding author -jelinmi@isibrno.cz optical fibre to transmit scintillation light from the scintillator to the photodetector [1].…”

“…Using a scintillation material that converts the incident radiation into visible light, which is then transmitted to an electronic detector through optical fibres, is shown in Figure 1 [1]. Even optical fibres that are used only for the transmission of scintillation radiation are exposed to a limited extent to the measured radiation.…”