Optical Fiber-Based Monitoring of X-ray Pulse Series from a Linear Accelerator

Mohamed Bouazaoui,Jeoffray Vidalot,Hicham El Hamzaoui,Geraud Bouwmans,Youcef Ouerdane,Sylvain Girard,Bruno Capoen,Philippe Paillet,Adriana Morana,Andy Cassez,Aziz Boukenter,Marc Gaillardin

doi:10.3390/radiation2010002

Abstract

We investigated in this work the radioluminescence properties of a Ce-doped multimode silica-based optical fiber (core diameter of 50 µm) manufactured by the sol–gel technique when exposed to the high-energy X-rays (~600 keV) of the ORIATRON facility of CEA. We demonstrated its potential to monitor in real-time the beam characteristics of this facility that can either operate in a pulsed regime (pulse duration of 4.8 µs, maximum repetition rate of 250 Hz) or in a quasi-continuous mode. The radiation-induced emission (radioluminescence and a minor Cerenkov contribution) linearly grew with the dose rate in the 15–130 mGy(SiO2)/s range, and the afterglow measured after each pulse was sufficiently limited to allow a clear measurement of pulse trains. A sensor with ~11 cm of sensitive Ce-doped fiber spliced to rad-hard fluorine-doped optical fiber, for the emitted light transport to the photomultiplier tube, exhibited interesting beam monitoring performance, even if the Cerenkov emission in the transport fiber was also considered (~5% of the signal). The beam monitoring potential of this class of optical fiber was demonstrated for such facilities and the possibilities of extending the dose rate range are discussed based on possible architecture choices such as fiber type, length or size.

Highlights

A variety of radiation sources have been developed these last decades to satisfy the diversity of applications exploiting radiation–matter interactions
The high energy physics facilities or the space industry need to perform radiation ageing and radiation testing of electronic components [2,3] to predict the cumulative dose effects on their performance and to imagine ways to improve their radiation tolerance. Both transient and steady state tests are carried out to understand the effects of dose rate and cumulated dose regarding medical applications
By considering the different locations of the radiation-hardened fluorinecladding doped fiber (RHF) and the Ce-fiber within the beam, the dose rates used for the sole RHF Radiation 2022, 2, FOR PEER REVIEWwere considered at 90% of the total dose rate

Summary

Introduction

A variety of radiation sources have been developed these last decades to satisfy the diversity of applications exploiting radiation–matter interactions. Therapies using radiation to cure tumor cells are continuously improved for patient benefit, and today a lot of research is in progress to assess the potential of pulsed beams for FLASH therapy [4] All of these tools need dosimetry systems to accurately measure the deposited energy to ensure the highest treatment efficiency. The Cerenkov photon production depends on the particle flux and is exactly synchronized with the irradiation It could be exploited for specific radiation detection applications, such as in medicine [32]. We evaluated the performance of a sensing probe consisting in a short length of Ce-doped optical fiber (50 μm core diameter) spliced to a radiation-resistant transport F-doped fiber We show that this probe allowed the real-time monitoring of pulsed or quasi-continuous X-ray beams. Thanks to the fast time decay of the Ce3+ ions luminescence, this sensor can count the pulse number and provide the dose per pulse

Irradiation Facility Description

Description of the Fiber‐Based Sensor

Experimental Procedure

RIE versus Dose Rate Experiments

Correlation between RIE Plateau and Dose Rates

Extension of the Dose Rate Range