Evaluation of silica and PMMA optical fibre response when irradiated with 16.5 MeV protons

• Published in: Physica medica Vol. 65; pp. 15 - 20
• Main Authors: Asp, Johan, Caraça Santos, Alexandre M., Afshar V., Shahraam, Qi Zhang, Wen, Bezak, Eva
• Format: Journal Article
• Language: English
• Published: Italy Elsevier Ltd 01.09.2019
• Subjects: Fibre optic luminescence dosimetry; Optical Fibers; Polymethyl Methacrylate; Protons; Radioluminescence; Silicon Dioxide; Spectrum Analysis; Protons; Fibre optic luminescence dosimetry; Radioluminescence
• ISSN: 1120-1797; 1724-191X
• DOI: 10.1016/j.ejmp.2019.08.001

•The response of a PMMA and silica optical fibre when exposed to 16.5 MeV protons is investigated.•A linear response observed in the change in ratio between the 460 nm and 650 nm peaks of the silica fibre.•Changes in PMMA emission spectrum are shown to be due to activation and photodarkening within the fibre. An investigation into the response of optical fibres to 16.5 MeV protons is presented here. A silica and a poly(methyl methacrylate) (PMMA) optical fibre was exposed to 16.5 MeV protons from a GE PETtrace cyclotron. The optical fibres were exposed to beam currents of 30nA – 270nA and the emission spectrum analysed. The silica fibre was the most sensitive and had two main peaks at 460 nm and 650 nm. The ratio between the peaks was observed to increase as irradiation of the fibres continued, where the 460 nm peak increased at a rate >4 times the 650 nm peak. The rate of increase of the ratio between the peaks was observed to be constant at a constant target current and linear with target current. In the case of the PMMA fibre, significant spectral changes were observed during the exposure to 16.5 MeV protons. A simple method for estimating the effect of photodarkening and activation is presented here and indicated that the changes in the spectrum for the PMMA fibres may be due to photodarkening and activation.