Abstract
The focus of the present paper deals, for the first time, with commercial UV optical fibers, characterizing their behaviour as they are subjected to very high flux wiggler generated synchrotron radiation. Five distinct types of UV optical fibers, produced by three manufactures, were exposed to total doses between 5 Gy and 2000 Gy. The exposure to synchrotron radiation was performed in two campaigns. The tests were run off-line and considered the dependence of the radiation induced attenuation (RIA) as function of the total dose. The recovery of the radiation induced colour centres was studied at room temperature and after heating the samples up to 560 K. As a première, we also investigated through THz imaging and spectroscopy the irradiated optical fiber samples. Under these conditions, three of the optical fibers proved to be radiation resistant. The two optical fibers sensitive to synchrotron radiation exhibited a linear variation of the optical absorption at the wavelengths of λ = 229 nm, λ = 248 nm, and λ = 265 nm, for total doses between 60 Gy and 2000 Gy. These two samples showed also an increase of the optical absorption in the UV spectral range when heated to 560 K. The optical fibers sensitive to synchrotron radiation can potentially be used for on-line radiation dosimetry.
Highlights
Optical fibers were extensively tested under irradiation in order to assess their radiation resistance
We investigated the possible use of commercial available UV multimode optical fibers for radiation dosimetry, when they were irradiated with electron beam, gamma-ray, Bremsstrahlung or X-rays [19,20,21]
In our preliminary study we show that OFs at very high doses are giving promising results, but with a size of 400 micron of the core of the OFs, high resolution dosimetry in Microbeam Radiation Therapy (MRT) can’t be performed yet
Summary
Optical fibers were extensively tested under irradiation in order to assess their radiation resistance. There is no commercial on-line dosimeter to accurately perform absolute dose measurements or to determine the peak and the valley dose, when large factors between ~10-100 are required, with an excellent dynamic range, in the case involving the combination of dose rates of about 16 000 Gy/sec, a relatively low energy spectrum around 100 keV and, an optimal resolution of a few microns. For this reason a rather novel approach was tested at the ID17 Biomedical beamline to investigate the possible use of OF-based dosimeters. For the first time, according to our knowledge, irradiated optical fibers were studied by THz spectroscopy
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