Abstract
When optical fiber radiation measurements are applied
for a high dose rate area,
there has been a problem of radiation induced loss in the optical fibers.
In this study,
red and near infrared (IR) fluorescence from rare earth ions has been used
to reduce the problem.
From continuous measurements using Gd2O2S:Pr,
the superiority of using long wavelength emission has been shown.
Linear relation between dose rate and peak counts was confirmed and
it shows the possibility of using the long wavelength emission
for radiation measurements.
For calibration of the radiation induced loss,
the Optical Time Domain Reflectometry (OTDR) technique has been applied.
It has been shown that this method can broaden the dose rate limit
of the optical fiber based measurements.
Also, glass samples doped with rare-earth ions have been made and
irradiated by gamma rays.
Emission at longer wavelength than 700nm has been observed
for Eu3+ ions doped into silica,
fluorophosphate and ZBLAN glass samples.
Considering that it is easy to make silica glass and to connect it
to usual silica glass optical fiber,
silica glass doped with Eu3+ is thought to be
the most promising material for new scintillating fibers
with high radiation resistivity.