Ce-doped SiO2 optical fibers for remote radiation sensing and measurement

Scintillating materials, able to convert energy of ionizing radiation into light in the visible-UV interval, are presently used in a wide class of applications such as medical imaging, industrial inspection, security controls and high energy physics detectors. In the last few years we studied and developed a new radiation sensor based on silica-glass fiber-optic technology. In its simplest configuration such device is composed by a short portion (about 10 mm) of scintillating fiber coupled to a photomultiplier through a suitably long passive silica fiber. In this work, we present new results concerning the characterization of silica based Ce and Eu doped fibers glasses obtained by a modified sol-gel method and drawn by a conventional drawing tower for optical fibers. The radio-luminescence of Eu doped fibers is rather weak; moreover it displays a marked sensitivity increase during subsequent irradiations, preventing the use of such fibers in dosimetry. On the other hand Ce-doped fibers show very high radiation hardness, signal stability and reproducibility, and high sensitivity to radiations with energies from 10 keV to several tens of MeV. Numerous tests with photons (X and gamma rays), electrons, and protons have already been successfully performed. At the early stage of its market introduction it is the smallest radiation sensor, also compared to MOSFET and diode technology and it appears to be the ideal choice for in vivo measurements in medical field or remote sensing.