Thermally stimulated luminescence of Ce and Tb doped SiO2 sol–gel glasses

Phys. Status Solidi (c)

Martini

et al. 2007

Self Cite

Phosphorescence emitted by a new dosimetric system based on a SiO 2 optical fibre doped with Ce 3+ ions was investigated. The defects in the matrix that, acting as electron traps, originate the phosphorescence signal were studied by means of thermally stimulated luminescence in the temperature interval 313-533 K. A continuous trap distribution with activation energies extending from 0.8 to 1.5 eV was observed. On the basis of these findings, the temperature dependence of the shape of isothermal phosphorescence decay was analysed and the corresponding spectrum was compared with that of radioluminescence.1 Introduction Optical fibres, allowing a remote and real time radiation monitoring, are useful for a prompt evaluation of the dose rate in hazardous locations interested by high radiation fields. For such reason, optical fibres can be also employed in radiation therapy applications as in vivo dosimeter [1,2]. A prototype of a new system based on a Ce 3+ -doped optical fibre was recently developed, and its dosimetric properties were tested using both photon fields of low energies produced by an X-ray tube [3], and more energetic photon and electron beams produced by a medical linear accelerator commonly used for radiation therapy treatments [4]. The response of the system showed a good reproducibility, linearity with increasing dose and dose rate, and a satisfactory independence of radiation energy. By contrast, further investigations and improvements in the luminescence properties of the device are deserved, in particular regarding the presence of a slow phosphorescence component [4].The aim of this work is the investigation of the origins of such phosphorescence and its characterization. The defects in the Ce-doped glass are therefore studied by means of thermally stimulated luminescence (TSL) measurements on the active fibre, and the results are compared with the corresponding ones available on its parent bulk material [5]. The results of the trap parameters analysis are then discussed in relation to the measurements of isothermal phosphorescence decay performed on the Ce 3+ -doped optical fibre.

Section: Conclusion Phosphorescence Of Sio 2 Optical Fibre Doped Witsupporting

confidence: 69%

Section: Radioluminescence Measurements and Isothermal Phosphorescencsupporting

confidence: 55%

mentioning

confidence: 99%

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Phosphorescence of SiO₂ optical fibres doped with Ce³⁺ ions

Veronese

Phys. Status Solidi (c)

Martini

et al. 2007

Self Cite

“…Such behavior is in agreement with the presence of several trap levels exhibiting also inhomogeneous broadening. Broad distributions of trap energy levels are commonly detected in glasses [32,33]. Once more, comparing all samples and taking into account their positions (Fig.…”

Section: Rl Hysteresis and Tsl Glow Curvesmentioning

confidence: 97%

Optical properties and radiation hardness of Pr-doped sol-gel silica: Influence of fiber drawing process

Cova

Journal of Luminescence

Moretti

et al. 2017

Optical properties and radiation hardness of Pr-doped sol-gel silica: Influence of fiber drawing process (2017) J. Lumin, vol. 192, p. 661-667 doi: 10.1016Lumin, vol. 192, p. 661-667 doi: 10. /j.jlumin.2017 Publisher's version of the article can be found at the following site: http://www.sciencedirect.com/science/article/pii/S0022231317307949 A complete and detailed characterization of the optical, scintillation and radiation hardness properties of Pr-doped silica is carried out employing different experimental techniques including steady-state and time-resolved photo-luminescence, radio-and thermo-luminescence, scintillation and optical absorption.Optical absorption measurements, performed after X-ray irradiation sequences up to 1 kGy, evidence the formation of radiation-induced absorption bands related to point defects acting as color centers. Spontaneous partial recovery of the radiation-induced defects at room temperature, as well as after thermal treatments, is also disclosed.Particular attention is paid to the comparison between bulk silica, both before and after a melting process, and fibers. The results reveal the presence of a lower concentration of optically active defects in melted glass. Such comparison highlights a role of the fiber drawing in modifying the glass defectiveness, consisting in the occurrence of a structural reorganization of the amorphous network during the process.

“…In this paper, we propose a novel type of glass composite fiber dosimeter based on the RL emission of a small portion of glass fiber doped with Cerium. Previous investigations already demonstrated the interesting RL properties of these composite fibers [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Moreover, with the aim to better separate the Cherenkov emission from the scintillating signal [36,37] an alternative Eu doped fiber was produced, tested and compared with Ce-doped ones.…”

Section: Introductionmentioning

confidence: 99%

Ce-doped SiO 2 optical fibers for remote radiation sensing and measurement

Chiodini

Vedda

Fiber Optic Sensors and Applications VI

et al. 2009

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 radioluminescence 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.