P. Polato

Development of a terbium-lithium glass for slow neutron detection

Abstract We have developed a new terbium-doped, lithium-loaded scintillating glass for slow neutron detection. This glass has the advantages of an emission spectrum with a maximum at 550 nm and of being drawn easily into optical fibers for the fabrication of scintillating optical fiber plates.

A new cerium scintillating glass for X-ray detection

Abstract We report the synthesis and the characterization of an improved cerium-activated scintillating glass suitable for X-ray imaging. 2 mm thick samples were tested under X-ray excitation and the results are compared with the ones reported for commercial glasses. The glass under investigation is approximately 30% more efficient under the irradiation of a radiological X-ray tube.

Optical, chemical and mechanical modifications induced by ion implantation on glass surfaces

Abstract Soda-lime glasses have been implanted with 50 keV Az ions. Modifications induced on the glass surface have been studied as a function of implanted dose, with particular regard to optical, chemical and mechanical properties. Optical measurements indicate a reduction of the refractive index, connected to the surface sodium content. The sodium profile has been measured using the Na23(p, α)Ne20 nuclear reaction. An improvement of the mechanical resistance has been observed at low implantation dose, together with a change of the chemical durability. An expansion of glass has been observed by S.E.M. and interpherometric microscopy for 80 keV implantation energy.

Preparation and characterization of Fe, Cr and Co oxide films on flat glass from gels

Abstract Iron, chromium and cobalt oxide films deposited on flat glass by pyrolysis of suitable compounds have been on the market for a long time. The purpose of the present investigation was to produce them by the gel method and to verify if a similar optical behaviour could be attained. One-component and multi-component coatings were obtained on a soda-lime glass; their oxide content was determined and their transmittance and reflectance were measured in the solar range. The sun-shielding performances obtained were generally lower than those provided by commercial sun-shielding glasses. A comparative analysis of the spectral behaviour in the visible range showed that the lower daylight-reflectances obtained for the dip coated plates can be explained mainly by the lower thicknesses obtained. However, the complex refractive indexes are also lower, possibly due to a less compact structure.

Radiation damage and annealing of scintillating glasses

Abstract Measurements of the radiation hardness, of cerium and terbium doped scintillating glasses, are reported in this work. Annealing tests have demonstrated the efficacy of violet-blue light in the repairing of radiation damage.

Radiation damage of silicate glasses doped with Tb3+ and Eu3+

Abstract In this work, we studied a set of Tb 3+ (or Eu 3+ ) doped silicate glasses in which some amounts of BaO were added to increase glass density. The irradiation-induced damage was investigated by absorbance measurements performed before and after each irradiation with doses ranging from 3 to 237 Gy. Analysed glasses underwent also light yield measurements investigated in terms of light production. The results showed that radiation damage and light yield depend on glass composition and are very low for the Eu 3+ containing glass and for the Tb 3+ activated glass which contains also lead. A possible explanation could be that lead and europium favour in the glass matrix the formation of a higher concentration of defects with respect to Tb 3+ doping ions.

Heavy metal fluoride glasses: modifications induced by ion implantation

Abstract Samples of fluorozircnate (ZBLAN) glasses were subjected to Argon irradiation at energies of 50 and 100 keV and a fluence of 5×1016 ions/cm2. The modifications induced by the implants were characterized by nuclear analysis (Rutherford backscattering), XPS, electron probe and optical techniques. Surface precipitation of metal species, as Zr and Ba, and F depletion are detected and a correlated increase of specular reflectivity was observed.

Colour centres induced by γ irradiation in scintillating glassy matrices for middle and low energy physics experiments

Abstract The effect of 60 Co irradiation (1–250 Gy) on the optical properties of selected phosphate and silicate-based scintillating glasses was investigated by transmission measurements performed at room temperature in the UV–Visible part of the spectra. Samples doped with rare-earth ions (Ce 3+ , Tb 3+ as emission centres, and Gd 3+ as an additional constituent in certain compositions) have been studied. The results are discussed taking into account the possible influence of different glass compositions on radiation induced colour centres.

Angular-dependent optical properties of coated glazings: validation of two predictive algorithms

The angular dependent optical properties of low-e and solar control glazings have been investigated in a European project, ADOPT, within the Standards Measurements and Testing programme. Two new predictive algorithms have been proposed and tested. One algorithm is based on an empirical formula and the other is based on a hybrid equivalent model, which approximates the actual coated glass. The validation procedure has included measurements as well as Fresnel calculations. The algorithms allow the user to calculate the solar heat gain coefficient versus angle of incidence for any transparent window combination without having to perform time-consuming measurements. For the tested window configurations the precision is mostly within one percentage point as compared to measured results.

Ion implantation effects in heavy metal fluoride glasses

Abstract Samples of a heavy metal fluoride glass (BInZnYbTGa) were subjected to argon and nitrogen irradiations of energies of 50 and 100 keV and fluences of 5×10 16 and 1×10 17 ions/cm 2 . A 10 keV Ar irradiation at the ion dose of 1×10 17 /cm 2 was also performed. Modifications induced by the implants were characterized by nuclear microanalysis, electron spectroscopy, scanning electron microscopy and optical techniques. Surface precipitation of Th and Ba, as well as F and In depletion, were detected. Correlated modifications of the optical transmittance and reflectance were observed.