الفهرس 
Introduction to radiationOnly 14 pages are availabe for public view
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Abstract
In the present dissertation, borosilicate glass systems containing two different heavy metal oxides were studied. Sodium borosilicate glass system containing PbO in the range from 20 up to 60 mol % was prepared and then a small amount of B2O3 was replaced by an equivalent part of gadolinium oxide to investigate the relevant impact. The composition containing 30 mol % of PbO was selected to be blended by Gd2O3 for structural considerations. The investigated samples were prepared using the normal melt quench technique. The structural properties of the prepared samples were characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), density and its related parameters. The XRD patterns confirm the amorphous nature for both glass systems. The density results and its related parameters for both systems have been found to be compositional dependent. The FTIR deconvolution results showed BO3 to BO4 ratio has a vigorous variant trend for both systems. The structural properties showed formation of non-bridging oxygen of the prepared glasses. The measurements showed that lead oxide has dual role in the glass network while gadolinium only acts as a modifier oxide. A series of optical measurements at normal incidence were measured in the spectral range of 200–1200 nm. Analysis of the optical data reveals the compositional dependence of the optical parameters, such as cutoff wavelength (λ_Cutoff), optical band gap (E_g) and refractive index (n). The red shift in cutoff wavelength was attributed to the formation of non-bridging oxygen. The variation of optical band gap and refractive index was correlated to the impact of the heavy metals on the structure. The attenuation capability of different gamma ray energies and neutrons in the glass system was investigated. Gamma-ray attenuation measurements were performed using a 2//× 2// NaI(Tl) scintillation detectors. The experimental linear attenuation coefficients (μ) were obtained using transmitted beam method, and the experimental mass attenuation coefficients (σ_(Exp.) ) were estimated and compared with the calculated one (σ_(Theo.) ) which are carried out using WinXCom computer program (version 3.1). The effect of the the studied heavy metals on the attenuation results of gamma rays was quite clear throughout the increment of the attenuation coefficients. Additionally, good agreement was observed between experimental and calculated data.
The macroscopic fast neutron removal cross-sections (Σ_F ) have been calculated using MERCSF - N computer program based on mixture rule. In both systems, it is observed that the neutron was slowed down via elastic scattering. This was detected from the increase of fast neutron attenuation with the increase of boron nuclei.
Neutron spectra emitted from 241Am-Be radioactive source (5 Ci A) with neutron output of (1.1-1.4) x 107 n/s were used to measure the slow neutron removal cross sections (Σ_S ) for all the studied glasses. The neutron
transmitted beam was measured using He-3 counter under good geometry conditions. The transmitted beam was used to plot attenuation relations which are used to calculate the macroscopic removal cross sections of slow neutrons (ΣS). It was observed that the increment of boron content in the first system enhanced effectively the attenuation process of slow neutrons. On the other hand, in the second system, gadolinium has a superior effect in this regard. This behavior was attributed to the higher capture slow neutron cross section of both boron and gadolinium nuclei.
The obtained results reveal that the investigated glass systems represents proper shielding materials in the nuclear domain.
Keywords: Glass materials, Heavy metal and rare earth oxides glass, Structural, Optical and attenuation properties, Neutrons, Gamma rays.