Kulwant Singh Thind

Gamma-ray attenuation coefficients in some heavy metal oxide borate glasses at 662 keV

Abstract The linear attenuation coefficient (μ) and mass attenuation coefficients ( μ ϱ ) of glasses in three systems: xPbO(1 − x)B2O3, 0.25PbO · xCdO(0.75 − x)B2O3 and xBi2O3(1 − x)B2O3 were measured at 662 keV. Appreciable variations were noted in the attenuation coefficients due to changes in the chemical composition of glasses. In addition to this, absorption cross-sections per atom were also calculated. A comparison of shielding properties of these glasses with standard shielding materials like lead, lead glass and concrete has proven that these glasses have a potential application as transparent radiation shielding.

Effect of Nd3 + concentration on the physical and absorption properties of sodium-lead-borate glasses

The effect of increasing the rare earth ion concentration on the physical and spectroscopic properties of Nd3 + doped sodium-lead-borate glasses have been studied for the compositions (10-x) Na2O-30PbO-60B2O3-xNd2O3, where x = 1.00, 1.25, 1.50, 1.75 and 2.00 mol %. Optical band gaps, cut-off wavelengths and various spectroscopic parameters (E1, E2, E3, F2, F4, F6 and x4f) have been determined from the room temperature absorption spectra. Judd-Ofelt theory has been employed to determine the intensity parameters W2, W4 and W6 which in turn are used to evaluate radiative transition probability (A), branching ratio (b) and radiative lifetime (tR) for the fluorescent level 4F3 / 2. The W2 parameter and hence the non-symmetric component of electric field acting on Nd3 + ion is found to be highest for glass with 1.75 mol% of Nd2O3. Because of the poor resolution of hypersensitive transition, the covalency of the Nd-O bond has been characterized by the relative intensity of 4I9 / 2 ®4F7 / 2, 4S3 / 2. The highest covalency has been predicted for glass with 2 mol% Nd2O3. The radiative properties are found to improve with an increase in concentration of Nd2O3 for the present study.

The effective atomic number revisited in the light of modern photon-interaction cross-section databases.

The effective atomic number, Z(eff), has been calculated for fatty acids and cysteine. It is shown that Z(eff) is a useful parameter for low-Z materials at any energy above 1 keV. Absorption edges of medium-Z elements may complicate the energy dependence of Z(eff) below 10 keV. The notion of Z(eff) is perhaps most useful at energies where Compton scattering is dominating, and where Z(eff) is equal to the mean atomic number, Z, over a wide energy range around 1 MeV.

Optical properties of alkali and alkaline-earth lead borate glasses doped with Nd3+ Ions

Spectroscopic and physical properties of Nd3+-doped alkali lead borate glasses of type 20R2O · 30PbO · 49.5B2O3 · 0.5Nd2O3 (R = Li and K) and alkaline-earth lead borate glasses 20RO · 30PbO · 49.5B2O3 · 0.5Nd2O3 (R = Ca, Ba, and Pb) have been investigated. Optical absorption spectra have been used to determine the Slater-Condon (F2, F4, and F6), spin orbit ξ4f, and Racah parameters (E1, E2, and E3). The oscillator strengths and the intensity parameters Ω2, Ω4, and Ω6 have been determined by the Judd-Ofelt theory, which, in turn, provide the radiative transition probability (A), total transition probability (AT), radiative lifetime (τR), and branching ratio (βR, %) for the fluorescent levels. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω4/Ω6), the value of which is in the range 0.2–1.5, typical of Nd3+ in different laser hosts. A red shift of the peak wavelength is observed upon addition of alkali or alkaline-earth oxides to the lead borate glass. A higher value of the W2 parameter for potassium-doped glass indicates a higher covalency for this glass matrix. The relative intensity of the peaks 4I9/2 → 4F7/2, 4S3/2 has also been studied.

Studies on Effective Atomic Numbers and Electron Densities in Some Commonly Used Solvents

Abstract The effective atomic numbers and the electron densities of some commonly used solvents, i.e., ethanol, methanol, propanol, butanol, water, toluene, benzene, carbontetrachloride, acetonitrile, chlorobenzene, diethylether, and dioxane at the energies 279, 356, 662, 1173, and 1332 keV were calculated by using the measured mass attenuation coefficients in a well-collimated narrow beam transmission geometry. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

Composition dependent spectroscopic properties of Nd3+ doped sodium lead borate glasses

Nd3+ doped oxide glasses of the type xNa2O–30 PbO–(69.5-x) B2O3–0.5Nd2O3 were prepared and investigated for physical and spectroscopic properties. Optical absorption spectra and Judd-Ofelt theory has been used to determine the oscillator strengths and the intensity parameters Ωλ (λ=2, 4, 6). The radiative transition probability (A), radiative lifetime (τR) and branching ratio (βR) for the fluorescent levels of Nd3+ in the prepared glasses have been determined. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω4 / Ω6), the value of which is in the range 0.2-1.5, typical for Nd3+ in different laser hosts. The radiative transition probability of the potential lasing transition 4F3/2 → 4I11/2 of Nd3+ ions is found to increase with increase in content of Na2O.

Two Media Method: An Alternative Methodology for the Measurement of Attenuation Coefficients of Irregularly Shaped Samples

Abstract The two media method used to determine the linear attenuation coefficients of irregularly shaped samples without the knowledge of the thickness of the sample has been verified. The linear attenuation coefficient values of regularly and irregularly shaped flyash material samples have been measured by the two media method using five different materials as media. The obtained values of the linear attenuation coefficient were compared with the results of the standard narrow beam gamma-ray transmission method. The results were in good agreement.