Total Mass Attenuation Coefficients Research Articles

Study of mass attenuation coefficients, effective atomic numbers and electron densities for some low Z compounds of dosimetry interest at 59.54 keV incident photon energy

Total mass attenuation coefficient, total photon interaction cross-section, effective atomic numbers (Zeff) and electron densities (Ne) of Aniline (C6H5NH2), Cyclohexane (C6H12), Glycerine (C3H5(OH)3), Butyl alcohol N-(C4H9OH), DMSO – dimethyl sulfoxide (C2H6OS), Methyl ethyl-ketone (C4H8O), Xylene (C8H10), Acetophenone (C8H8O) and Triethyl amine (C6H15N) have been measured at 59.54keV energy photon emitted by 100mCi 241Am point source employing narrow beam transmission geometry. Obtained results have been compared with theoretically calculated values of XCOM (Berger and Hubbel, 1987) and FFAST (Chantler et al., 2005). Mixture rule was employed to calculated theoretical mass attenuation coefficient values for each sample. Good agreement has been observed between experimental and theoretical values within experimental uncertainties.

Effective atomic numbers, electron densities, and tissue equivalence of some gases and mixtures for dosimetry of radiation detectors

Total mass attenuation coefficients, ?m, effective atomic number, Zeff, and effective electron density, Neff, of different gases - carbon dioxide, methane, acetylene, propane, butane, and pentane used in radiation detectors, have been calculated for the photon energy of 1 keV to 100 GeV. Each gas has constant Zeff values between 0.10 to 10 MeV photon energies; however, these values are way far away from ICRU tissue. Carbon dioxide gas shows the closest tissue equivalence in the entire photon energy spectrum. Relative tissue equivalences of the mixtures of gases with respect to ICRU tissue are in the range of 0.998-1.041 for air, argon (4.5%) + methane (95.5%), argon (0.5%) + carbon dioxide (99.5%), and nitrogen (5%) + methane (7%) + carbon dioxide (88%). The gas composition of xenon (0.5%) + carbon dioxide (99.5%) shows 1.605 times higher tissue equivalence compared to the ICRU tissue. The investigated photon interaction parameters are useful for exposure and energy absorption buildup factors calculation and design, and fabrication of gaseous detectors for ambient radiation measurement by the Geiger-Muller detector, ionization chambers and proportional counters.

Effect of BaO on Optical, Physical and Radiation Shielding Properties of SiO2-B2O3-Al2O3-CaO-Na2O Glasses System

In this work, the effect of BaO on optical, physical and radiation shielding properties of SiO2-15B2O3-2Al2O3- 10CaO-23Na2O glasses have been investigated. Glasses in composition (50-x)SiO2:15B2O3:2Al2O3:10CaO:23Na2O: xBaO, where x = 0, 5, 10, 15 and 20% mol were fabricated by melt-quenching technique. The results found that, the density and molar volume of glasses were increased with increasing of BaO concentration. The optical spectra were measured by uv-visible spectrophotometer and show shifted to longer wavelength. Gamma-ray shielding properties at 662 keV of SiO2-B2O-2Al2O3-10CaO-23Na2O-BaO glasses have been studied. The experimental results showed good agreement with the theoretical values, calculated by WinXCom. Moreover, the comparison of ordinary concrete and commercial window in term of half value layer has been investigated and show better radiation shielding properties with advantage of being transparent to visible light. From the theoretical calculation, the Compton scattering gives dominant contribution to the total mass attenuation coefficients for all studied glass samples.

Scintillation response of Lu1.95Y0.05SiO5:Ce and Y2SiO5:Ce single crystal scintillators

The scintillation response of the new cerium-doped rare-earth scintillator lutetium–yttrium oxyorthosilicate (Lu1.95Y0.05SiO5:Ce, LYSO:Ce) were investigated and compared to those of cerium-doped yttrium oxyorthosilicate (Y2SiO5:Ce, YSO:Ce) crystal. The light yield and energy resolution were measured using photomultiplier tube (PMT) readout. The non-proportionality of the light yield and energy resolution versus γ-ray energy were measured and the intrinsic resolution of the crystals was calculated. For 662keV γ-rays (137Cs source), LYSO:Ce showed a light yield of 37,400±3700ph/MeV, which is much higher than that of 26,300±2600 ph/MeV obtained for YSO:Ce. The energy resolution of 6.8±0.2% obtained with YSO:Ce is better than that of 7.7±0.2% obtained with LYSO:Ce, due to its better intrinsic resolution and proportionality in light yield. The photofraction was determined for both crystals and compared with the cross-sections ratio calculated using WinXCom program. The experimental results of the total mass attenuation coefficients for both crystals are in good agreement with the theoretical values, within the experimental uncertainty.

Gamma ray and neutron shielding properties of some concrete materials

Shielding of gamma-rays and neutrons by 12 concrete samples with and without mineral additives has been studied. The total mass attenuation and linear attenuation coefficients, half-value thicknesses, effective atomic numbers, effective electron densities and atomic cross-sections at photons energies of 59.5 and 661 keV have been measured and calculated. The measured and calculated values were compared and a reasonable agreement has been observed. Also the recorded values showed a change with energy and composition of the concrete samples. In addition, neutron shielding has been treated in terms of macroscopic removal cross-section (Σ R, cm −1) concept. The WinXCom and NXcom programs were employed to calculate the attenuation coefficients of gamma-rays and neutrons, respectively.

The determination of the total mass attenuation coefficients and the effective atomic numbers for concentrated colemanite and Emet colemanite clay

In this study, the attitude of some photon absorption energy related parameters such as coherent, Compton, photoelectric, pair-nuclear, pair-electronic, the total mass attenuation coefficients, effective atomic number, and electron density are investigated for two the mixtures, concentrated colemanite and Emet colemanite clay. In order to reach some desired conclusions, we calculated many of these parameters ranging from low energy (1 keV) to high energy (100 MeV) by using WinXCom program. Radiation shielding of the materials are compared in terms of B 2O 3 content. One of the most significant promise claimed by this study is that the excess or scarcity of B 2O 3 content in any material may not be a defining parameter alone for environment, construction, radiation shielding, and neutron capture applications. As well as B 2O 3 content, concentration values from quantitative and qualitative analysis of other compounds such as SiO 2, CaO, MgO, Fe 2O 3, Al 2O 3, PbO, K 2O contained in a material, if existed, must be taken into account.

Determination of mass attenuation coefficients, effective atomic and electron numbers, mean free paths and kermas for PbO, barite and some boron ores

The total mass attenuation coefficients, μ m , for PbO, barite, colemanite, tincal and ulexite were determined at 80.1, 302.9, 356.0, 661.7 and 1250.0 keV photon energies by using NaI (Tl) scintillation detector. Effective atomic number, Z eff , effective electron number, N eff , total atomic cross-section, σ t , total electronic cross-section, σ e , mean free path, mfp, and kerma relative to air were determined experimentally and theoretically. The theoretical mass attenuation coefficients were estimated using mixture rule. The calculated values were compared with the experimental values for all samples.

Studies on effective atomic numbers and electron densities in different solid state track detectors in the energy range 1 keV–100 GeV

The total mass attenuation coefficients, effective atomic numbers and electron densities of different types of solid state track detectors have been calculated for total and partial photon interactions in the wide energy range of 1 keV–100 GeV using WinXCom program. The values of these parameters have been found to vary with photon energy and chemical composition of the detectors. The variations of these parameters with energy are shown graphically for all photon interactions. The results of this work can stimulate research for other detectors and different materials.

Comparative study of silicate glasses containing Bi 2O 3, PbO and BaO: Radiation shielding and optical properties

The radiation shielding and optical properties of xBi 2O 3:(100- x)SiO 2, xPbO:(100- x)SiO 2 and xBaO:(100- x)SiO 2 glass systems (where 30 ⩽ x ⩽ 70 is the composition by weight%) have been investigated. Total mass attenuation coefficients ( μ m ) of glasses at 662 keV were improved by increasing their Bi 2O 3 and PbO content, which raised the photoelectric absorption in glass matrices. Raising the BaO content to the same fraction range, however, brought no significant change to μ m . These results indicate that photon is strongly attenuated in Bi 2O 3 and PbO containing glasses, and but not in BaO containing glass. The results from the optical absorption spectra show an edge that was not sharply defined; clearly indicating the amorphous nature of glass samples. It is observed that the cutoff wavelength for Bi 2O 3 containing glass was longer than PbO and BaO containing glasses.

Mass attenuation coefficients of B2O3–Al2O3–SiO2–CaF2 glass system at 0.662 and 1.25 MeV gamma energies

The total mass attenuation coefficients, partial interaction and the effective atomic numbers (Zeff) of glass system (80−x)B2O3–10Al2O3–10SiO2–xCaF2 (where x = 5, 10, 20, 25, 30, 35 and 40 mol %) have been calculated at photon energies 0.662 and 1.25 MeV using the WinXCom software on the basis of mixture rule. Results indicated that the total mass attenuation coefficients showed a decrease with increasing the CaF2 concentration, due to a decrease in Compton scattering probability, which gave a dominant contribution to the total mass attenuation coefficients for the studied glass samples at both energies. However, the photoelectric absorption and coherent scattering showed an increase with increasing the CaF2, concentrations at same energies. For a comparison, the total mass attenuation coefficients of the glass system had lower values at the energy 1.25 MeV than that at 0.662 MeV. Zeff was found to increase linearly with the increase of CaF2 concentrations. It was concluded that low CaF2 concentrations in glass system, under study, have Zeff close to that of human tissue and have higher total absorption coefficients at energy of 0.662 MeV than that at 1.25 MeV. These results are very useful in designing gamma radiation detectors using thermoluminescence technique. Therefore, it is recommended to use low CaF2 concentration of our glass system as good gamma detectors at energy of 1.25 MeV.

Total mass attenuation coefficient evaluation of ten materials commonly used to simulate human tissue

To study the doses received by patient submitted to ionizing radiation, several materials are used to simulate the human tissue and organs. The total mass attenuation coefficient is a reasonable way for evaluating the usage in dosimetry of these materials. The total mass attenuation coefficient is determined by photon energy and constituent elements of the material. Currently, the human phantoms are composed by a unique material that presents characteristics similar to the mean proprieties of the different tissues within the region. Therefore, the phantoms are usually homogeneous and filled with a material similar to soft tissue. We studied ten materials used as soft tissue-simulating. These materials were named: bolus, nylon®, orange articulation wax, red articulation wax, PMMA, modelling clay, bee wax, paraffin 1, paraffin 2 and pitch. The objective of this study was to verify the best material to simulate the human cerebral tissue. We determined the elementary composition, mass density and, therefore, calculated the total mass attenuation coefficient of each material. The results were compared to the values established by the International Commission on Radiation Units and Measurements - ICRU, report n° 44, and by the International Commission on Radiation Protection - ICRP, report n° 89, to determine the best material for this energy interval. These results indicate that new head phantoms can be constructed with nylon®.

Comparison of some lead and non-lead based glass systems, standard shielding concretes and commercial window glasses in terms of shielding parameters in the energy region of 1 keV–100 GeV: A comparative study

The effective atomic numbers, Z eff of some glass systems with and without Pb have been calculated in the energy region of 1 keV–100 GeV including the K absorption edges of high Z elements present in the glass. Also, these glass systems have been compared with some standard shielding concretes and commercial window glasses in terms of mean free paths and total mass attenuation coefficients in the continuous energy range. Comparisons with experiments were also provided wherever possible for glasses. It has been observed that the glass systems without Pb have higher values of Z eff than that of Pb based glasses at some high energy regions even if they have lower mean atomic numbers than Pb based glasses. When compared with some standard shielding concretes and commercial window glasses, generally it has been shown that the given glass systems have superior properties than concretes and window glasses with respect to the radiation-shielding properties, thus confirming the availability of using these glasses as substitutes for some shielding concretes and commercial window glasses to improve radiation-shielding properties in the continuous energy region.

Evaluation of tissue-equivalent materials to be used as human brain tissue substitute in dosimetry for diagnostic radiology

Abstract Tissue-equivalent materials to be used as substitutes for human brain tissue in dosimetry for diagnostic radiology have been investigated in terms of calculated total mass attenuation coefficient (μ/ρ), calculated mass energy-absorption coefficient (μen/ρ) and absorbed dose. Measured linear attenuation coefficients (μ) have been used for benchmarking the calculated total mass attenuation coefficient (μ/ρ). The materials examined were bolus, nylon®, orange articulation wax, red articulation wax, PMMA (polymethylmethacrylate), bees wax, paraffin I, paraffin II, pitch and water. The results show that water is the best substitute for brain among the materials investigated. The average percentage differences between the calculated μ/ρ and μen/ρ coefficients for water and those for brain were 1.0% and 2.5%, respectively. Absorbed doses determined by Monte Carlo methods confirm water as being the best brain substitute to be used in dosimetry for diagnostic radiology, showing maximum difference of 0.01%. Additionally this study showed that PMMA, a material often used for the manufacturing of head phantoms for computed tomography, cannot be considered to be a suitable substitute for human brain tissue in dosimetry.

A novel shielding material prepared from solid waste containing lead for gamma ray

Human beings are continuously exposed to cosmogenic radiation and its products in the atmosphere from naturally occurring radioactive materials (NORM) within Earth, their bodies, houses and foods. Especially, for the radiation protection environments where high ionizing radiation levels appear should be shielded. Generally, different materials are used for the radiation shielding in different areas and for different situations. In this study, a novel shielding material produced by a metallurgical solid waste containing lead was analyzed as shielding material for gamma radiation. The photon total mass attenuation coefficients ( μ/ ρ) were measured and calculated using WinXCom computer code for the novel shielding material, concrete and lead. Theoretical and experimental values of total mass attenuation coefficient of the each studied sample were compared. Consequently, a new shielding material prepared from the solid waste containing lead could be preferred for buildings as shielding materials against gamma radiation.

Radiation shielding of concretes containing different lime/silica ratios

The shielding of γ-rays and fast neutrons by concrete has been studied for concretes containing different lime/silica ratios. Calculations were carried out for six different concrete samples. The total mass attenuation coefficients ( μ/ ρ, cm 2 g −1) have been computed at photon energies of 1 keV to 100 GeV using the personal computer software package WinXCom. Also the macroscopic effective fast neutron removal cross-sections (Σ R , cm −1) have been calculated using MERCSF-N program and the removal cross-section database for all required elements. The obtained results showed that the lime/silica ratio of concrete has significant and insignificant effects on μ/ ρ and Σ R values, respectively.

Chemical composition, effective atomic number and electron density study of trommel sieve waste (TSW), Portland cement, lime, pointing and their admixtures with TSW in different proportions

The trommel sieve waste (TSW) which forms during the boron ore production is considered to be a promising building material with its use as an admixture with Portland cement and is considered to be an alternative radiation shielding material, also. Thus, having knowledge on the chemical composition and radiation interaction properties of TSW as compared to other building materials is of importance. In the present study, chemical compositions of the materials used have been determined using a wavelength dispersive X-ray fluorescence spectrometer (WDXRFS). Also, TSW, some commonly used building materials (Portland cement, lime and pointing) and their admixtures with TSW have been investigated in terms of total mass attenuation coefficients (mu/rho), photon interaction cross sections (sigma(t)), effective atomic numbers (Z(eff)) and effective electron densities (N(e)) by using X-rays at 22.1, 25keV and gamma-rays at 88keV photon energies. Possible conclusions were drawn with respect to the variations in photon energy and chemical composition.

Study on borate glass system containing with Bi2O3 and BaO for gamma-rays shielding materials: Comparison with PbO

Abstract In this work, the mass attenuation coefficients and shielding parameters of borate glass matrices containing with Bi 2 O 3 and BaO have been investigated at 662 keV, and compare with PbO in same glass structure. The theoretical values were calculated by WinXCom software and compare with experiential data. The results found that the mass attenuation coefficients were increased with increasing of Bi 2 O 3 , BaO and PbO concentration, due to increase photoelectric absorption of all glass samples. However, Compton scattering gives dominant contribution to the total mass attenuation coefficients for studied glass samples. Moreover the half value layers (HVL) of glass samples were also better than ordinary concretes and commercial window glass. These results reflecting that the Bi-based glass can use replace Pb in radiation shielding glass. In the case of Ba, may be can use at appropriate energy such as X-rays or lower.

Studies on effective atomic numbers, electron densities and mass attenuation coefficients in Au alloys

The total mass attenuation coefficients (mu/rho) for pure Au and Au99Be1, Au88Ge12, Au95Zn5 alloys were measured at 59.5 and 88.0 keV photon energies. The samples were irradiated with 241Am and 109Cd radioactive point source using transmission arrangement. The gamma- rays were counted by a Si(Li) detector with resolution of 160 eV at 5.9 keV. Total atomic and electronic cross-sections (sigmat and sigmae), effective atomic and electron densities (Zeff and Nel) were determined using the obtained mass attenuation coefficients for investigated Au alloys. The theoretical mass attenuation coefficients of each alloy were estimated using mixture rule.

Gamma-Rays Absorption Studies of PbO-SiO<sub>2</sub> Glass System

Mass attenuation coefficient, total interaction cross-section and effective atomic number of xPbO:(100-x)SiO2, where 30 x 70 (% weight), glass system have been investigated at 662 keV on the basis of the mixture rule. The results are in good agreement with the theoretical values, calculated by WinXCom. The mass attenuation coefficient increases with PbO content, due to higher probability of photoelectric absorption in glass. However, Compton scattering gives dominant contribution to the total mass attenuation coefficient for the glass samples studied. The shielding properties of the glass samples are also better than ordinary shielding concretes and commercial window glasses. These results indicate that the glass systems prepared in this study has a potential to be used as radiation shielding materials.

Mass attenuation coefficients and effective atomic numbers in phosphate glass containing Bi 2O 3, PbO and BaO at 662 keV

In this work, the mass attenuation coefficients, partial interactions and the effective atomic numbers ( Z eff) of Bi 2O 3, PbO and BaO in xR m O n :(100− x)P 2O 5 (where x=30≤ x≤70 (% by weight)) glass system have been investigated on the basis of the mixture rule at 662 keV. The total and partial interactions were calculated by WinXCom software. It has been found that the total mass attenuation coefficients of glasses increase with increasing Bi 2O 3 and PbO concentrations, due to the increasing photoelectric absorption in glass samples. However, Compton scattering gives dominant contribution to the total mass attenuation coefficients for the studied glass samples. The Z eff increases with increase in Bi 2O 3, PbO and BaO concentrations. For comparison, the Z eff of PbO glasses are comparable to that of Bi 2O 3 glasses and Z eff of both glasses are greater than BaO glasses. These results are very useful for designing radiation shielding glass and reflecting the influence of bismuth, barium, and lead content in radiation shielding phosphate glass. Besides the mentioned usefulness of the new materials, development of lead-free radiation protecting glass also leaves non-toxic impact on our environment.