Study of radiation interaction parameters for organic compounds at gamma photon energies different from available standard radioisotopes

The present work emphasizes on the transmission of gamma photons, having energies in the range (241.8–401.8 keV) obtained by Compton scattering technique, to determine mass-attenuation coefficients (μ_m), molar-extinction coefficients (ε), mass-energy absorption coefficient (μ_en/ρ), effective atomic number (Z_eff), mean free path (MFP), half value layer (HVL), total atomic (σ_t.a) and electronic (σ_t.el) cross-sections, and Hounsfield number (H) of various organic compounds like Alcohols, Aldehydes, Ketones, Esters, Amines, Benzene compounds and Water, and further used as radiation shielding. The WinXcom software package is used to compare the experimentally deduced radiation interaction parameters with theory. The theoretical and experimental results are in good agreement within permissible experimental uncertainty. The radiation shielding parameters have been found to vary with gamma-ray energy and effective atomic number for these organic compounds under present investigations.     

Measurement of attenuation cross-sections of some fatty acids in the energy range 122–1330 keV

The mass attenuation coefficients (μ_m) have been measured for undecylic acid (C₁₁H₂₂O₂), lauric acid (C₁₂H₂₄O₂), tridecylic acid (C₁₃H₂₆O₂), myristic acid (C₁₄H₂₈O₂), pentadecylic acid (C₁₅H₃₀O₂) and palmitic acid (C₁₆H₃₂O₂) using ⁵⁷Co, ¹³³Ba, ¹³⁷Cs, ⁶⁰Co and ²²Na emitted γ radiation with energies 122, 356, 511, 662, 1170, 1275 and 1330 keV, respectively. The accurate values of the effective atomic number (Z_eff), atomic cross-section (σ_t,), electronic cross-section (σ_e) and the effective electron density (N_eff) have great significance in radiation protection and dosimetry. These quantities were obtained by utilizing experimentally measured values of mass attenuation coefficients (μ_m). A NaI(Tl) scintillation detector with 8.2% (at 662 keV) resolution was used for detecting of attenuated γ-photons. The variation in Z_eff and N_eff of fatty acids with energy is discussed. The experimental and theoretical results are in good agreement within 2% deviation.     

Gamma ray shielding capabilities of rhenium-based superalloys

ABSTRACT

Because of the high radiation dose in applications involving nuclear reactors, medical treatments etc., it is important to reduce the exposure to radiation of areas and workers. In this study, we were examined gamma ray shielding parameters of the newly produced Re-based superalloys. Mass attenuation coefficient (µ/ρ) of the alloys were obtained experimentally at 81, 276, 302, 356, 383 keV photon energies emitted from ¹³³Ba radioactive source using Ultra Ge detector. The experimental results were compared with the values obtained by the WinXCOM program and were found to be in perfect agreement with each other. Additionally, effective atomic number (Z_eff) and electron density (N_eff) were determined for produced Rhenium (Re) based super alloys in the energy range 1 keV–100?GeV. S5 sample which has maximum Rhenium percentage own the largest µ/ρ and Z_eff values. Moreover, by using Geometric Progression (GP) approximation, EABF and EBF were computed for the superalloys depending on the energy and penetration depths. It has been deduced that the values of EABF and EBF are minimum in the medium energy region. EBF and EABF values of the alloys have changed depending on the equivalent atomic number. Among alloy samples under study, S5 superalloy is the best for gamma ray shielding. However, in general, considering the radiation energies used in many applications, all the alloys under study have satisfactory radiation absorption properties.     

White and some colored marbles as alternative radiation shielding materials for applications

ABSTRACT

In this paper, the radiation shielding parameters such as linear attenuation coefficients (LAC, µ), mass attenuation coefficients (MAC, µ/ρ), effective atomic numbers (Z_eff), effective electron densities (N_eff), half value of layers (HVL), mean free paths (MFP) and buildup factors (exposure (EBF) and energy absorption (EABF)) were investigated for cream (M1), pink (M2), white (M3), maroon (M4) and green (M5) marbles. Attenuation coefficients were measured in the energy region 31.18–661.66 keV photon energies. The values of Z_eff and N_eff were then calculated using these coefficients with logarithmic interpolation method, and HVLs and MFPs were calculated using the values of LAC of marble samples at the same photon energies. The experimental results were compared with the theoretical values obtained from WinXCom program, and good agreements were observed between the experimental and theoretical results. HVLs and MFPs of all marble samples were compared with those of some concretes, glasses and commercial radiation shielding glasses (SCHOTT Co.). The studied marbles were better radiation shielding materials than standard shielding concretes due to lower HVL and MFP values lower than the ordinary concrete. Finally, EBFs and EABFs of the marbles were calculated in the energy region 0.015–1?MeV up to penetration depths of 40 mfps by Geometric Progression method (G-P), and the results were discussed in terms of photon energies and chemical compositions of the marbles.     

Measurement of atomic number and mass attenuation coefficient in magnesium ferrite

Pure magnesium ferrite sample was prepared by standard ceramic technique and characterized by X-ray diffraction method. XRD pattern revealed that the sample possess single-phase cubic spinel structure. The linear attenuation coefficient (μ), mass attenuation coefficient (μ/ρ), total atomic cross-section (σ _tot), total electronic cross-section (σ _ele) and the effective atomic number (Z _eff) were calculated for pure magnesium ferrite (MgFe₂O₄). The values of γ-ray mass attenuation coefficient were obtained using a NaI energy selective scintillation counter with radioactive γ-ray sources having energy 0.36, 0.511, 0.662, 1.17 and 1.28 MeV. The experimentally obtained values of μ/ρ and Z _eff agreed fairly well with those obtained theoretically.      

Gamma or X-rays attenuation properties of some biochemical compounds

The probability of gamma or X-ray interactions with important 14 antioxidants have been discussed for total photon interactions in the wide energy range of 1?keV–100?GeV using the WinXCOM code. The variations of mass attenuation coefficient (μ_ρ), effective atomic number (Z_eff) and electron density (N_el) with photon energy were plotted for total photon interactions. It was found that the values of μ_ρ, Z_eff and N_el depend on the incoming photon energy and chemical compositions of antioxidant. The highest values of these parameters were found at a low-energy zone where the photoelectric effect is the dominant interaction process. When antioxidants were compared with each other, it was seen that Z_eff has the highest values for Oenin chloride and Delphinidin chloride which contain the Cl element. This investigation is thought to be useful for medical applications where radiation exposure is present.     

Unique dielectric properties in polyaniline/poly(vinylidene fluoride) composites induced by temperature variation

To explore an effect of temperature on the dielectric properties in polyaniline/poly(vinylidene fluoride) (PANI/PVDF) composites, the dielectric properties of these composites with different volumetric fractions of PANI (?_PANI) were studied in a wide temperature range. An increase in the effective conductivity (σ_eff) and dielectric permittivity (?_eff) was observed with increasing temperature in all PANI/PVDF composites. Particularly, for the composite with ?_PANI = 0.01, less than the percolation threshold (?_C = 0.045), the increase in σ_eff and ?_eff was most significant. A tunneling effect could be responsible for the unique dielectric properties. The results provided us useful information related to the microstructure of composites, which was not reported previously. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Molar extinction coefficients of some carbohydrates in aqueous solutions

Molar extinction coefficients of some carbohydrates viz. l-arabinose (C₅H₁₀O₅), d-glucose (C₆H₁₂O₆), d-mannose (C₆H₁₂O₆), d-galactose (C₆H₁₂O₆), d(-) fructose (C₆H₁₂O₆) and maltose (C₁₂H₂₄O₁₂) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying within experimental uncertainty. Within concentration ranges studied, Beer-Lambert law is obeyed very well.     

Variation of gamma radiation shielding properties with incident photon energy and penetration depth for WC/Al composites

In this work, we examined the usefulness of the WC_x/Al_100?x composites (x?=?10, 20, 50, 80 wt. %) for gamma-ray shielding materials. The mass attenuation coefficient (μ/ρ), effective atomic number (Z_eff), electron density (N_e) and energy absorption buildup factor (EABF) and exposure buildup factor (EBF) for WC_x/Al_100?x composites have been calculated by theoretical approach using XCOM program within the energy range 1?keV–100?GeV, 10 keV–1?GeV, 10 keV–1?GeV and 0.015?MeV–15?MeV, respectively. The results showed that both the values of mass attenuation coefficient and Z_eff of the WC_x/Al_100?x composites tend to increase with the increase of the WC concentration. For the energy region below 3?MeV, the WC₈₀/Al₂₀ composite was found to possess superior gamma-ray shielding effectiveness due to its higher values of both mass attenuation coefficient and effective atomic number, and lower values of both EABF and EBF values. However, for the energy region above 3?MeV, the EBF and EABF values of the WC/Al composites are directly proportional to their Z_eff values, leading to the lowest EBF and EABF values of the WC₁₀/Al₉₀ composites.     

Nuclear radiation shielding and mechanical properties of colemanite mineral doped concretes

ABSTRACT

The present research focused on the investigation of photon and fast neutron shielding parameters of colemanite mineral doped and undoped concretes. The fabricated concretes have been exposed to gamma rays at 59.5 and 81?keV energies and the measurements have been carried out with NaI(Tl) detector. The parameters of effective atomic number (Z_eff) and electron density (N_el) have been determined experimentally and theoretically. The exposure buildup factor (EBF) and energy absorption buildup factor (EBF) have been computed utilizing the Geometric progression (G–P) fitting method. In addition to the photon shielding parameters, the macroscopic effective removal cross-section calculations for fast neutron (Σ_R) were performed. As a result, it was observed that the concretes doped with colemanite mineral are not very effective in gamma radiation shielding. On the contrary, it was observed that concretes with colemanite were more effective in shielding fast neutrons and the fast neutron removal cross-section values increased with increasing colemanite concentration in the concrete. Additionally, compressive strength values (MPa) of concretes were tested using ALFA TESTING (B001-PC) 200 tons capacity device.     

Determination of effective atomic numbers and mass attenuation coefficients of samples using in‐situ energy‐dispersive X‐ray fluorescence analysis

The matrix effect has a major impact on energy‐dispersive X‐ray fluorescence analysis (EDXRFA) and is difficult to be evaluated due to that the contents of some low‐atomic‐number elements cannot be identified by in‐situ EDXRFA. Up to today, the fundamental parameter algorithm proposed by Rousseau has been widely applied to correct the matrix effect. Accordingly, determining the matrix and mass attenuation coefficient (μ/ρ) of sample is a key issue for the fundamental parameter algorithm. In present work, the method to deduce μ/ρ by effective atomic number (Z_eff) was studied. First, the relationship between Z_eff and coherence to Compton scatting ratio (R) of the incident X‐ray was determined by standard samples. Then, we deduce Z_eff and their μ/ρ. The value of μ/ρ deduced by our method is in good agreement with that calculated by WinXCOM, and the relative change (Δ) is less than 7%. We also deduced Z_eff and their μ/ρ of Chinese national standard soil samples employing our method and good agreement with the calculated values were also obtained. We found that the agreement between experimental values of μ/ρ with theoretical values by WinXCOM still exists when the energy of the incident X‐ray is greater than 4 keV, and the Δ is less than 10%. The result indicates that our method may be applied directly to in‐situ EDXRFA.     

Experimental evaluation of effective atomic number of composite materials using back-scattering of gamma photons

A method has been presented for calculation of effective atomic number (Z_eff) of composite materials, by using back-scattering of 662?keV gamma photons obtained from a ¹³⁷Cs mono-energetic radioactive source. The present technique is a non-destructive approach, and is employed to evaluate Z_eff of different composite materials, by interacting gamma photons with semi-infinite material in a back-scattering geometry, using a 3^″?×?3^″ NaI(Tl) scintillation detector. The present work is undertaken to study the effect of target thickness on intensity distribution of gamma photons which are multiply back-scattered from targets (pure elements) and composites (mixtures of different elements). The intensity of multiply back-scattered events increases with increasing target thickness and finally saturates. The saturation thickness for multiply back-scattered events is used to assign a number (Z_eff) for multi-element materials. Response function of the 3^″?×?3^″ NaI(Tl) scintillation detector is applied on observed pulse-height distribution to include the contribution of partially absorbed photons. The reduced value of signal-to-noise ratio interprets the increase in multiply back-scattered data of a response corrected spectrum. Data obtained from Monte Carlo simulations and literature also support the present experimental results.     

A comparative study of gamma-ray interaction and absorption in some building materials using Zeff-toolkit

The gamma-ray shielding behaviour of a material can be investigated by determining its various interaction and energy-absorption parameters (such as mass attenuation coefficients, mass energy absorption coefficients, and corresponding effective atomic numbers and electron densities). Literature review indicates that the effective atomic number (Z_eff) has been used as extensive parameters for evaluating the effects and defect in the chosen materials caused by ionising radiations (X-rays and gamma-rays). A computer program (Z_eff-toolkit) has been designed for obtaining the mean value of effective atomic number calculated by three different methods. A good agreement between the results obtained with Z_eff-toolkit, Auto_Z_eff software and experimentally measured values of Z_eff has been observed. Although the Z_eff-toolkit is capable of computing effective atomic numbers for both photon interaction (Z_eff,PI) and energy absorption (Z_eff,En) using three methods in each. No similar computer program is available in the literature which simultaneously computes these parameters simultaneously. The computed parameters have been compared and correlated in the wide energy range (0.001–20?MeV) for 10 commonly used building materials. The prominent variations in these parameters with gamma-ray photon energy have been observed due to the dominance of various absorption and scattering phenomena. The mean values of two effective atomic numbers (Z_eff,PI and Z_eff,En) are equivalent at energies below 0.002?MeV and above 0.3?MeV, indicating the dominance of gamma-ray absorption (photoelectric and pair production) over scattering (Compton) at these energies. Conversely in the energy range 0.002–0.3?MeV, the Compton scattering of gamma-rays dominates the absorption. From the 10 chosen samples of building materials, 2 soils showed better shielding behaviour than did other 8 materials.     

Experimental measurement of effective atomic number of composite materials for Compton effect in the <Emphasis Type="Italic">γ</Emphasis>-ray region 280–1115 keV by a new method

In this paper, we report a new method to determine the effective atomic number, Z _eff, of composite materials for Compton effect in the γ-ray region 280–1115 keV based on the theoretically obtained Klein–Nishina scattering cross-sections in the angular range 50°–100° as well as a method to experimentally measure differential incoherent (Compton) scattering cross-sections in this angular range. The method was employed to evaluate Z _eff for different inorganic compounds containing elements in the range Z = 1–56, at three scattering angles 60°, 80° and 100° at three incident gamma energies 279.1 keV, 661.6 keV and 1115.5 keV and we have verified this method to be an appropriate method. Interestingly, the Z _eff values so obtained for the inorganic compounds were found to be equal to the total number of electrons present in the sample as given by the atomic number of the elements constituting the sample in accordance with the chemical formula of the sample. This was the case at all the three energies.     

Investigation of radiological properties of some shielding materials on charged and uncharged radiation interaction for neutron generator

Radiation interaction parameters such as total stopping power, projected range (longitudinal and lateral) straggling, mass attenuation coefficient, effective atomic number (Z_eff) and electron density (N_eff) of some shielding materials were investigated for photon and heavy charged particle interactions. The ranges, stragglings and mass attenuation coefficients were calculated for the high-density polyethylene(HDPE), borated polyethylene (BPE), brick (common silica), concrete (regular), wood, water, stainless steel (304), aluminum (alloy 6061-O), lead and bismuth using SRIM Monte Carlo software and WinXCom program. In addition, effective atomic numbers (Z_eff) and electron densities (N_eff) of HDPE, BPE, brick (common silica), concrete (regular), wood, water, stainless steel (304) and aluminum (alloy 6061-O) were calculated in the energy region 10?keV–100?MeV using mass stopping powers and mass attenuation coefficients. Two different methods namely direct and interpolation procedures were used to calculate Z_eff for comparison and significant differences were determined between the methods. Variations of the ranges, longitudinal and lateral stragglings of water, concrete and stainless steel (304) were compared with each other in the continuous kinetic energy region and discussed with respect to their Z_effs. Moreover, energy absorption buildup factors (EABF) and exposure buildup factors (EBF) of the materials were determined for gamma rays as well and were compared with each other for different photon energies and different mfps in the photon energy region 0.015–15?MeV.     

Stereodynamics of the reactions Ne+H2+/Ne+D2+/Ne+T2

The vector correlations between products and reagents for the reactions Ne+H + 2 , Ne+D + 2 , and Ne+T + 2 are calculated by means of the quasi-classical trajectory method on a new potential energy surface constructed by Lü et al. [J. Chem. Phys. 2010 132, 014303]. The polarization-dependent differential cross-sections (2π/σ)(dσ 00 /dω t ), (2π/σ)(dσ 20 /dω t ), (2π/σ)(dσ 22+ /dω t ), and (2π/σ)(dσ 21 /dω t ), and the distributions of P (θ r ), P (φ r ), and P (θ r ,φ r ) are calculated. The isotopic effect, which is associated with the difference in mass factor among the three reactions, is revealed.     

Prediction of ortho substituent effect in alkaline hydrolysis of substituted phenyl benzoates in aqueous acetonitrile

The second‐order rate constants k (dm³mol^?1s^?1) for alkaline hydrolysis of meta‐, para‐ and ortho‐substituted phenyl esters of benzoic acid, C₆H₅CO₂C₆H₄‐X, in aqueous 50.9% (v/v) acetonitrile have been measured spectrophotometrically at 25 °C. In substituted phenyl benzoates, C₆H₅CO₂C₆H₄‐X, the substituent effects log k_X ? log k_H in aqueous 50.9% acetonitrile at 25 °C for para, meta and ortho derivatives showed good correlations with the Taft and Charton equations, respectively. Using the log k values for various media at 25 °C, the variation of the ortho substituent effect with solvent was found to be precisely described with the following equation: Δlog k_ortho = log k_ortho ? log k_H = 1.57σ_I + 0.93σ°_R + 1.08E_s^B ? 0.030ΔEσ_I ? 0.069ΔEσ°_R, where ΔE is the solvent electrophilicity, ΔE = E_S ? E_H20, characterizing the hydrogen‐bond donating power of the solvent. We found that the experimental log k values for ortho‐, para‐ and meta‐substituted phenyl benzoates in aqueous 50.9% acetonitrile at 25 °C, determined in the present work, precisely coincided with the log k values predicted with the equation (log k^X)_calc = (log k^H_AN)_exp + (Δlog k^X)_calc where the substituent effect (Δlog k^X)_calc was calculated from equation describing the variation of the substituent effect with the solvent electrophilicity parameter, using for aqueous 50.9% CH₃CN the solvent electrophilicity parameter, ΔE = ?5.84. In going from water to aqueous 50.9% CH₃CN, the ortho inductive term grows twice less as compared with the para polar effect. Copyright © 2013 John Wiley & Sons, Ltd.     

Mössbauer study on the orientations of the hyperfine interactions at57Fe in [Fe(H2O)6](NH4)2(SO4)2 exposing absorber and57Co:Rh source to high magnetic fields

Single crystal Mössbauer spectra of the paramagnetic salt [Fe(H₂O)₆)(NH₄)₂(SO₄)₂ at 4.2 K and in fields up to 5 T yield unique results on the EFG and the effective fieldH _eff at the nucleus if one uses polarized -rays. Especially the direction of the effective field is determined uniquely. The ordinary⁵⁷Co:Rh source is polarized at room temperature in the stray field of that magnet, which produces the field at the position of the absorber. Polarization and thickness of the absorber are taken into account.