Effective atomic numbers of some vanadium and nickel compounds for total photon interactions using transmission experiments

Effective atomic numbers of V₂O₃,VO₂,VF₃,NH₄VO₃,VF₄,NiF₂,NiCl₂,NiF₂4H₂O,NiCl₂6H₂O,Ni(ClO₄)₂6H₂O were measured in the X-ray energy range 15.746- using an Si(Li) detector. The measured values are compared with the theoretical ones calculated using WinXcom.     

Determination of effective atomic numbers and effective electron densities for Cu/Zn alloy

The mass attenuation coefficients, total interaction cross-sections, effective atomic numbers, effective electron densities and photon mean free paths of the Cu/Zn alloy were determined on the basis of the mixture rule at 356, 511, 662, 835 and 1275 keV gamma-ray energies. The gamma-rays were detected by using an ordinary NaI(Tl) scintillation detection system with a resolution of 10.2% at 662 keV.It was observed that the mixture rule is a suitable method for determination of these parameters. The effective atomic numbers and effective electron densities tend to be almost constant as a function of energy. There is good agreement between experiment and theory, calculated by WinXCom.     

The measurement of total mass attenuation coefficients of CoCuNi alloys

The total mass attenuation coefficients for Co, Cu, Ni elements and CoCu, CoCuNi alloys were measured at different energies with 11.88, 13.93, 17.59, 21.09 and emitted an point source using transmission arrangement. The gamma rays were counted by a Si(Li) detector with a resolution of at . Also the mass attenuation coefficients of each alloy (CoCu, CoCuNi) were estimated using mixture rule. The measured values were compared with estimated values for alloys.     

Photon mass attenuation coefficients,effective atomic numbers and electron densities of some thermoluminescent dosimetric compounds

Photon mass attenuation coefficients of some thermoluminescent dosimetric (TLD) compounds, such as LiF, CaCO₃, CaSO₄, CaSO₄.2H₂O, SrSO₄, CdSO₄, BaSO₄, C₄H₆BaO₄ and 3CdSO₄.8H₂O were determined at 279.2, 320.07, 514.0, 661.6, 1115.5, 1173.2 and 1332.5 keV in a well-collimated narrow beam good geometry set-up using a high resolution, hyper pure germanium detector. The attenuation coefficient data were then used to compute the effective atomic number and the electron density of TLD compounds. The interpolation of total attenuation cross-sections of photons of energyE in elements of atomic numberZ was performed using the logarithmic regression analysis of the data measured by the authors and reported earlier. The best-fit coefficients so obtained in the photon energy range of 279.2 to 320.07 keV, 514.0 to 661.6 keV and 1115.5 to 1332.5 keV by a piece-wise interpolation method were then used to find the effective atomic number and electron density of the compounds. These values are found to be in agreement with other available published values.     

Simulated mixed absorbers and effective atomic numbers for γ attenuation

The total γ-ray interaction cross-sections on mixed absorbers were determined at 662 keV with a view to study the effective atomic numbers for γ-ray absorption under narrow beam good geometry set-up. The measurements were taken for the combination of metallic absorbers like aluminium, copper, lead and mercury and also for the simulated absorbers by rotating the targets. ORTEC HPGe and NaI(Tl) detectors were used for detection of γ-rays. The experimental results compare favourably with theoretical values derived from XCOM package and suggest the usefulness of the concept of effective atomic numbers and the utility of the rotating absorbers technique.     

Effective atomic number and density determination of rocks by X-ray microtomography

Microtomography, as a non-destructive technique, has become an important tool in studies of internal properties of materials. Recently, interest using this methodology in characterizing the samples with respect to their compositions, especially rocks, has grown. Two physical properties, density and effective atomic number, are important in determining the composition of rocks. In this work, six samples of materials with densities that varied from 2.42 to 6.84 g/cm³ and effective atomic numbers from 15.0 to 77.3 were studied. The measurements were made using a SkyScan-Bruker 1172 microtomography apparatus operating in voltages at 50, 60, 70, 80, 90 and 100 kV with a resolution of 13.1 μm. Through micro-CT images, an average gray scale was calculated for the samples and correlation studies of this value with the density and the effective atomic number of samples were made. Linear fits were obtained for each energy value. The obtained functions were tested with samples of Amazonite, Gabbro, Sandstone and Sodalite.     

Radiation Parameters of Some Potential Bioactive Compounds

In this study,we aimed to determine the radiation parameters of some potential bioactive compounds.1-Aryl-3-dibenzylamino-propane-1-on hydrochloride type Mannich bases were synthesized via classical conventional heating method.Aryl part was changed as phenyl(C6H5),4-methylphenyl(4-CH3C6H4),4-fluorophenyl(4-FC6H4),4-nitrophenyl(4-NO2C6H4),4-chlorophenyl(4-ClC6H4),4-bromophenyl(4-BrC6H4),and 2-thienyl(C4H3S-2-yl).Mass attenuation coefficient(μm),effective atomic number(Zeff)and effective electron density(Nel)of compounds were determined experimentally and theoretically for at 8.040,8.910,13.40,14.96,17.48,19.61,22.16,24.94,32.19,36.38,44.48,50.38and 59.54keV photon energies by using an HPGe detector with a resolution of 182eV at 5.9keV.Radiation parameters of these compounds which can be anti-cancer drug candidate were given in the tables.The results show that phenyl ring behave like thiophene ring in terms of radiation absorption.It is thought that the results of study may drive allow the development of drug candidate new compounds in medical oncology.     

Simulation study for atomic size and alloying effects during forming processes of amorphous alloys

1 Introduction Since amorphous alloys were successfully prepared by Duwez et al.[1] in the 1960s by rapid cooling from the eutectic alloy of Ag-Cu system, the investigation about atomic size and alloying effects during the formation process of amorphous alloys has become such an important area that many people paid a good deal attention. From the experiments that AgxCu1-x alloys formed amorphous structures, Takayama[2] has determined the content range of amorphous alloys, being x = 35—65, …     

Mass attenuation coefficients for n-type InSe, InSe:Gd, InSe:Ho and InSe:Er single crystals

Measurements have been made to determine the mass attenuation coefficients of undoped n-type InSe, and Gd, Ho, Er doped n-InSe single crystals using a Si(Li) detector in the energy region 15.746–40.930 keV X-ray energies with energy dispersive X-ray fluorescence systems. InSe, InSe:Gd, InSe:Ho and InSe:Er single crystals were grown by using the stockbarger method. The measured values are graphically compared with the theoretical ones obtained using WinXcom.     

Measurement of mass attenuation coefficients for holmium doped and undoped layered semiconductors InSe at different energies and the validity of mixture rule for crystals around the absorption edge

The mass attenuation coefficients of InSe and InSe having different holmium concentrations were measured in the energy region 15.746-40.930 keV using a Si(Li) detector. InSe and InSe:holmium(0.0025), InSe:holmium(0.0050), InSe:holmium(0.025) and InSe:holmium(0.05) crystals were grown by the Bridgman-Stocbarger method. The measured values are compared with the theoretical ones obtained using WinXcom which is a Windows version of XCOM. The measurement of mass attenuation coefficients of ternary semiconductors is very important because of its use in technology.     

On the evaluation of Bernoulli numbers using binomial coefficients

A new algorithm is presented for calculating the Bernoulli numbers valid for all values of their argument. We introduce a simple, new analytical computer method for calculating the Bernoulli numbers on the basis of their integral expressions. The formula given in this study for the evaluation of Bernoulli numbers shows good rate of convergence and numerical stability with existing formulas.     

A simple post-accelerator foil stripper assembly for atomic collision experiments

A multiple foil holder for use in ultra high vacuum (UHV) environment as a post accelerator ion stripper has been designed and fabricated. It is used to produce beams of an ion in different charge states at a given energy from a 14 MV pelletron accelerator. These ions are required in several types of atomic collision experiments. The assembly is tested with³²S ions at various energies.     

Effective attenuation length dependence on photoelectron kinetic energy for Au from 1 keV to 15 keV

Hard X-ray PhotoElectron Spectroscopy (HAXPES) is an extremely powerful tool for the electronic, compositional, and chemical characterization of bulk materials and buried interfaces. Its success is based on the dramatic increase of the electron effective attenuation length (EAL) with increasing photoelectron kinetic energy. EALs are well established for electrons with kinetic energies up to several keV (below 3 keV). However, few data are available for kinetic energies up to 15 keV. In the present study we have determined the EAL dependency on kinetic energy for gold from 1 keV up to 15 keV. Two different approaches have been used. The first approach consists of following the signal rate from a core level for a fixed kinetic energy as a function of overlayer thickness (overlayer method). The second approach consists of following the signal rate from a core level as a function of the incident photon energy, i.e., electron kinetic energy, for a fixed overlayer thickness (depth profile method). An EAL dependency of EAL (nm) = 0.022 × E_kin (eV)^0.627 has been obtained from both methods. Hence, the EAL, for gold, is 4.7, 7.3 and 9.4 nm for 5 keV, 10 keV and 15 keV electron kinetic energies, respectively. A comparison between the experimental data and the EALs predicted by practical expressions available in the literature is also performed.     

中低温等离子体原子能量的分波法计算

在改进的平均原子模型的基础上，在中心场近似下用分波法处理自由电子密度分布函数，提高了电子波函数、电子占据数等原子参数的计算精度.通过使用分波法准确计算电子间各部分的相互作用能，使得原子能量的计算结果更加准确，零温基态能的计算结果与Hartree-Fock理论给出的结果很好地符合.作为算例，计算了W，Au，Rn，Am等元素的原子能量、熵及定容热容. 关键词： 自洽场原子结构 原子能量     

Relations between compositional modulation and atomic ordering degree in thin films of ternary III—V semiconductor alloys

This paper derives the expressions for the ordering degree and the modulation factor of A and B atoms in A_xB_1-xC epilayers of ternary III--V semiconductor alloys. Using these expressions, it identifies quantitatively the alternating atom-enhanced planes, compositional modulations, atomic ordering degree on the group-III sublattices and the fine structure of NMR spectra.     

以最大原子密度定义合金相中的第一近邻团簇

本文提出利用不同壳层所包含的径向原子密度, 即单位体积内的原子个数随着径向的分布, 来方便而精确地定义团簇, 即具有最大径向原子密度的且表面呈现三角密堆结构的完整壳层为第一近邻团簇. 最后以Al-Ni-Zr合金相为例说明了该方法的合理性与适用性, 及此方法所定义的团簇与非晶形成的关系.     

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.     

利用不同原子模型计算局部热力学平衡等离子体电离态(英文)

等离子体电离态分布是等离子体物理学中被广泛应用的重要物理量之一,而原子数据是电离态计算的前提.首先,利用Rubiano相对论性原子结构模型、Faussurier非相对论原子结构模型和高度简化的More模型,分别计算各种电离度的Fe离子能量.通过与自洽场结果的比较后认为,Faussurier模型给出的原子数据比较精确可靠.然后,再利用以上模型研究了局部热力学平衡Fe等离子体电离态随温度和密度的变化情况.计算结果表明,不同原子模型提供的原子数据对平均电离度的计算结果影响不大,但明显地影响等离子体中的离子丰度.本文对这些差异进行了物理分析.     

An in situ atomic force microscope for normal‐incidence nanofocus X‐ray experiments

A compact high‐speed X‐ray atomic force microscope has been developed for in situ use in normal‐incidence X‐ray experiments on synchrotron beamlines, allowing for simultaneous characterization of samples in direct space with nanometric lateral resolution while employing nanofocused X‐ray beams. In the present work the instrument is used to observe radiation damage effects produced by an intense X‐ray nanobeam on a semiconducting organic thin film. The formation of micrometric holes induced by the beam occurring on a timescale of seconds is characterized.     

强流辐照钛合金表面特征的原子力显微研究

利用原子力显微术的轻敲模式(TM-AFM),并采用形貌与相位同时成像技术对强流脉冲离子束(IPIB)辐照前后试样表面进行了系统标征,得到了试样表面的高度像及相位像的衬度.分析结果表明:在高流强密度、多次脉冲条件下,IPIB辐照可使试样表面变得光滑化,从相位像中可以定性分析出辐照后表面硬度也得到一定程度的提高.