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Sample records for absorber-materials atomic numbers

  1. Calculations of effective atomic number

    Kaliman, Z. [Department of Physics, Faculty of Arts and Sciences, Omladinska 14, Rijeka (Croatia); Orlic, N. [Department of Physics, Faculty of Arts and Sciences, Omladinska 14, Rijeka (Croatia)], E-mail: norlic@ffri.hr; Jelovica, I. [Department of Physics, Faculty of Arts and Sciences, Omladinska 14, Rijeka (Croatia)

    2007-09-21

    We present and discuss effective atomic number (Z{sub eff}) obtained by different methods of calculations. There is no unique relation between the computed values. This observation led us to the conclusion that any Z{sub eff} is valid only for given process. We illustrate calculations for different subshells of atom Z=72 and for M3 subshell of several other atoms.

  2. Diffusion coefficients for absorbing materials

    A method to improve the diffusion results for systems containing strong absorbers is described. Each absorbing material is transformed into an equivalent rectangle. Transport and diffusion calculations in slab geometry are performed for both directions of the rectangle, and group-dependent diffusion coefficients are determined by matching the outgoing currents. Test problems comprise a critical slab, a compact PWR fuel element storage pool and two BWR fuel elements with a control rod and a poison cell. The multiplication factors of these systems are calculated with an accuracy of 1 to 2%. (Auth.)

  3. Effect of the Number of Benzene-Ring, the Functional Groups and the Absorbent Material on the Performance of Pt Nanoparticles Supported on Modified Graphite Nanoplatelet

    A graphite nanoplatelet (GNP) modified with small organic molecules and inorganic element was prepared and subsequently used as an electrocatalyst for the electrooxidation of methanol. The Pt/modified-GNP composite catalyst was characterized by Raman spectrometer, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties and electrocatalytic activities of the Pt/modified-GNP hybrid were evaluated by cyclic voltammetry and chronoamperometry. The results indicate that the number of benzene-ring in the organic molecules and the identity of the inorganic elements can influence the dispersion of the Pt nanoparticles. Combine the inorganic elements with aminopyrene (amin) improved the activity of the resultant catalysts for methanol electrooxidation. The activity of the catalysts exhibits an order of Pt/Sn-amin-G < Pt/Ce-amin-G < Pt/Al-amin-G

  4. Absorber materials in CANDU PHWRs

    In a CANDU reactor the fuel channels are arranged on a square lattice in a calandria filled with heavy water moderator. This arrangement allows five types of tubular neutron absorber devices to be located in the relatively benign environment of low pressure, low temperature heavy water between neighbouring rows or columns of fuel channels. This paper will describe the roles of the devices and outline the design requirements of the absorber component from a reactor physics viewpoint. Nuclear heating and activation problems associated with the different absorbers will be briefly discussed. The design and manufacture of the devices will be also discussed. The control rod absorbers and shut off materials are cadmium and stainless steel. In the tubular arrangement, the cadmium is sandwiched between stainless steel tubes. This type of device has functioned well, but there is now concern over the availability and expense of cadmium which is used in two types of CANDU control devices. There are also concerns about the toxicity of cadmium during the fabrication of the absorbers. These concerns are prompting AECL to study alternatives. To minimize design changes, pure boron-10 alloyed in stainless steel is a favoured option. Work is underway to confirm the suitability of the boron-loaded steel and identify other encapsulated absorber materials for practical application. Because the reactivity devices or their guide tubes span the calandria vessel, the long slender components must be sufficiently rigid to resist operational vibration and also be seismically stable. Some of these components are made of Zircaloy to minimize neutron absorption. Slow irradiation growth and creep can reduce the spring tension, and periodic adjustments to the springs are required. Experience with the control absorber devices has generally been good. In one instance liquid zone controllers had a problem of vibration induced fretting but a redesigned back-fit resolved the problem. (author). 3 refs, 8

  5. Space Compatible Radar Absorbing Materials Project

    National Aeronautics and Space Administration — This SBIR Phase 1 project shall investigate novel radar absorbing materials (RAM) for use in space or simulated space environments. These materials are lightweight...

  6. Technology and assessment of neutron absorbing materials

    The present review assesses more recent developments in the technology and application of those absorber materials which are considered to be established or to have shown potential in reactor control. Emphasis is placed on physical, chemical and metallurgical properties and upon irradiation behaviour. (author)

  7. Absorber Materials at Room and Cryogenic Temperatures

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  8. Moisture buffering capacity of highly absorbing materials

    Cerolini, S.; D' Orazio, M.; Stazi, A. [Department of Architecture, Construction and Structures (DACS), Faculty of Engineering, Polytechnic University of Marche, Via Brecce Bianche, 60100 Ancona (Italy); Di Perna, C. [Department of Energetics, Faculty of Engineering, Polytechnic University of Marche, Via Brecce Bianche, 60100 Ancona (Italy)

    2009-02-15

    This research investigates the possibility to use highly absorbing materials to dampen indoor RH% variations. The practical MBV of sodium polyacrylate, cellulose-based material, perlite and gypsum is evaluated for a daily cyclic exposure that alternates high (75%) and low (33%) RH% levels for 8 h and 16 h, respectively. The adjustment velocity to RH% variations and the presence of hysteretic phenomena are also presented. The cellulose-based material proves to be the most suitable for moisture buffering applications. Starting from this material's properties, the effect of thickness, vapour resistance factor ({mu}) and mass surface exchange coefficient (Z{sub v}) on sorption capacity is evaluated by the use of a numerical model. (author)

  9. Effective atomic number of dental smalt

    The effective atomic numbers Z are enough utilized for to characterize the interactions of ionizing radiation with matter. Particularly for the Z calculation in biological tissues and/or composed materials we need to know the relationship between the cross sections of the diverse radiations interactions with mattera and the atomic numbers Z of the constituent elements in the tissue or composed material. Normally the cross section by atom σ 2 is proportional to Zm. The m value depends of the iterative process type and the energy of the incident photons. In the case of the photoelectric interaction, the m vary will vary between 4,698 and 4,799 for energies between 10 to 200 keV. It was verified that constituent elements with high Z (>20) they had a major contribution. The m values for the Compton interation and the coherent scattering were calculated of similar way. Knowing the m values, we calculate the partials Z of a composed material. For the calculation of total Z, we can use alternatives starting from the equivalent atomic number corresponding to the total cross section σ d tot, mc of the composed material. In this work for the calculation of Z values corresponding to diverse interations, we applied a linear regression at the values of Ln σ a x LnZ for different energies. In general, to characterize a simulator material of a tissue or composed material we need to know the total Z in function of the photon energy applied to dental smalt increases until some hundreds of keV the partial values of Z owing to photoelectric effect and the coherent scattering this is owing to the smalt has a great concentration of elements with high Z. (Author)

  10. Porphyrin Based Near Infrared-Absorbing Materials for Organic Photovoltaics

    Zhong, Qiwen

    photosynthesis. Photosynthesis uses light from the sun to drive a series of chemical reactions. Most natural photosynthetic systems utilize chlorophylls to absorb light energy and carry out photochemical charge separation that stores energy in the form of chemical bonds. The sun produces a broad spectrum of light output that ranges from gamma rays to radio waves. The entire visible range of light (400-700 nm) and some wavelengths in the NIR (700-1000 nm), are highly active in driving photosynthesis. Although the most familiar chlorophyll-containing organisms, such as plants, algae and cyanobacteria, cannot use light longer than 700 nm, anoxygenic bacterium containing bacteriochlorophylls can use the NIR part of the solar spectrum. No organism is known to utilize light of wavelength longer than about 1000 nm for photosynthesis. NIR light has a very low-energy content in each photon, so that large numbers of these low-energy photons would have to be used to drive the chemical reactions of photosynthesis. This is thermodynamically possible but would require a fundamentally different molecular mechanism that is more akin to a heat engine than to photochemistry. Early work on developing light absorbing materials for OPVs was inspired by photosynthesis in which light is absorbed by chlorophyll. Structurally related to chlorophyll is the porphyrin family, which has accordingly drawn much interest as the potential light absorbing component in OPV applications. In this dissertation, the design and detail studies of several porphyrin-based NIR absorbing materials, including pi--extended perylenyl porphryins and pyrazole-containing carbaporphyrins, as well as porphyrin modified single-walled carbon nanotube hybrids, will be presented, dedicating efforts to develop novel and application-oriented materials for efficient utilization of sustainable solar energy.

  11. Development of highly effective neutron shields and neutron absorbing materials

    A wide range of materials, including polymers and hydrogen-occluded alloys that might be usable as the neutron shielding material were examined. And a wide range of materials, including aluminum alloys that might be usable as the neutron-absorbing material were examined. After screening, the candidate material was determined on the basis of evaluation regarding its adaptabilities as a high-performance neutron-shielding and neutron-absorbing material. This candidate material was manufactured for trial, after which material properties tests, neutron-shielding tests and neutron-absorbing tests were carried out on it. The specifications of this material were thus determined. This research has resulted in materials of good performance; a neutron-shielding material based on ethylene propylene rubber and titanium hydride, and a neutron-absorbing material based on aluminum and titanium hydride. (author)

  12. Preparation of A New Type of Stress-absorbed Material

    WU Shao-peng; YANG Tao; YUAN Hai-qing

    2004-01-01

    Neoprene latex modified emulsified bitumen and fine aggregate are used to prepare a new type of stress-absorbed material, which has strong ability of anti-reflective cracking on asphalt concrete over layer-constructed upon a semi-rigid type base course or cement concrete pavement block. Experimental results demonstrate the stress-absorbed material have excellent mechanical properties including a low modulus of elasticity, high ultimate tensile stress and strain, and a strong distortion ability. Stress concentration in asphalt over layer originated by temperature changes and traffic loads can be alleviated.

  13. Absorbent material for type a radioactive materials packaging containing liquids

    The application of absorbent materials to the packaging and transport of liquid radioactive materials in Type A packages has not been reported in the literature. However, a significant body of research exists on absorbent materials for personal hygiene products such as diapers. Absorption capacity is dependent on both the absorbent material and the liquid being absorbed. Theoretical principles for capillary absorption in both the horizontal and the vertical plane indicate that small contact angle between the absorbent fibre and the liquid, and a small inter-fibre pore size are important. Some fluid parameters such as viscosity affect the rate of absorption but not the final absorption capacity. There appears to be little comparability between results obtained for the same absorbent and fluid using different test procedures. Test samples of materials from several classes of potential absorbents have been evaluated in this study, and shown to have a wide range of absorbent capacities. Foams, natural fibres, artificial fibres and granular materials are all potentially useful absorbents, with capacities ranging from as little as 0.86 to as much as 40.6 grams of distilled water per gram of absorbent. Two experimental procedures for evaluating the absorbent capacity of these materials have been detailed in this report, and found suitable for evaluating granular, fibrous or foam materials. Compression of the absorbent material reduces its capacity, but parameters such as relative humidity, pH, temperature, and viscosity appear to have little significant influence on capacity. When the materials were loaded to 50% of their one-minute absorbency, subsequent loss of the absorbed liquid was generally minimal. All of the absorbent materials rapidly lost their absorbed water through evaporation within twenty-four hours in still air at 21 degrees C and 50% relative humidity

  14. Analysis of the atom-number correlation function in a few-atom trap

    Choi, Youngwoon; Yoon, Seokchan; Kang, Sungsam; Kim, Woongnae; Lee, Jai-Hyung; An, Kyungwon

    2006-01-01

    Stochastic properties of loading and loss mechanism in a few atom trap are analyzed. An approximate formula is derived for the atom-number correlation function for the trapped atoms in the limit of reasonably small two-atom loss rate. Validity of the approximate formula is confirmed by numerical simulations.

  15. ABSORBENT MATERIALS BASED ON KRAFT PULP: PREPARATION AND MATERIAL CHARACTERIZATION

    Fredrik Wernersson Brodin,

    2012-02-01

    Full Text Available Today, petroleum-based superabsorbents are widely used, but interest in renewable alternatives is on the rise. This study presents two wood-based absorbent materials suitable for various absorption applications as an alternative to petroleum-based products. Never-dried bleached kraft pulp was treated with TEMPO-oxidation, and new carboxylate and aldehyde groups were introduced. It was found that the aldehyde groups contributed to the wet integrity of the absorbent materials, possibly by the formation of hemiacetal bonds. After oxidation, the pulp fibers were gradually disintegrated, and size analysis showed that the disintegration rate was enhanced by an increase in the charge of the oxidant. Freeze drying produced a porous foam with a large surface area that enabled a rapid absorption rate as well as a reasonably high absorption capacity even for absorption under load. Air drying formed a compact film with a slow absorption rate but with a high final capacity for absorption.

  16. The Workshop on Microwave-Absorbing Materials for Accelerators

    Isidoro Campisi

    1993-05-01

    A workshop on the physics and applications of microwave-absorbing materials in accelerators and related systems was held at CEBAF February 22-24, 1993. The gathering brought together about 150 scientists and representatives of industries from all over the world. The main topics of discussion were the properties of ''absorbing'' materials and how the stringent conditions in an accelerator environment restrict the choice of usable material.

  17. Interaction of Interpolating Number-Coherent States with Atomic Systems

    Feng, Y; Solomon, A I; Feng, Yinqi; Fu, Hongchen

    1999-01-01

    Interpolating number-coherent states are new states of the radiation field which interpolate between number and coherent states, to which they reduce in appropriate limits. We study some fundamental features of the interaction of these new states with a atomic system in the framework of the Jaynes-Cummings model(JCM). The dynamical evolution of atomic population inversion, field entropy, the Q-function and photon number distribution properties are investigated in detail.

  18. Method of manufacturing neutron shielding and absorbing material

    Purpose: To manufacture neutron shielding and absorbing material uniformly dispersed with boron carbide. Method: Boron carbide particles are coated with copper, nickel or alloys thereof. Coating is preferably carried out by vacuum deposition or electroless plating. While the powder coated with a predetermined amount is molded and sintered, if the sintering density is low, reduction in the strength and the lowering in the heat conductivity are generally resulted to reduce the neutron shielding and absorbing performance. Therefore, a hot pressing is employed so as to obtain a composite product which is high in the density and uniformly dispersed. Hot isostatic pressing may also be used instead of hot pressing. For the mass production at an reduced cost, rolling of the composite product at a temperature higher than 300 0C is preferred since it can increase the density with preferred results. In this way, neutron shielding and absorbing material having a density of higher than 98 % of the theoretical level and uniformly dispersed can be manufactured. (Kamimura, M.)

  19. Simulated mixed absorbers and effective atomic numbers for attenuation

    K Karunakaran Nair; N Ramachandran; K K Abdullah; K M Varier

    2006-09-01

    The total -ray interaction crosss-sections on mixed absorbers were determined at 662 keV with a view to study the effective atomic numbers for -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 -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.

  20. Dysprosium hafnate as absorbing material for control rods

    Dysprosium hafnate is proposed as a promising absorbing material for control rods of thermal nuclear reactors. The properties of dysprosium hafnate pellets with different Dy and Hf contents are presented in this article. The fluorite phase is characterized by the density range 6.8-7.8 g/cm3 and; the thermal diffusivity achieves 0.58-0.83 mm2/s at 20 deg. C, thermal conductivity of 1.5-2.0 W/(K m) and TLEC of (8.4-8.6) x 10-6 K-1 at 20 deg. C. The temperature dependence of the thermophysical properties of dysprosium hafnate are presented. The neutron absorption efficiency of dysprosium hafnate was estimated in comparison with boron carbide. The radiation resistance of pellets after irradiation in the BOR-60 reactor is presented as well

  1. Low atomic number coating for XEUS silicon pore optics

    Lumb, D.H.; Cooper-Jensen, Carsten P.; Krumrey, M.; Cibik, L.; Christensen, Finn Erland; Collon, M.; Bavdaz, M.

    2008-01-01

    XEUS graze angles are presented. Reflectance is significantly enhanced for low energies when a low atomic number over-coating is applied. Modeling of the layer thicknesses and roughness is used to investigate the dependence on the layer thicknesses, metal and over coat material choices. We compare the...

  2. A definitive number of atoms on demand: controlling the number of atoms in a-few-atom magneto-optical trap

    Yoon, S; Park, S; Kim, J; Lee, J H; An, K; Yoon, Seokchan; Choi, Youngwoon; Park, Sangbum; Kim, Jaisoon; Lee, Jai-Hyung; An, Kyungwon

    2006-01-01

    A few 85Rb atoms were trapped in a micron-size magneto-optical trap with a high quadrupole magnetic-field gradient and the number of atoms was precisely controlled by suppressing stochastic loading and loss events via real-time feedback on the magnetic field gradient. The measured occupation probability of single atom was as high as 99%. Atoms up to five were also trapped with high occupation probabilities. The present technique could be used to make a deterministic atom source.

  3. Development of a new solid-state absorber material for dye-sensitized solar cell (DSSC)

    Swapna Lilly Cyriac; B Deepika; Bhaskaran Pillai; S V Nair; K R V Subramanian

    2014-05-01

    In contrast to the conventional DSSC systems, where the dye molecules are used as light harvesting material, here a solid-state absorber was used as a sensitizer in conjunction with the dye. The materials like ZnO and Al2O3 : C, which will show optically stimulated luminescence (OSL) upon irradiation were used as extremely thin absorber layers. This novel architecture allows broader spectral absorption, an increase in photocurrent, and hence, an improved efficiency because of the mobility of the trapped electrons in the absorber material after irradiation, to the TiO2 conduction band. Nanocrystalline mesoporous TiO2 photoanodes were fabricated using these solid-state absorber materials and after irradiation, a few number of samples were co-sensitized with N719 dye. On comparing both the dye loaded photoanodes (ZnO/TiO2 and Al2O3 : C/TiO2), it can be concluded from the present studies that, the Al2O3 : C is superior to ZnO under photon irradiation. Al2O3 : C is more sensitive to photon irradiation than ZnO and hence there can be more trap centres produced in Al2O3 : C.

  4. The Effect of Reflector with Sound-Absorbing Material on Supersonic Jet Noise

    Y.-H. KWEON; M. TSUCHIDA; Y. MIYAZATO; T. AOKI; H.-D. KIM; T. SETOGUCHI

    2005-01-01

    This paper describes an experimental work to investigate the effect of a reflector on supersonic jet noise radiated from a convergent-divergent nozzle with a design Mach number 2.0. In the present study, a metal reflector and reflectors made of three different sound-absorbing materials (grass wool and polyurethane foam) were employed,and the reflector size was varied. Acoustic measurement is carried out to obtain the acoustic characteristics such as frequency, amplitude of screech tone and overall sound pressure level (OASPL). A high-quality schlieren optical system is used to visualize the detailed structure of supersonic jet. The results obtained show that the acoustic characteristics of supersonic jet noise are strongly dependent upon the jet pressure ratio and the reflector size. It is also found that the reflector with sound-absorbing material reduces the screech tone amplitude by about 5-13dB and the overall sound pressure levels by about 2-5dB, compared with those of the metal reflector.

  5. A high absorbance material for solar collectors' applications

    In this work, we proposed a low cost material to be used as an excellent absorber for solar collectors, to increase its thermal efficiency by the high capacity to absorb solar radiation. The material, known as 'smoke black' (soot) can be obtained by the incomplete combustion of organic materials, such as the oxygen-acetylene, paraffin, or candles. A comparative analysis between the optical properties (reflectance, absorbance, and emissivity) measured on three covered copper surfaces (without paint, with a commercial matte black paint, and with smoke black) shows amazing optical results for the smoke black. Reflectance values of the smoke black applied over copper surfaces improves 56 times the values obtained from commercial black paints. High values of emissivity (E=0.9988) were measured on the surface covered with smoke black by spectrophotometry in the UV-VIS range, which represents about 7% of increment as compared with the value obtained for commercial black paints (E=0.938). The proposed high absorbance material can be easily applied on any kind of surfaces at low cost.

  6. Determination of atomic number and composition of human enamel

    The teeth are organs of complicated structure that consist, partly, of hard tissue containing in its interior the dental pulp, rich in vases and nerves. The main mass of the tooth is constituted by the dentine, which is covered with hard tissues and of epithelial origin called enamel. The dentine of the human teeth used in this work were completely removed and the teeth were cut with a device with a diamond disc. In this work the chemical composition of the human enamel was determined, which showed a high percentage of Ca and P, in agreement with the results found in the literature. The effective atomic number of the material and the half-value layer in the energy range of diagnostic X-ray beams were determined. Teeth could be used to evaluated the public's individual doses as well as for retrospective dosimetry what confirms the importance of their effective atomic number and composition determination. (author)

  7. Successive change regularity of actinide properties with atomic number

    The development and achievements on chemistry of actinide elements are summarised. The relations of properties of actinides to their electronic configurations of valence electronic shells are discussed. Some anomalies of solid properties, the radius contraction, the stable state effect of f7n-orbits (n = 0, 1, 2) and the tetrad effect of oxidation states, etc., with atomic number (Z) are described. 31 figures appended show directly the successive change regularity of actinide properties with Z

  8. Effective atomic numbers and electron density of dosimetric material

    Kaginelli S

    2009-01-01

    Full Text Available A novel method for determination of mass attenuation coefficient of x-rays employing NaI (Tl detector system and radioactive sources is described.in this paper. A rigid geometry arrangement and gating of the spectrometer at FWHM position and selection of absorber foils are all done following detailed investigation, to minimize the effect of small angle scattering and multiple scattering on the mass attenuation coefficient, m/r, value. Firstly, for standardization purposes the mass attenuation coefficients of elemental foils such as Aluminum, Copper, Molybdenum, Tantalum and Lead are measured and then, this method is utilized for dosimetric interested material (sulfates. The experimental mass attenuation coefficient values are compared with the theoretical values to find good agreement between the theory and experiment within one to two per cent. The effective atomic numbers of the biological substitute material are calculated by sum rule and from the graph. The electron density of dosimetric material is calculated using the effective atomic number. The study has discussed in detail the attenuation coefficient, effective atomic number and electron density of dosimetric material/biological substitutes.

  9. Thermoluminescence dosimetric properties and effective atomic numbers of window glass

    Highlights: • The TL properties of window glass were investigated. • The obtained results is potentially a good candidate for retrospective dosimetry. • The effective atomic number are close to human biological tissues. - Abstract: This work presents the main thermoluminescence (TL) dosimetric characteristics of commercial Thai transparent window glass. The amorphous structure of window glass was investigated by XRD. The glow curve revealed a peak (Tm) at 235 °C. The thermoluminescence response of window glass was studied after irradiation with photons in the absorb dose range of 0–14.05 mGy, which is of interest for the personal protection level of dosimetry. A linear response was obtained after both the first irradiation and the second irradiation. The minimum detectable dose of window glass was 0.15 mGy. The effective atomic number of window glass as a function of photon energy was calculated. The obtained results for the effective atomic number showed that it is very close to that of human biological tissues (Zeff = 6.7–8.4 at studied energy)

  10. Determining factors for high performance silicone rubber microwave absorbing materials

    Silicone rubber microwave absorbing materials (RMAMs) based on ferrite as the major absorbent were prepared by the mechanical blending method. The determining factors for the complex permittivity, complex permeability, and reflectivity of RMAM were thoroughly investigated with various samples including different crystal structures of Ba-ferrite (M-type, W-type, and Y-type), the ferrite with doped elements (Ba, Sr), the materials' thickness, the combination ratio of ferrite and carbonyl iron. The effects of surface modification and loading amount of ferrite on the mechanical properties, processing performance, and absorbing property of RMAM were also assessed. The results show that W-type Ba-ferrite based RMAM exhibits better absorbing property at high frequencies (8-18 GHz) than the other two barium ferrites (M-type and Y-type) based ones, and the absorbing property of RMAM based on Sr-ferrite is best. As the thickness of RMAM and the amount of absorbents increase, the absorption peak moves toward low frequency, the absorption frequency bandwidth is narrowed, and the reflectivity first decreases and later increases. The optimum thickness is 1.5-1.7 mm, and the amount of ferrite is 450 parts per hundreds of rubber (phr). Surface modification of the absorbent with silane coupling agent could improve the mechanical properties and processing performance of RMAM. It is concluded that there will be a synergistic effect when carbonyl iron (CI) is used in combination with Sr-ferrite (Sr-W) in an appropriate proportion. When the total volume fraction of absorbents is 51%, the optimum ratio of Cl to Sr-W is 17:34, the absorption frequency bandwidth (<-10 dB) is about 8 GHz, and the absorption area is -99 dB. - Highlights: → W-type ferrite exhibits better absorbing property than M-type and Y-type at 8-18 GHz. → Sr-W based RMAM has best absorbing property of Ba- and Sr-ferrite. → The optimum thickness of RMAM is 1.5-1.7 mm, and the amount of ferrite is 450 phr.

  11. New absorbent material acoustic based on kenaf’s fibre

    Ramis, J.

    2010-09-01

    Full Text Available Acoustic Standards in the building are responsible for, companies and individuals, propose new acoustic materials for the sound isolation. This paper presents a new sound-absorbent material, it is based on natural fibres, particularly fibres of kenaf. It also proposes an empirical model for this material, this models depends on the frequency. There are accepted models from the scientific community about mineral wool, glass wool, rock wool, foam or polyester fibre. Several of these models are empirical. They are obtained from the equation adjustments about the acoustic impedance and propagation constant behaviour, depending upon the flow resistivity, fibre’s diameter and density. There are even standards like UNE-EN 12354-6 where these models are accepted under certain limitations like the fundamental basis as in the materials’ acoustics behaviour prediction. From the various tests conducted in the laboratory, empirical equations are proposed for this new acoustic material. In addition, there has been a first approach to validate this model in combination with a micro-structural model, based on the steps taken by Bies-Hansen (1, which allows us to obtain the value of the resistance to flow.

    El carácter marcadamente prestacional de las normativas acústicas en la edificación abre el camino a la propuesta, por parte de empresas y particulares, de nuevos materiales acústicos susceptibles de ser utilizados en el ámbito de la acústica de la edificación. Éste es el caso que nos ocupa en el presente trabajo en el que se presenta un nuevo material acústico absorbente basado en fibras vegetales, concretamente el kenaf. Además se propone un modelo empírico de modelización del comportamiento absorbente de varias composiciones de este material en función de la frecuencia. Existen modelos de diferentes lanas minerales, lanas de roca, lanas de vidrio, espumas o lanas de poliéster. Algunos de estos modelos —llamados empíricos— se

  12. Absorber materials for low-energy neutrons - Theoretical and experimental studies

    Absorber materials for low-energy neutrons are studied in the theoretical framework of quantum mechanics with a complex potential. Analytical expressions and numerical calculations of the neutron reflectivity for perpendicular and isotropic motion towards a surface for four different material classes are presented. Comparative experimental studies of four absorber materials have been carried out: Polyethylene, titanium, boron-10 and lithium stearate. In a quasi-storage experiment with ultracold neutrons the latter material features the highest absorption property.

  13. Energy dependence of the effective atomic number of soils

    The effective atomic number (Zsub(eff)) of five different soils have been calculated for different photon interaction processes to check the variation in Zsub(eff) with photon energy (10 keV to 100 MeV). For the total interaction process Zsub(eff) first increases with the increase in energy to 30-40 keV and then decreases sharply upto 400-500 keV and slowly further upto 1500-2000 keV beyond which there is small but continuous increase in Zsub(eff) with further increases in energy to 100 MeV. For photoelectric interaction Zsub(eff) increases in low energy region and then becomes independent of energy whereas for Compton scattering except below 100 keV, Zsub(eff) is constant upto 100 MeV. In case of pair production, Zsub(eff) decreases upto 3-4 MeV beyond which it becomes constant. (author). 10 refs., 4 figs

  14. Disk emission and absorption lines in LMXB. Note on the physical conditions of an absorbing material

    Rozanska, Agata

    2014-01-01

    We show that the continuum X-ray spectrum of 4U 1630-472 with iron absorption lines can be satisfactorily modeled by the spectrum from an accretion disk atmosphere. We performed full radiative transfer calculations using our code ATM21 to model the emission from an accretion disk surface that is seen at different viewing angles. Computed models are then fitted to the high-resolution X-ray spectra of 4U 1630-472 obtained by {\\it Suzaku} satellite. Absorption lines of highly ionized iron originating in a hot accretion-disk atmospheres are important part of the observed line profile, and can be an alternative or complementary explanation to the wind model usually favored for this type of sources. Next, assuming that absorption lines originate from the wind illuminated by X-ray central source in LMXBs, we can put constrains on the wind location only if we know the volume density number of the absorbing material. There are a few derivations of the distance to the wind in X-ray binaries. We show here, that the dens...

  15. Large atom number Bose-Einstein condensate of sodium

    van der Stam, K M R; Meppelink, R; Vogels, J M; Van der Straten, P

    2006-01-01

    We describe the setup to create a large Bose-Einstein condensate containing more than 120x10^6 atoms. In the experiment a thermal beam is slowed by a Zeeman slower and captured in a dark-spot magneto-optical trap (MOT). A typical dark-spot MOT in our experiments contains 2.0x10^10 atoms with a temperature of 320 microK and a density of about 1.0x10^11 atoms/cm^3. The sample is spin polarized in a high magnetic field, before the atoms are loaded in the magnetic trap. Spin polarizing in a high magnetic field results in an increase in the transfer efficiency by a factor of 2 compared to experiments without spin polarizing. In the magnetic trap the cloud is cooled to degeneracy in 50 s by evaporative cooling. To suppress the 3-body losses at the end of the evaporation the magnetic trap is decompressed in the axial direction.

  16. Effect of different absorbing materials on the performance of basin solar still under Libyan climate conditions

    This experimental study deals with a single-basin solar still using various absorbing materials with and without black painting. Different types of absorbing materials with and without black painting were used to enhance the solar still productivity through improvement in absorptivity. These materials are steel and aluminum with and without black painting and rubber. Two identical solar stills were manufactured using locally available materials. All the results were compared together to reach the best absorbing materials with and without painting that can be used for solar still. it was found that the rubber absorber has the highest water collection during daytime, followed by the black painted steel absorber, then by black painted aluminum absorber and steel without painting absorber. The average enhancement in the daily productivity was about 50% for the rubber absorber compared with the black painted aluminum absorber and about 43% for the rubber absorber compared with the black painted steel absorber.(author)

  17. Quantitative effective atomic number imaging using simultaneous x-ray absorption and phase shift measurement

    A scanning type x-ray imaging system which measures the absorption and differential phase shift in a material quantitatively and simultaneously has been developed. The absorption and differential phase are used to obtain the effective atomic number of organic material samples which closely reflects their chemical composition. An effective atomic number map of polymer fibers has been obtained. The experimentally obtained effective atomic numbers of these polymers agree well with the corresponding calculated values.

  18. The Direct-Zeff software for direct calculation of mass attenuation coefficient, effective atomic number and effective electron number

    Highlights: • Determination of effective atomic and effective electron number is very important. • The Direct-Zeff software calculates effective atomic and effective electron number. • The Direct-Zeff software calculates for total and partial photon interactions. • Calculations of The Direct-Zeff are in good agreement with experimental results. - Abstract: Determination of the mass attenuation coefficient, μ/ρ, the effective atomic number, Zeff, and the effective electron number, Neff, is very important in the fields of nuclear diagnostics, radiation protection, nuclear medicine and radiation dosimetry. In this work, the Direct-Zeff software was developed for the computation of the mass attenuation coefficient, the effective atomic number and the effective electron number per unit mass in the energy range 1 keV–100 GeV. The values of the Zeff, Neff and μ/ρ can be determined for total photon interaction with and without coherent interaction as well as partial photon interactions such as coherent scattering, incoherent scattering, photoelectric absorption and pair production by using the Direct-Zeff software. The accuracy of the Direct-Zeff software has been demonstrated by comparing the calculated data and the experimental values for the various materials. The Direct-Zeff software can be freely obtained by contacting with the authors

  19. Sub-Poissonian atom number fluctuations by three-body loss in mesoscopic ensembles

    Whitlock, S; Spreeuw, R J C

    2009-01-01

    We show that three-body loss of trapped atoms leads to sub-Poissonian atom number fluctuations. We prepare hundreds of dense ultracold ensembles in an array of magnetic microtraps which undergo rapid three-body decay. The shot-to-shot fluctuations of the number of atoms per trap are sub-Poissonian, for ensembles comprising 50--300 atoms. The measured relative variance or Fano factor $F=0.53\\pm 0.22$ agrees very well with the prediction by an analytic theory ($F=3/5$) and numerical calculations. These results will facilitate studies of quantum information science with mesoscopic ensembles.

  20. Sub-Poissonian atom-number fluctuations by three-body loss in mesoscopic ensembles.

    Whitlock, S; Ockeloen, C F; Spreeuw, R J C

    2010-03-26

    We show that three-body loss of trapped atoms leads to sub-Poissonian atom-number fluctuations. We prepare hundreds of dense ultracold ensembles in an array of magnetic microtraps which undergo rapid three-body decay. The shot-to-shot fluctuations of the number of atoms per trap are sub-Poissonian, for ensembles comprising 50-300 atoms. The measured relative variance or Fano factor F=0.53+/-0.22 agrees very well with the prediction by an analytic theory (F=3/5) and numerical calculations. These results will facilitate studies of quantum information science with mesoscopic ensembles. PMID:20366518

  1. Research and application of kapok fiber as an absorbing material: A mini review

    Yian Zheng; Jintao Wang; Yongfeng Zhu; Aiqin Wang

    2015-01-01

    Kapok fiber corresponds to the seed hairs of the kapok tree (Ceiba pentandra),and is a typical cellulosic fiber with the features of thin cell wall,large lumen,low density and hydrophobicoleophilic properties.As a type of renewable natural plant fiber,kapok fiber is abundant,biocompatible and biodegradable,and its full exploration and potential application have received increasing attention in both academic and industrial fields.Based on the structure and properties of kapok fiber,this review provides a summary of recent research on kapok fiber including chemical and physical treatments,kapok fiber-based composite materials,and the application of kapok fiber as an absorbent material for oils,metal ions,dyes,and sound,with special attention to its use as an oil-absorbing material,one predominant application of kapok fiber in the coming future.

  2. Influence of microstructure on properties of Ni–Zn ferrite radio-absorbing materials

    In this work there have been carried out studies in the radiophysical characteristics of the samples of Ni–Zn ferrite radio-absorbing materials, obtained by the ceramic method under different technological conditions. There has been established the influence of microstructure on the electromagnetic losses of Ni–Zn ferrite radio-absorbing materials. The results indicate that the coarse-grained structure leads to an increase of radio-absorbing capacity at frequencies below 30 MHz. It can be explained by the resonance of domain boundaries. - Highlights: • Addition of Bi2O3 up to 1 mass% leads to increasing grain sizes of Ni-Zn ferrites. • Coarse-grained structure is achieved adding ferrite particles of a large fraction. • Coarse-grained structure leads to increasing absorbing capacity at low frequencies. • It can be explained by the resonance of domain boundaries

  3. Comparison of silicon oxide and silicon carbide absorber materials in silicon thin-film solar cells

    Walder Cordula; Kellermann Martin; Wendler Elke; Rensberg Jura; von Maydell Karsten; Agert Carsten

    2015-01-01

    Since solar energy conversion by photovoltaics is most efficient for photon energies at the bandgap of the absorbing material the idea of combining absorber layers with different bandgaps in a multijunction cell has become popular. In silicon thin-film photovoltaics a multijunction stack with more than two subcells requires a high bandgap amorphous silicon alloy top cell absorber to achieve an optimal bandgap combination. We address the question whether amorphous silicon carbide (a-SiC:H) or ...

  4. Effective atomic numbers of some tissue substitutes by different methods: a comparative study

    Effective atomic numbers of some human organ tissue substitutes such as polyethylene terephthalate, red articulation wax, paraffin 1, paraffin 2, bolus, pitch, polyphenylene sulfide, polysulfone, polyvinylchloride, and modeling clay have been calculated by four different methods like Auto-Zeff, direct, interpolation, and power law. It was found that the effective atomic numbers computed by Auto-Zeff, direct and interpolation methods were in good agreement for intermediate energy region (0.1 MeV eff was observed in photo-electric and pair-production regions. Effective atomic numbers computed by power law were found to be close to direct method in photo-electric absorption region. The Auto-Zeff, direct and interpolation methods were found to be in good agreement for computation of effective atomic numbers in intermediate energy region (100 keV < E < 10 MeV). The direct method was found to be appropriate method for computation of effective atomic numbers in photo-electric region (10 keV < E < 100 keV). The tissue equivalence of the tissue substitutes is possible to represent by any method for computation of effective atomic number mentioned in the present study. An accurate estimation of Rayleigh scattering is required to eliminate effect of molecular, chemical, or crystalline environment of the atom for estimation of gamma interaction parameters. (author)

  5. Sub-Poissonian atom number fluctuations using light-assisted collisions

    Sortais, Y R P; Bourgain, R; Browaeys, A

    2011-01-01

    We investigate experimentally the number statistics of a mesoscopic ensemble of cold atoms in a microscopic dipole trap, and find that the atom number fluctuations are reduced with respect to a Poisson distribution due to light-assisted two-body collisions. For numbers of atoms larger than 2, we measure a reduction factor (Fano factor) close to 0.75. We analyze this fact by a general stochastic model describing the competition between the loading of the trap from a reservoir of cold atoms and multi-body losses, which leads to a master equation. The model indicates that we have reached the ultimate level of reduction in number fluctuations achievable in our experimental regime.

  6. Influence of the electron's anomalous magnetic dipole moment on high-atomic number atoms

    Super heavy atoms ( Z > 100 ) are usually studied in the context of the so-called Quantum Electrodynamics of Strong Fields. In this theory the problem of the singularity in the electron energy whenever Z > 137 is overcome. This is done by considering the finite size of the nucleus and leads to interesting phenomena, such as the spontaneous production of positrons. Here, we show that, taking into account the contribution from the Anomalous Magnetic Dipole Moment of the electron ( by means of an effective theory ), within a point nucleus model, is a sufficient condition to obtain regular wave functions and physically acceptable energy values for Z > 137. (author)

  7. Neutron Absorbing Ability Variation in Neutron Absorbing Material Caused by the Neutron Irradiation in Spent Fuel Storage Facility

    In spent fuel storage facility like high density spent fuel storage racks and dry storage casks, spent fuels are stored with neutron absorbing materials installed as a part of those facilities, and they are used for absorbing neutrons emitted from spent fuels. Usually structural material with neutron absorbing material of racks and casks are located around spent fuels, so it is irradiated by neutrons for long time. Neutron absorbing ability could be changed by the variation of nuclide composition in neutron absorbing material caused by the irradiation of neutrons. So, neutron absorbing materials are continuously faced with spent fuels with boric acid solution or inert gas environment. Major nuclides in neutron absorbing material are Al27, C12, B11, B10 and they are changed to numerous other ones as radioactive decay or neutron absorption reaction. The B10 content in neutron absorbing material dominates the neutron absorbing ability, so, the variation of nuclide composition including the decrease of B10 content is the critical factor on neutron absorbing ability. In this study, neutron flux in spent fuel, the activation of neutron absorbing material and the variation of nuclide composition are calculated. And, the minimum neutron flux causing the decrease of B10 content is calculated in spent fuel storage facility. Finally, the variation of neutron multiplication factor is identified according to the one of B10 content in neutron absorbing material. The minimum neutron flux to impact the neutron absorbing ability is 1010 order, however, usual neutron flux from spent fuel is 108 order. Therefore, even though neutron absorbing material is irradiated for over 40 years, B10 content is little decreased, so, initial neutron absorbing ability could be kept continuously

  8. Experimental Evaluation Of A Single-basin Solar Still Using Different Absorbing Materials: An Overview

    T.R.TELTUMBADE,

    2011-04-01

    Full Text Available Single-basin solar stills can be used for water desalination. Probably, the are considered the best solution for water production in remote,arid to semi-arid, small communities, where fresh water isunavailable.however,the amount of distilled water produced per unit area is somewhat low which makes the single-basin solar still unacceptable in some instances. The purpose of this paper is to study the effect of using different absorbing materials in a solar still, and thuds enhance the productivity of water. Experimental result show that the productivity of distilled water was enhance for some matereals.

  9. In-line phase contrast for weakly absorbing materials with a microfocus x-ray source

    Zhang Di; Li Zheng; Huang Zhi-Feng; Yu Ai-Min; Sha Wei

    2006-01-01

    For weakly absorbing materials, image contrast can be enhanced by phase contrast in formation. The effectiveness of the in-line phase contrast technique relies on its ability to record intensity data which contain information on the x-ray's phase shift. Four kinds of approaches to the relationship between intensity distribution and phase shift are reviewed and discussed. A micro-focal x-ray source with high geometrical magnification is used to acquire phase contrast images. A great improvement on image quality is shown and geometrical parameters are modified for comparison between different imaging positions.

  10. A New CMC-AA Resin/Inorganic-gel Super Absorbent Material

    2006-01-01

    A super absorbent material was prepared with the super absorbent resin ( SAR ) and inorganicgel.The SAR of the carboxymethyl cellulose grafting acrylic acid ( CMC-AA ) was copolymer synthesized using the method of inverse-phase suspension polymerization. The influences of the monomer concentration, neutralization degree, the initiator, dispersion agent, cross-linking agent, reaction and drying temperature on the grafting copolymer properties were examined.Meanwhlie, its properties was investigated and the model for absorption mechanism of this absorbent composite was proposed.

  11. Dynamic Response and Fracture Mechanism of a Novel Structural Radar Absorbing Material

    CAO Mao-Sheng; ZHOU Wei; QU Gui-Min; RONG Ji-Li

    2008-01-01

    @@ A novel structural radar absorbing material (SRAM), which gives the normal resin-base composites new function, is prepared. The dynamic compressive tests of SRAM are carried out in both in-plane and normal directions of composites by means of the split Hopkinson pressure bar (SHPB). In the compressive test along in-plane direction, failure occurs at the interface between a fibre and the matrix. A fracture mode and mechanism was proposed to explain these results. The addition of absorbing particles results in the deterioration of the compressive properties. However, there is no obvious decrease on compressive strength of SRAM with the radar absorbing properties.

  12. Effective atomic numbers and electron densities of bioactive glasses for photon interaction

    Shantappa, Anil; Hanagodimath, S. M.

    2015-08-01

    This work was carried out to study the nature of mass attenuation coefficient of bioactive glasses for gamma rays. Bioactive glasses are a group of synthetic silica-based bioactive materials with unique bone bonding properties. In the present study, we have calculated the effective atomic number, electron density for photon interaction of some selected bioactive glasses viz., SiO2-Na2O, SiO2-Na2O-CaO and SiO2-Na2O-P2O5 in the energy range 1 keV to 100 MeV. We have also computed the single valued effective atomic number by using XMuDat program. It is observed that variation in effective atomic number (ZPI, eff) depends also upon the weight fractions of selected bioactive glasses and range of atomic numbers of the elements. The results shown here on effective atomic number, electron density will be more useful in the medical dosimetry for the calculation of absorbed dose and dose rate.

  13. Measurement of effective atomic number of gunshot residues using scattering of gamma rays

    Better understanding of gunshot residues and the major elemental composition would be valuable to forensic scientists for their analysis work and interpretation of results. In the present work, the effective atomic numbers of gunshot residues (cartridge case, bullet core, bullet jacket and gunpowder) were analyzed using energy dispersive X-ray analysis (EDX). The scattering of 59.54 keV gamma rays is studied using a high-resolution HPGe detector. The experiment is performed on various elements with atomic number in the 4≤Z≤82. The intensity ratio of coherent to Compton scattered peaks, corrected for photo-peak efficiency of gamma detector and absorption of photons in the sample and air, is plotted as a function of atomic number and constituted a best-fit-curve. From this fit-curve, the respective effective atomic numbers of gunshot residues are determined. - Highlights: • Values of Zeff depend on the chemical content of the investigated gunshot residues. • The agreement of measured values of effective atomic numbers with theoretical calculations is quite satisfactory. • The present calculations of Zeff have thrown new light on forensic science

  14. Effective atomic numbers and electron densities of bioactive glasses for photon interaction

    Shantappa, Anil, E-mail: anilmalipatil@yahoo.co.in [Department of Physics, Veerappa Nisty Engineering College, Shorapur-585220, KARNATAKA (India); Hanagodimath, S. M., E-mail: smhmath@rediffmail.com [Department of Physics Gulbarga University, Gulbarga-585106, KARNATAKA (India)

    2015-08-28

    This work was carried out to study the nature of mass attenuation coefficient of bioactive glasses for gamma rays. Bioactive glasses are a group of synthetic silica-based bioactive materials with unique bone bonding properties. In the present study, we have calculated the effective atomic number, electron density for photon interaction of some selected bioactive glasses viz., SiO{sub 2}-Na{sub 2}O, SiO{sub 2}-Na{sub 2}O-CaO and SiO{sub 2}-Na{sub 2}O-P{sub 2}O{sub 5} in the energy range 1 keV to 100 MeV. We have also computed the single valued effective atomic number by using XMuDat program. It is observed that variation in effective atomic number (Z{sub PI,} {sub eff}) depends also upon the weight fractions of selected bioactive glasses and range of atomic numbers of the elements. The results shown here on effective atomic number, electron density will be more useful in the medical dosimetry for the calculation of absorbed dose and dose rate.

  15. Quantum nondemolition measurement of photon-number distribution for a weak cavity field with resonant atoms

    郑仕标

    2003-01-01

    We propose a quantum nondemolition measurement of the photon-number distribution for a weak cavity field with no more than two photons. The scheme is based on the resonant interaction of atoms with the cavity field, and thus the required interaction time is much shorter than that using dispersive interaction. This is important in view of decoherence. Our scheme can also be used to generate even and odd coherent states for a weak cavity field with resonant atoms.

  16. Temperature and number evolution of cold cesium atoms inside a wall-coated glass cell

    黄家强; 张建伟; 王时光; 王力军

    2015-01-01

    We report an experimental study on the temperature and number evolution of cold cesium atoms diffusively cooled inside a wall-coated glass cell by measuring the absorption profile of the 62S1/2 (F=4)→62P3/2(F0=5) transition line with a weak probe laser in the evolution process. We found that the temperature of the cold atoms first gradually decreases from 16 mK to 9 mK, and then rapidly increases. The number of cold atoms first declines slowly from 2.1 × 109 to 3.7 × 108 and then falls drastically. A theoretical model for the number evolution is built and includes the instantaneous temperature of the cold atoms and a fraction p, which represents the part of cold cesium atoms elastically reflected by the coated cell wall. The theory is overall in good agreement with the experimental result, and a nonzero value is obtained for the fraction p, which indicates that the cold cesium atoms are not all heated to the ambient temperature by a single collision with the coated cell wall. These results can provide helpful insight for precision measurements based on diffuse laser cooling.

  17. Impact characteristics of energy absorbing materials for radioactive material transport packages

    A series of high-velocity impact tests using grout as the package energy-absorbing material was successfully carried out. The purpose of these tests was to characterize the dynamic behavior of grout material when used as an energy-absorbing material for packages. These package-impact tests were simulated accurately with the dynamic finite element code DYNA, using appropriate grout material properties. The need to invoke the grout damage curve illustrates the fact that the grout mix under study undergoes a transition where the grout retains its full strength at relatively low impact velocity to a diminished strength where progressive debonding and pulverization takes place as the impact velocity increases. The transitional velocity range is a function of a particular grout mix as well as impact conditions. Laboratory tests of the grout mix that include the failure region and different failure modes should be an integral part of the investigation process to accurately correlate package benchmark tests with analytical models. (J.P.N.)

  18. Absorber Materials for Transition-Edge Sensor X-ray Microcalorimeters

    Brown, Ari-David; Bandler, Simon; Brekosky, Regis; Chervenak, James; Figueroa-Feliciano, Enectali; Finkbeiner, Fred; Sadleir, Jack; Iyomoto, Naoko; Kelley, Richard; Kilbourne, Caroline; Porter, F. Scott; Smith, Stephen; Saab, Tarek; Sadleir, Jac,

    2007-01-01

    Arrays of superconducting transition-edge sensors (TES) can provide high spatial and energy resolution necessary for x-ray astronomy. High quantum efficiency and uniformity of response can be achieved with a suitable absorber material, in which absorber x-ray stopping power, heat capacity, and thermal conductivity are relevant parameters. Here we compare these parameters for bismuth and gold. We have fabricated electroplated gold, electroplated gold/electroplated bismuth, and evaporated gold/evaporated bismuth 8x8 absorber arrays and find that a correlation exists between the residual resistance ratio (RRR) and thin film microstructure. This finding indicates that we can tailor absorber material conductivity via microstructure alteration, so as to permit absorber thermalization on timescales suitable for high energy resolution x-ray microcalorimetry. We show that by incorporating absorbers possessing large grain size, including electroplated gold and electroplated gold/electroplated bismuth, into our current Mo/Au TES, devices with tunable heat capacity and energy resolution of 2.3 eV (gold) and 2.1 eV (gold/bismuth) FWHM at 6 keV have been fabricated.

  19. Effective atomic numbers and mass attenuation coefficients of some thermoluminescent dosimetric compounds for total photon interaction

    Effective atomic numbers for total gamma-ray interaction with some selected thermoluminescent dosimetric compounds such as barium acetate, barium sulfate, calcium carbonate, calcium sulfate, calcium sulfate dihydrate, cadmium sulfate (anhydrous), cadmium sulfate, strontium sulfate, and lithium fluoride have been calculated in the 1-keV to 20-MeV energy region. Experimental mass attenuation coefficients and effective atomic numbers for these compounds at selected photon energies of 26.3, 33.2, 59.54, and 661.6 keV have been obtained from good geometry transmission measurements and compared with theoretical values. The effect of absorption edge on effective atomic numbers and its variation with energy, and nonvalidity of the Bragg's mixture rule at incident photon energies closer to the absorption edges of constituent elements of compounds are discussed

  20. Effective atomic numbers for photon energy absorption of some low-Z substances of dosimetric interest

    Effective atomic numbers for photon energy absorption (ZPEAeff) and effective atomic numbers for photon interaction (ZPIeff) of some low-Z substances of dosimetric interest such as A-150 tissue-equivalent plastic (A150TEP), alanine, bakelite, Gafchromic sensor (GS), plastic scintillator (PS), polyethylene, mylar, polystyrene, perspex, radiochromic dye film nylon base (RDF : NB), tissue-equivalent gas-methane based (TEG : MB) and tissue-equivalent gas-propane based (TEG : PB) have been calculated by a direct method in the energy region of 1 keV-20 MeV. Experimental mass attenuation coefficients and ZPIeff of some of these substances at selected photon energies of 26.34, 33.2, and 59.54 keV have been obtained and compared with theoretical values. The ZPEAeff and ZPIeff values steadily increases up to 6-15 keV, and then they steadily decrease up to 600-1500 keV for all the substances studied. From 1.5 MeV, the values increases with increase in energy up to 20 MeV. Significant differences up to 33.68% exist between ZPIeff and the ZPEAeff in the energy region of 10-150 keV. The single effective atomic numbers obtained using the program XMuDat (ZXMUDATeff ) are found to be significantly higher compared to those of ZPEAeff and ZPIeff values in the entire energy of interest for all the substances studied. The directly calculated ZPEAeff and ZPIeff values vary with energy compared to the energy-independent effective atomic numbers predicted by various theoretical expressions. The effects of absorption edges on effective atomic numbers and their variation with photon energy and the possibility of defining two set values of effective atomic numbers below the absorption edges of elements present in the composite substances are discussed

  1. The effective atomic numbers of some biomolecules calculated by two methods: A comparative study

    Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

    2009-01-01

    The effective atomic numbers Z(eff) of some fatty acids and amino acids have been calculated by two numerical methods, a direct method and an interpolation method, in the energy range of 1 keV-20 MeV. The notion of Z(eff) is given a new meaning by using a modern database of photon interaction cross...... constant and equal to the mean atomic number of the material. Wherever possible, the calculated values of Z(eff) are compared with experimental data....

  2. Dynamical decoherence in a cavity with a large number of two-level atoms

    Frasca, Marco

    2003-01-01

    We consider a large number of two-level atoms interacting with the mode of a cavity in the rotating-wave approximation (Tavis-Cummings model). We apply the Holstein-Primakoff transformation to study the model in the limit of the number of two-level atoms, all in their ground state, becoming very large. The unitary evolution that we obtain in this approximation is applied to a macroscopic superposition state showing that, when the coherent states forming the superposition are enough distant, t...

  3. The splitting of atomic orbitals with a common principal quantum number revisited: np vs. ns.

    Katriel, Jacob

    2012-04-14

    Atomic orbitals with a common principal quantum number are degenerate, as in the hydrogen atom, in the absence of interelectronic repulsion. Due to the virial theorem, electrons in such orbitals experience equal nuclear attractions. Comparing states of several-electron atoms that differ by the occupation of orbitals with a common principal quantum number, such as 1s(2) 2s vs. 1s(2) 2p, we find that although the difference in energies, ΔE, is due to the interelectronic repulsion term in the Hamiltonian, the difference between the interelectronic repulsions, ΔC, makes a smaller contribution to ΔE than the corresponding difference between the nuclear attractions, ΔL. Analysis of spectroscopic data for atomic isoelectronic sequences allows an extensive investigation of these issues. In the low nuclear charge range of pertinent isoelectronic sequences, i.e., for neutral atoms and mildly positively charged ions, it is found that ΔC actually reverses its sign. About 96% of the nuclear attraction difference between the 6p (2)P and the 6s (2)S states of the Cs atom is cancelled by the corresponding interelectronic repulsion difference. From the monotonic increase of ΔE with Z it follows (via the Hellmann-Feynman theorem) that ΔL > 0. Upon increasing the nuclear charge along an atomic isoelectronic sequence with a single electron outside a closed shell from Z(c), the critical charge below which the outmost electron is not bound, to infinity, the ratio ΔC/ΔL increases monotonically from lim(Z→Z(c)(+))ΔC/ΔL=-1 to lim(Z→∞)ΔC/ΔL=1. These results should allow for a more nuanced discussion than is usually encountered of the crude electronic structure of many-electron atoms and the structure of the periodic table. PMID:22502506

  4. States interpolating between number and coherent states and their interaction with atomic systems

    Using the eigenvalue definition of binomial states we construct new intermediate number-coherent states which reduce to number and coherent states in two different limits. We reveal the connection of these intermediate states with photon-added coherent states and investigate their non-classical properties and quasiprobability distributions in detail. It is of interest to note that these new states, which interpolate between coherent states and number states, neither of which exhibit squeezing, are nevertheless squeezed states. A scheme to produce these states is proposed. We also study the interaction of these states with atomic systems in the framework of the two-photon Jaynes-Cummings model, and describe the response of the atomic system as it varies between the pure Rabi oscillation and the collapse-revival mode and investigate field observables such as photon number distribution, entropy and the Q-function. (author)

  5. Selected K and L X-Ray mass attenuation coefficients for low atomic number materials

    X-ray attenuation coefficients for low atomic mumbers elements were obtained for characteristic K and L X-ray of a number of selected elements using the fitting of a third degree polynomial to the values tabulated by Storm and Israel

  6. PREPARATION OF OXALATES OF METALS OF ATOMIC NUMBER GREATER THAN 88

    Duffield, R.B.

    1959-02-01

    A method is presented for the preparation of oxalates of metals of atomic number greater than 88. A solid peroxide of the heavy metal is contacted with an aqueous oxalic acid solution ai a temperature of about 50 C for a period of time sufficient to form the insoluble metal oxalate which is subsequentiy recovered as a pures crystalline compound.

  7. Cheminoes: A Didactic Game to Learn Chemical Relationships between Valence, Atomic Number, and Symbol

    Moreno, Luis F.; Hincapié, Gina; Alzate, María Victoria

    2014-01-01

    Cheminoes is a didactic game that enables the meaningful learning of some relations between concepts such as chemical element, valence, atomic number, and chemical symbol for the first 36 chemical elements of the periodic system. Among the students who have played the game, their opinions of the activity were positive, considering the game to be a…

  8. Knitted radar absorbing materials (RAM) based on nickel-cobalt magnetic materials

    Teber, Ahmet; Unver, Ibrahim; Kavas, Huseyin; Aktas, Bekir; Bansal, Rajeev

    2016-05-01

    There has been a long-standing interest in the development of flexible, lightweight, thin, and reconfigurable radar absorbing materials (RAM) for military applications such as camouflaging ground-based hardware against airborne radar observation. The use of polymeric Polyacrylonitrile (PAN) fabrics as a host matrix for magnetic metal nano-particles (either at the yarn-stage or after weaving the fabric) for shielding and absorbing applications has been described in the literature. In our experimental investigation, the relative concentrations of Nickel and Cobalt as well as the coating time are varied with a view to optimizing the microwave absorption characteristics of the resulting PAN-based composite material in the radar-frequency bands (X, Ku, and K). It is found that the PAN samples with the shortest coating time have the best return losses (under -20 dB return loss over a moderate bandwidth).

  9. Nanostructured composites based on carbon nanotubes and epoxy resin for use as radar absorbing materials

    Silva, Valdirene Aparecida [Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil); Folgueras, Luiza de Castro; Candido, Geraldo Mauricio; Paula, Adriano Luiz de; Rezende, Mirabel Cerqueira, E-mail: mirabelmcr@iae.cta.br [Instituto de Aeronautica e Espaco (IAE), Sao Jose dos Campos, SP (Brazil). Div. de Materiais; Costa, Michelle Leali [Universidade Estadual Paulista Julio de Mesquita Filho (DMT/UNESP), Guaratingueta, SP (Brazil). Dept. de Materiais e Tecnologia

    2013-07-01

    Nanostructured polymer composites have opened up new perspectives for multifunctional materials. In particular, carbon nanotubes (CNTs) present potential applications in order to improve mechanical and electrical performance in composites with aerospace application. The combination of epoxy resin with multi walled carbon nanotubes results in a new functional material with enhanced electromagnetic properties. The objective of this work was the processing of radar absorbing materials based on formulations containing different quantities of carbon nanotubes in an epoxy resin matrix. To reach this objective the adequate concentration of CNTs in the resin matrix was determined. The processed structures were characterized by scanning electron microscopy, rheology, thermal and reflectivity in the frequency range of 8.2 to 12.4 GHz analyses. The microwave attenuation was up to 99.7%, using only 0.5% (w/w) of CNT, showing that these materials present advantages in performance associated with low additive concentrations (author)

  10. Carbon nanotube scaffolds with controlled porosity as electromagnetic absorbing materials in the gigahertz range.

    González, M; Crespo, M; Baselga, J; Pozuelo, J

    2016-05-19

    Control of the microscopic structure of CNT nanocomposites allows modulation of the electromagnetic shielding in the gigahertz range. The porosity of CNT scaffolds has been controlled by two freezing protocols and a subsequent lyophilization step: fast freezing in liquid nitrogen and slow freezing at -20 °C. Mercury porosimetry shows that slowly frozen specimens present a more open pore size (100-150 μm) with a narrow distribution whereas specimens frozen rapidly show a smaller pore size and a heterogeneous distribution. 3D-scaffolds containing 3, 4, 6 and 7% CNT were infiltrated with epoxy and specimens with 2, 5 and 8 mm thicknesses were characterized in the GHz range. Samples with the highest pore size and porosity presented the lowest reflected power (about 30%) and the highest absorbed power (about 70%), which allows considering them as electromagnetic radiation absorbing materials. PMID:27152472

  11. Efficient positioning of absorbing material in complex systems by using the Patch Transfer Function method

    Totaro, N.; Guyader, J. L.

    2012-06-01

    Given the need to decrease energy consumption in the automobile industry, vehicle weight has become an important issue. Regarding acoustic comfort, the weight of noise reduction devices must be minimized inside vehicle compartments. Consequently, these devices, for example those using poro-elastic materials, must be designed carefully to maximize their influence on noise reduction. The present paper describes a method developed to obtain an efficient positioning of a given surface (or mass) of absorbing material characterized by its surface impedance. This technique is based on the Patch Transfer Function method used to couple complex vibro-acoustic sub-domains and which has been successfully applied in the European ViSPeR and Silence projects. First, a numerical analysis of the possibilities of this method is performed on a non-rectangular cavity with rigid walls after which an experimental validation of this numerical analysis is performed to evaluate the accuracy of the method under real conditions.

  12. Dielectric microwave absorbing material processed by impregnation of carbon fiber fabric with polyaniline

    Luiza de Castro Folgueras

    2007-03-01

    Full Text Available It is a known fact that the adequate combination of components and experimental conditions may produce materials with specific requirements. This study presents the effect of carbon fiber fabric impregnation with polyaniline conducting polymer aiming at the radar absorbing material processing. The experiments consider the sample preparation with one and two impregnations. The prepared samples were evaluated by reflectivity measurements, in the frequency range of 8-12 GHz and scanning electron microscopy analyses. The correlation of the results shows that the quantity of impregnated material influences the performance of the processed microwave absorber. This study shows that the proposed experimental route provides flexible absorbers with absorption values of the incident radiation close to 87%.

  13. High-performance experimental apparatus for large atom number 87Rb Bose-Einstein condensates

    We describe our high-performance experimental apparatus for producing large atom number 87Rb Bose-Einstein condensates by using a double magneto-optical trap (MOT) system that consists of a two-dimensional MOT (2D MOT) and a three-dimensional MOT (3D MOT). As an atomic beam source for loading the 3D MOT, we use a unique 2D MOT system with two-color pushing beams, which increase the loading rate and the total number of atoms in the 3D MOT, compared to a pure 2D MOT by a factor of 20. After MOT compression and polarization gradient cooling, atoms are optically pumped into a magnetically trappable hyperfine state F = -1> to be loaded into a quadrupole-Ioffe-configuration (QUIC) trap. We enhance this optical pumping process by up to 300% by using two laser beams. After rf evaporative cooling, a Bose-Einstein condensate (BEC) with more than 2 x 107 atoms is achieved.

  14. Temperature and number evolution of cold cesium atoms inside a glass cell

    Huang, J Q; Wang, S G; Wang, Z B; Wang, L J

    2015-01-01

    We report an experimental study on the temperature and number evolution of the cold cesium atoms diffusively cooled inside a wall-coated glass cell by measuring the absorption profile of the 62S1/2 (F=4)-62P3/2 (F'=5) transition line with a weak probe laser in the evolution process. We found that the temperature of the cold atoms first gradually decreases from 16 mK to 9 mK, and then rapidly increases. A theoretical model of the number evolution is built, which includes the temperature of the cold atoms and the fraction p of the cold cesium atoms elastically reflected by the cell wall. The theoretical model is consistent with the experimental result very well, and the fraction p is obtained to be (0.58 +/- 0.03), which reveals that the cold cesium atoms are not all heated to the ambient temperature by a single collision with the cell wall.

  15. K-LL Auger transition probabilities for elements with low and intermediate atomic numbers

    Chen, M. H.; Crasemann, B.

    1973-01-01

    Radiationless K-LL transition probabilities have been calculated nonrelativistically in j-j coupling and in intermediate coupling, without and with configuration interaction, for elements with atomic numbers from 13 to 47. The system is treated as a coupled two-hole configuration. The single-particle radial wave functions required in the calculation of radial matrix elements, and in the calculation of mixing coefficients in the intermediate-coupling scheme, were obtained from Green's atomic independent-particle model. Comparison with previous theoretical work and with experimental data is made. The effects of intermediate coupling, configuration interaction, and relativity are noted.

  16. Comparison of effective atomic numbers of the cancerous and normal kidney tissue

    The effective atomic number (Zeff) and electron density (Ne) of normal kidney and cancerous kidney have been computed for total and partial photon interactions by computing the molecular, atomic, and electronic cross section in the wide energy range of 1 keV-100 GeV using WinXCOM. The mean Zeff and Ne of normal kidney and cancerous kidney in the various energy ranges and for total and partial photon interactions are tabulated. The variation of effective Ne with energy is shown graphically for all photon interactions. In addition to this computer tomography (CT), numbers of normal kidney and cancerous kidney for photon interaction and energy absorption is also computed. The role of Zeff in the dual-energy dividing radiography is also discussed. The values of Zeff and Ne for cancerous kidney are higher than normal kidney. This is due to the levels of elements K, Ca, Fe, Ni, and Se are lower and those of the elements Ti, Co, Zn, As, and Cd are higher in the cancer tissue of kidney than those observed in the normal tissue. The soft tissue and cancerous tissue are very similar, but their atomic number differs. The cancerous tissue exhibits a higher Zeff than the normal tissue. This fact helps in the dual-energy dividing radiography which enables to improve the diagnosis of the kidney cancer. Hence, the computed values may be useful in the diagnosis of the kidney cancer. CT numbers for normal kidney are higher than cancerous kidney. (author)

  17. Crystallization of Supercooled Liquid Elements Induced by Superclusters Containing Magic Atom Numbers

    Robert F. Tournier

    2014-08-01

    Full Text Available A few experiments have detected icosahedral superclusters in undercooled liquids. These superclusters survive above the crystal melting temperature Tm because all their surface atoms have the same fusion heat as their core atoms, and are melted by liquid homogeneous and heterogeneous nucleation in their core, depending on superheating time and temperature. They act as heterogeneous growth nuclei of crystallized phase at a temperature Tc of the undercooled melt. They contribute to the critical barrier reduction, which becomes smaller than that of crystals containing the same atom number n. After strong superheating, the undercooling rate is still limited because the nucleation of 13-atom superclusters always reduces this barrier, and increases Tc above a homogeneous nucleation temperature equal to Tm/3 in liquid elements. After weak superheating, the most stable superclusters containing n = 13, 55, 147, 309 and 561 atoms survive or melt and determine Tc during undercooling, depending on n and sample volume. The experimental nucleation temperatures Tc of 32 liquid elements and the supercluster melting temperatures are predicted with sample volumes varying by 18 orders of magnitude. The classical Gibbs free energy change is used, adding an enthalpy saving related to the Laplace pressure change associated with supercluster formation, which is quantified for n = 13 and 55.

  18. Determination of total mass attenuation coefficients, effective atomic numbers and electron densities for different shielding materials

    Highlights: • The gamma shielding properties of eight shielding materials have been investigated. • We calculated the total mass attenuation coefficients by using WinXCom program. • The values of effective atomic number and electron density are also calculated. • All parameters depend on chemical content and the incident photon energy. • The Field castable Heat Resistant is the most effective shielding material. - Abstract: In this paper, the interaction of gamma rays with some shielding materials has been studied. The total mass attenuation coefficient (μt) for eight shielding materials has been calculated by using WinXCOM program in the energy range from 1 keV to 100 GeV. Also, the effective atomic number (Zeff) and the effective electron density (Neff) were calculated using the values of the total mass attenuation coefficient. The dependence of these parameters on the incident photon energy and the chemical composition has been examined

  19. Development of gridded ionization chamber for measuring atomic number of fission fragments

    In order to investigate the mechanism of asymmetric mass division in low energy fission of actinides, the detector for measuring an atomic number (Z) for fission fragments has been developed. Because the atomic number is closely related to energy losses of fragments, the gridded ionization chamber with divided anode is useful for this purpose. The detector was designed and optical conditions such as the distance and electric potential between electrodes were searched using alpha particles from 252Cf. The total energy and energy losses of fission fragments from 252Cf were measured under the obtained conditions. It was found that fission fragments lost most of the kinetic energy in the beginning of their range. This behavior agrees qualitatively with results of simulation by TRIM code. In the presentation, the results of energy measurements under various conditions will be shown and discussed. (author)

  20. Effective atomic number accuracy for kidney stone characterization using spectral CT

    Joshi, M.; Langan, D. A.; Sahani, D. S.; Kambadakone, A.; Aluri, S.; Procknow, K.; Wu, X.; Bhotika, R.; Okerlund, D.; Kulkarni, N.; Xu, D.

    2010-04-01

    The clinical application of Gemstone Spectral ImagingTM, a fast kV switching dual energy acquisition, is explored in the context of noninvasive kidney stone characterization. Utilizing projection-based material decomposition, effective atomic number and monochromatic images are generated for kidney stone characterization. Analytical and experimental measurements are reported and contrasted. Phantoms were constructed using stone specimens extracted from patients. This allowed for imaging of the different stone types under similar conditions. The stone specimens comprised of Uric Acid, Cystine, Struvite and Calcium-based compositions. Collectively, these stone types span an effective atomic number range of approximately 7 to 14. While Uric Acid and Calcium based stones are generally distinguishable in conventional CT, stone compositions like Cystine and Struvite are difficult to distinguish resulting in treatment uncertainty. Experimental phantom measurements, made under increasingly complex imaging conditions, illustrate the impact of various factors on measurement accuracy. Preliminary clinical studies are reported.

  1. Dynamical decoherence in a cavity with a large number of two-level atoms

    Frasca, M

    2004-01-01

    We consider a large number of two-level atoms interacting with the mode of a cavity in the rotating-wave approximation (Tavis-Cummings model). We apply the Holstein-Primakoff transformation to study the model in the limit of the number of two-level atoms, all in their ground state, becoming very large. The unitary evolution that we obtain in this approximation is applied to a macroscopic superposition state showing that, when the coherent states forming the superposition are enough distant, then the state collapses on a single coherent state describing a classical radiation mode. This appear as a true dynamical effect that could be observed in experiments with cavities.

  2. Some new developments in the field of high atomic number semiconductor materials

    A presentation of the main properties of high atomic number materials able to work as room temperature dectectors is made, including present status of synthesis. We summarize some applications in nuclear medical probe, tomography scanners, dosimetry and instrumentation. Mainly focused on CdTe and Hg I2 in monocrystal form the presentation will include some industrial applications. Hg I2 is also presented as a photodetector associated with scintillators

  3. Measurement of atom numbers of compound α source by using a gridded ionization chamber

    Atom numbers of the isotopes of a compound α source are measured by using a gridded ionization chamber (GIC). Make full use of the characteristics of the GIC, the self-absorption and scattering effects are corrected, and the precise results are derived. The study establishes the basis of the further experiment of the light nuclei (n, α) reaction. The method can also be used in measuring the weak α source. (authors)

  4. The effective atomic number for gamma ray interactions with heavy metal oxide glasses

    Manohara, S. R.; Hanagodimath, S.M.; Gerward, Leif

    2010-01-01

    The effective atomic number, Z(eff), and the effective electron density, N-el,N-eff, have been calculated at photon energies from 1 keV to 100 GeV for CaO-SrO-B2O3, ZnO-PbO-B2O3, and CdO-PbO-B2O3 glasses with potential applications as gamma ray shielding materials. Appreciable variations are note...

  5. Carbon nanotube scaffolds with controlled porosity as electromagnetic absorbing materials in the gigahertz range

    González, M.; Crespo, M.; Baselga, J.; Pozuelo, J.

    2016-05-01

    Control of the microscopic structure of CNT nanocomposites allows modulation of the electromagnetic shielding in the gigahertz range. The porosity of CNT scaffolds has been controlled by two freezing protocols and a subsequent lyophilization step: fast freezing in liquid nitrogen and slow freezing at -20 °C. Mercury porosimetry shows that slowly frozen specimens present a more open pore size (100-150 μm) with a narrow distribution whereas specimens frozen rapidly show a smaller pore size and a heterogeneous distribution. 3D-scaffolds containing 3, 4, 6 and 7% CNT were infiltrated with epoxy and specimens with 2, 5 and 8 mm thicknesses were characterized in the GHz range. Samples with the highest pore size and porosity presented the lowest reflected power (about 30%) and the highest absorbed power (about 70%), which allows considering them as electromagnetic radiation absorbing materials.Control of the microscopic structure of CNT nanocomposites allows modulation of the electromagnetic shielding in the gigahertz range. The porosity of CNT scaffolds has been controlled by two freezing protocols and a subsequent lyophilization step: fast freezing in liquid nitrogen and slow freezing at -20 °C. Mercury porosimetry shows that slowly frozen specimens present a more open pore size (100-150 μm) with a narrow distribution whereas specimens frozen rapidly show a smaller pore size and a heterogeneous distribution. 3D-scaffolds containing 3, 4, 6 and 7% CNT were infiltrated with epoxy and specimens with 2, 5 and 8 mm thicknesses were characterized in the GHz range. Samples with the highest pore size and porosity presented the lowest reflected power (about 30%) and the highest absorbed power (about 70%), which allows considering them as electromagnetic radiation absorbing materials. Electronic supplementary information (ESI) available: Scheme of hydrogenated derivative of diglycidyl ether of bisphenol-A (HDGEBA) and m-xylylenediamine; X-ray diffractograms of pristine CNT

  6. Improved atom number with a dual color magneto—optical trap

    We demonstrate a novel dual color magneto—optical trap (MOT), which uses two sets of overlapping laser beams to cool and trap 87Rb atoms. The volume of cold cloud in the dual color MOT is strongly dependent on the frequency difference of the laser beams and can be significantly larger than that in the normal MOT with single frequency MOT beams. Our experiment shows that the dual color MOT has the same loading rate as the normal MOT, but much longer loading time, leading to threefold increase in the number of trapped atoms. This indicates that the larger number is caused by reduced light induced loss. The dual color MOT is very useful in experiments where both high vacuum level and large atom number are required, such as single chamber quantum memory and Bose—Einstein condensation (BEC) experiments. Compared to the popular dark spontaneous-force optical trap (dark SPOT) technique, our approach is technically simpler and more suitable to low power laser systems. (rapid communication)

  7. Improved atom number with a dual color magneto-optical trap

    Cao Qiang; Luo Xin-Yu; Gao Kui-Yi; Wang Xiao-Rui; Chen Dong-Min; Wang Ru-Quan

    2012-01-01

    We demonstrate a novel dual color magneto-optical trap (MOT),which uses two sets of overlapping laser beams to cool and trap 87Rb atoms.The volume of cold cloud in the dual color MOT is strongly dependent on the frequency difference of the laser beams and can be significantly larger than that in the normal MOT with single frequency MOT beams.Our experiment shows that the dual color MOT has the same loading rate as the normal MOT,but much longer loading time,leading to threefold increase in the number of trapped atoms.This indicates that the larger number is caused by reduced light induced loss.The dual color MOT is very useful in experiments where both high vacuum level and large atom number are required,such as single chamber quantum memory and Bose Einstein condensation (BEC) experiments.Compared to the popular dark spontaneous-force optical trap (dark SPOT) technique,our approach is technically simpler and more suitable to low power laser systems.

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

    Shivalinge Gowda; S Krishnaveni; T Yashoda; T K Umesh; Ramakrishna Gowda

    2004-09-01

    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 energy in elements of atomic number 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.

  9. Quantitative imaging of electron density and effective atomic number using phase contrast CT

    Qi, Zhihua; Zambelli, Joseph; Bevins, Nicholas; Chen, Guang-Hong

    2010-05-01

    Compared to single energy CT, which only provides information for x-ray linear attenuation coefficients, dual-energy CT is able to obtain both the electron density and effective atomic number for different materials in a quantitative way. In this study, as an alternative to dual-energy CT, a novel quantitative imaging method based on phase contrast CT is presented. Rather than requiring two projection data sets with different x-ray energy spectra, diffraction-grating-based phase contrast CT is capable of reconstructing images of both linear attenuation and refractive index decrement from the same projection data using a single x-ray energy spectra. From the two images, quantitative information of both the electron density and effective atomic number can be extracted. Two physical phantoms were constructed and used to validate the presented method. Experimental results demonstrate that (1) electron density can be accurately determined from refractive index decrement through a linear relationship, and (2) the effective atomic number can be explicitly derived from the ratio of the linear attenuation to refractive index decrement using a power function plus a constant. The presented method will provide insight into the technique of material separation and find its use in medical and industrial applications.

  10. Quantitative imaging of electron density and effective atomic number using phase contrast CT

    Compared to single energy CT, which only provides information for x-ray linear attenuation coefficients, dual-energy CT is able to obtain both the electron density and effective atomic number for different materials in a quantitative way. In this study, as an alternative to dual-energy CT, a novel quantitative imaging method based on phase contrast CT is presented. Rather than requiring two projection data sets with different x-ray energy spectra, diffraction-grating-based phase contrast CT is capable of reconstructing images of both linear attenuation and refractive index decrement from the same projection data using a single x-ray energy spectra. From the two images, quantitative information of both the electron density and effective atomic number can be extracted. Two physical phantoms were constructed and used to validate the presented method. Experimental results demonstrate that (1) electron density can be accurately determined from refractive index decrement through a linear relationship, and (2) the effective atomic number can be explicitly derived from the ratio of the linear attenuation to refractive index decrement using a power function plus a constant. The presented method will provide insight into the technique of material separation and find its use in medical and industrial applications.

  11. Effective atomic number of dental smalt; Numero atomico efetivo do esmalte dentario

    Rodas D, J.E.; Nogueira, M.S. [Departamento de Fisica e Matematica da FFCLRP-USP. 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

    1998-12-31

    The effective atomic numbers Z are enough utilized for to characterize the interactions of ionizing radiation with matter. Particularly for the Z calculation in biological tissues and/or composed materials we need to know the relationship between the cross sections of the diverse radiations interactions with mattera and the atomic numbers Z of the constituent elements in the tissue or composed material. Normally the cross section by atom {sigma} {sup 2} is proportional to Z{sup m}. The m value depends of the iterative process type and the energy of the incident photons. In the case of the photoelectric interaction, the m vary will vary between 4,698 and 4,799 for energies between 10 to 200 keV. It was verified that constituent elements with high Z (>20) they had a major contribution. The m values for the Compton interation and the coherent scattering were calculated of similar way. Knowing the m values, we calculate the partials Z of a composed material. For the calculation of total Z, we can use alternatives starting from the equivalent atomic number corresponding to the total cross section {sigma} {sup d} tot, mc of the composed material. In this work for the calculation of Z values corresponding to diverse interations, we applied a linear regression at the values of Ln {sigma} {sup a} x LnZ for different energies. In general, to characterize a simulator material of a tissue or composed material we need to know the total Z in function of the photon energy applied to dental smalt increases until some hundreds of keV the partial values of Z owing to photoelectric effect and the coherent scattering this is owing to the smalt has a great concentration of elements with high Z. (Author)

  12. Comparison of silicon oxide and silicon carbide absorber materials in silicon thin-film solar cells

    Walder Cordula

    2015-01-01

    Full Text Available Since solar energy conversion by photovoltaics is most efficient for photon energies at the bandgap of the absorbing material the idea of combining absorber layers with different bandgaps in a multijunction cell has become popular. In silicon thin-film photovoltaics a multijunction stack with more than two subcells requires a high bandgap amorphous silicon alloy top cell absorber to achieve an optimal bandgap combination. We address the question whether amorphous silicon carbide (a-SiC:H or amorphous silicon oxide (a-SiO:H is more suited for this type of top cell absorber. Our single cell results show a better performance of amorphous silicon carbide with respect to fill factor and especially open circuit voltage at equivalent Tauc bandgaps. The microstructure factor of single layers indicates less void structure in amorphous silicon carbide than in amorphous silicon oxide. Yet photoconductivity of silicon oxide films seems to be higher which could be explained by the material being not truly intrinsic. On the other hand better cell performance of amorphous silicon carbide absorber layers might be connected to better hole transport in the cell.

  13. Comparison of silicon oxide and silicon carbide absorber materials in silicon thin-film solar cells

    Walder, Cordula; Kellermann, Martin; Wendler, Elke; Rensberg, Jura; von Maydell, Karsten; Agert, Carsten

    2015-02-01

    Since solar energy conversion by photovoltaics is most efficient for photon energies at the bandgap of the absorbing material the idea of combining absorber layers with different bandgaps in a multijunction cell has become popular. In silicon thin-film photovoltaics a multijunction stack with more than two subcells requires a high bandgap amorphous silicon alloy top cell absorber to achieve an optimal bandgap combination. We address the question whether amorphous silicon carbide (a-SiC:H) or amorphous silicon oxide (a-SiO:H) is more suited for this type of top cell absorber. Our single cell results show a better performance of amorphous silicon carbide with respect to fill factor and especially open circuit voltage at equivalent Tauc bandgaps. The microstructure factor of single layers indicates less void structure in amorphous silicon carbide than in amorphous silicon oxide. Yet photoconductivity of silicon oxide films seems to be higher which could be explained by the material being not truly intrinsic. On the other hand better cell performance of amorphous silicon carbide absorber layers might be connected to better hole transport in the cell.

  14. Inorganic-organic solar cells based on quaternary sulfide as absorber materials.

    Hong, Tiantian; Liu, Zhifeng; Yan, Weiguo; Liu, Junqi; Zhang, Xueqi

    2015-12-14

    We report a novel promising quaternary sulfide (CuAgInS) to serve as a semiconductor sensitizer material in the photoelectrochemical field. In this study, CuAgInS (CAIS) sulfide sensitized ZnO nanorods were fabricated on ITO substrates through a facile and low-cost hydrothermal chemical method and applied on photoanodes for solar cells for the first time. The component and stoichiometry were key factors in determining the photoelectric performance of CAIS sulfide, which were controlled by modulating their reaction time. ZnO/Cu0.7Ag0.3InS2 nanoarrays exhibit an enhanced optical and photoelectric performance and the power conversion efficiency of ITO/ZnO/Cu0.7Ag0.3InS2/P3HT/Pt solid-state solar cell was up to 1.80%. The remarkable performance stems from improved electron transfer, a higher efficiency of light-harvesting and appropriate band gap alignment at the interface of the ZnO/Cu0.7Ag0.3InS2 NTs. The research indicates that CAIS as an absorbing material has enormous potential in solar cell systems. PMID:26553746

  15. Producing of Impedance Tube for Measurement of Acoustic Absorption Coefficient of Some Sound Absorber Materials

    R. Golmohammadi

    2008-04-01

    Full Text Available Introduction & Objective: Noise is one of the most important harmful agents in work environment. In spit of industrial improvements, exposure with over permissible limit of noise is counted as one of the health complication of workers. In Iran, do not exact information of the absorption coefficient of acoustic materials. Iranian manufacturer have not laboratory for measured of sound absorbance of their products, therefore using of sound absorber is limited for noise control in industrial and non industrial constructions. The goal of this study was to design an impedance tube based on pressure method for measurement of the sound absorption coefficient of acoustic materials.Materials & Methods: In this study designing of measuring system and method of calculation of sound absorption based on a available equipment and relatively easy for measurement of the sound absorption coefficient related to ISO10534-1 was performed. Measuring system consist of heavy asbestos tube, a pure tone sound generator, calibrated sound level meter for measuring of some commonly of sound absorber materials was used. Results: In this study sound absorption coefficient of 23 types of available acoustic material in Iran was tested. Reliability of results by three repeat of measurement was tested. Results showed that the standard deviation of sound absorption coefficient of study materials was smaller than .Conclusion: The present study performed a necessary technology of designing and producing of impedance tube for determining of acoustical materials absorption coefficient in Iran.

  16. Results of the Workshop on Microwave-Absorbing Materials for Accelerators (MAMA): A Personal View

    Campisi, I E

    1993-04-01

    The first workshop on the properties and uses of special materials for absorption of microwaves in particle accelerators was held at the Continuous Electron Beam Accelerator Facility (CEBAF) in Newport News, February 22-24, 1993. The meeting's purpose was to review the advances of ceramic and materials science and to describe the accelerator projects the success of which strongly depends on the existence and availability of microwave-absorbing materials with special characteristics. Scientists from various branches of physics, materials science, microwave engineering, accelerator physics and from national and international laboratories, from universities and industries participated in this gathering. This interdisciplinary meeting brought new people and new ideas together which in the future will bloom into better understanding of general materials and of physical processes and eventually to collaborative efforts to design and produce custom made materials. This paper describes the major topics covered in the workshop and is a personal elaboration of the author on the future possibilities opened by this interaction.

  17. Gamma attenuation characteristics and effective atomic numbers of polypropylene and polystyrene

    Gamma attenuation characteristics of polymer materials polypropylene and polystyrene are studied along with lead, iron and aluminum by subjecting them to gamma ray fields of known energies. A precise method for determination of mass attenuation coefficient of gamma rays using NaI (Tl) detector with 8k MCA is described in this paper. In order to minimize the effect of multiple scattering on the mass attenuation coefficient (μ/ρ) value, a good geometry arrangement was setup. For standardization purposes the mass attenuation coefficients of elemental shields like lead, iron and aluminum were measured and then, this method is applied for polymers of interest. The total atomic cross-section (σt,a) and total electronic cross-section (σt,el) were determined and by knowing the values of (σt,a) and (σt,el) the effective atomic numbers were estimated using the NIST XCOM. The experimental values were compared with the theoretical values. The agreement of experimental values of mass attenuation coefficients and effective atomic numbers with the theory has been found to be quite satisfactory. (author)

  18. Study of the mass attenuation coefficients and effective atomic numbers in some gemstones

    The total mass attenuation coefficients for natural beryl, corundum, garnet, pearl, and tourmaline gemstones were measured at 81, 356.5, 661.6, 1173.2, and 1332.5 keV photon energies. The samples were irradiated with 133Ba, 137Cs and 60Co radioactive point sources using gamma ray transmission method. Total atomic and electronic cross-sections, effective atomic numbers and electron densities were determined experimentally and theoretically. The experimental values were compared with the calculated values for all samples. The calculations were extended for total photon interactions in a wide energy range (1 keV-100 GeV) using WinXCom program of the most commonly irradiated gemstones with different sources of ionized radiation. The values of these parameters have been found to vary with photon energy and chemical composition of the gemstones. All variations of these parameters against energy are shown graphically for total photon interactions. (author)

  19. Measurement of atomic number and mass attenuation coefficient in magnesium ferrite

    R H Kadam; S T Alone; G K Bichile; K M Jadhav

    2007-05-01

    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 (), mass attenuation coefficient (/ρ), total atomic cross-section (tot), total electronic cross-section (ele) and the effective atomic number (eff) were calculated for pure magnesium ferrite (MgFe2O4). The values of -ray mass attenuation coefficient were obtained using a NaI energy selective scintillation counter with radioactive -ray sources having energy 0.36, 0.511, 0.662, 1.17 and 1.28 MeV. The experimentally obtained values of /ρ and eff agreed fairly well with those obtained theoretically.

  20. Measurements of mass attenuation coefficient, effective atomic number and electron density of some amino acids

    The mass attenuation coefficients of some amino acids, such as DL-aspartic acid-LR(C4H7NO4), L-glutamine (C4H10N2O3), creatine monohydrate LR(C4H9N3O2H2O), creatinine hydrochloride (C4H7N3O·HCl) L-asparagine monohydrate(C4H9N3O2H2O), L-methionine LR(C5H11NO2S), were measured at 122, 356, 511, 662, 1170, 1275 and 1330 keV photon energies using a well-collimated narrow beam good geometry set-up. The gamma-rays were detected using NaI (Tl) scintillation detection system with a resolution of 0.101785 at 662 keV. The attenuation coefficient data were then used to obtain the effective atomic numbers (Zeff), and effective electron densities (Neff) of amino acids. It was observed that the effective atomic number (Zeff) and effective electron densities (Neff) initially decrease and tend to be almost constant as a function of gamma-ray energy. Zeff and Neff experimental values showed good agreement with the theoretical values with less than 1% error for amino acids. - Highlights: • We report the values of mass attenuation coefficients (μ/ρ). • The values of (Zeff) i.e. effective atomic number are calculated. • Measurement of effective electron density (Neff) of some amino acids. • Comparison of all μ/ρ values with XCOM programme

  1. Study on Material Discrimination by Atomic Number Using Dual Energy γ-Rays

    This study aims to demonstrate the practical value of radioscopic differentiation of materials. The dual energy method is proposed for identifying materials according to atomic numbers. The differentiation of materials is achieved by comparing the attenuation ratio of low and high energy photons. We used gamma-rays of 0.662 MeV and 1.25 MeV and NaI(Tl) scintillation detector with a Multi-channel Analyzer (MCA). We also carried out the Monte Carlo simulation for the case of bremsstrahlung radiation from dual electron beams of 4 MeV and 9 MeV

  2. Efficiency of ablative plasma energy transfer into a massive aluminum target using different atomic number ablators

    Kasperczuk, A.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Stepniewski, W.; Jach, K.; Swierczynski, R.; Renner, Oldřich; Šmíd, Michal; Ullschmied, Jiří; Cikhart, J.; Klír, D.; Kubeš, P.; Řezáč, K.; Krouský, Eduard; Pfeifer, Miroslav; Skála, Jiří

    2015-01-01

    Roč. 33, č. 3 (2015), s. 379-386. ISSN 0263-0346 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk(CZ) LD14089 EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Grant ostatní: ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; AVČR(CZ) M100101208 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : ablator atomic number * crater volume * laser energy transfer * plasma ablative pressure Subject RIV: BL - Plasma and Gas Discharge Physics; BH - Optics, Masers, Lasers (UFP-V) Impact factor: 1.295, year: 2014

  3. Evolution of the superposition of displaced number states with the two-atom multiphoton Jaynes Cummings model: interference and entanglement

    El-Orany, Faisal A. A.

    2006-11-01

    In this paper, we study the evolution of two two-level atoms interacting with a single-mode quantized radiation field, namely, the two-atom multiphoton Jaynes-Cummings model (JCM). We assume that the field and the atoms are initially prepared in the superposition of displaced number states and excited atomic states, respectively. For this system, we investigate the atomic inversion, Wigner function, phase distribution and entanglement. We show that for symmetric (asymmetric) atoms, the system can generate asymmetric (symmetric) cat states at a quarter of the revival time. Furthermore, the degrees of entanglement for the field-atoms and the one-atom-remainder tangles depend on the rate of energy flow between the parties. The interference in phase space decreases the degree of entanglement in the bipartite.

  4. Determination of the effective atomic and mass numbers for mixture and compound materials in high energy photon interactions

    In consideration the radiological properties of materials and studying the scattering processes in atomic and nuclear physics, the effective atomic and mass numbers is widely employed. These numbers have been calculated for any mixed or composite materials in interaction with high energy photons (Linac in radiation therapy). A pair equation in terms of these numbers is obtained. The first equation has been derived from the conservation of mass energy law and the second by minimizing the binding energy from the semiempirical mass formula (Myers and Swiatecki formula) that gives a relation between atomic and mass numbers for stable nuclei approximately. By these equations one can obtain the effective atomic and mass numbers for any compound or mixed materials uniquely. These numbers are calculated for some materials and compared with the other studies. (author)

  5. Calculation of radiation attenuation coefficients, effective atomic numbers and electron densities for some building materials

    Some building materials, regularly used in Turkey, such as sand, cement, gas concrete (lightweight, aerated concrete), tile and brick, have been investigated in terms of mass attenuation coefficient, effective atomic, numbers (Zeff), effective electron densities (Ne) and photon interaction cross section (σa) at 14 different energies from 81- to 1332-keV gamma-ray energies. The gamma rays were detected by using gamma-ray spectroscopy, a High Purity Germanium (HPGe) detector. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence spectrometer. Mass attenuation coefficients of these samples have been compared with tabulations based upon the results of WinXcom. The theoretical mass attenuation coefficients were estimated using the mixture rule and the experimental values of investigated parameters were compared with the calculated values. The agreement of measured values of mass attenuation coefficient, effective atomic numbers, effective electron densities and photon interaction cross section with the theory has been found to be quite satisfactory. (authors)

  6. Measurements of mass attenuation coefficient, effective atomic number and electron density of some amino acids

    Kore, Prashant S.; Pawar, Pravina P.

    2014-05-01

    The mass attenuation coefficients of some amino acids, such as DL-aspartic acid-LR(C4H7NO4), L-glutamine (C4H10N2O3), creatine monohydrate LR(C4H9N3O2H2O), creatinine hydrochloride (C4H7N3O·HCl) L-asparagine monohydrate(C4H9N3O2H2O), L-methionine LR(C5H11NO2S), were measured at 122, 356, 511, 662, 1170, 1275 and 1330 keV photon energies using a well-collimated narrow beam good geometry set-up. The gamma-rays were detected using NaI (Tl) scintillation detection system with a resolution of 0.101785 at 662 keV. The attenuation coefficient data were then used to obtain the effective atomic numbers (Zeff), and effective electron densities (Neff) of amino acids. It was observed that the effective atomic number (Zeff) and effective electron densities (Neff) initially decrease and tend to be almost constant as a function of gamma-ray energy. Zeff and Neff experimental values showed good agreement with the theoretical values with less than 1% error for amino acids.

  7. Calculation of radiation attenuation coefficients, effective atomic numbers and electron densities for some building materials.

    Damla, N; Baltas, H; Celik, A; Kiris, E; Cevik, U

    2012-07-01

    Some building materials, regularly used in Turkey, such as sand, cement, gas concrete (lightweight, aerated concrete), tile and brick, have been investigated in terms of mass attenuation coefficient (μ/ρ), effective atomic, numbers (Z(eff)), effective electron densities (N(e)) and photon interaction cross section (σ(a)) at 14 different energies from 81- to 1332-keV gamma-ray energies. The gamma rays were detected by using gamma-ray spectroscopy, a High Purity Germanium (HPGe) detector. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence spectrometer. Mass attenuation coefficients of these samples have been compared with tabulations based upon the results of WinXcom. The theoretical mass attenuation coefficients were estimated using the mixture rule and the experimental values of investigated parameters were compared with the calculated values. The agreement of measured values of mass attenuation coefficient, effective atomic numbers, effective electron densities and photon interaction cross section with the theory has been found to be quite satisfactory. PMID:22128356

  8. Estimation of effective atomic number in the Rayleigh to Compton scattering ratio using different methods

    Kurudirek, M.; Büyükyıldız, M.

    2016-06-01

    The Rayleigh to Compton scattering ratio (R/C) is a very convenient parameter, which can be utilized in material analysis and estimating effective atomic number (Zeff). In the case for a relatively low scattering angle, for which the energy of the Compton scattered photons is not very much different from that of incident photons, the corrections due to self-absorption for Rayleigh and Compton scattering will be roughly equal. Therefore, it enables a result to be obtained which is almost independent of X-ray attenuation inside the sample and it will depend only on the material under investigation. The most frequently used method for calculation of Zeff available in literature is plotting R/C of elements as a function of atomic number and constituting the best fit curve. From this fit curve, the respective Zeff can be determined using R/C of the material. In the present study, we report Zeff of different materials using different methods such as interpolation and direct methods as possible alternatives to the most common fitting method. The results were compared with the experiments wherever possible. The agreement between interpolation method and the fitting method was found to be very satisfactory as relative changes (%) were always less than 9% while the direct method results with somehow significantly higher values of Zeff when compared to the other methods.

  9. Critical radius and critical number of gas atoms for cavities containing a Van der Waals gas

    The effect of gas on void nucleation and growth is particularly important for structural materials in fusion reactors because of the high production of helium by neutron-induced transmutation reactions. Gas reduces the critical radius for bias driven growth and there is a critical number of gas atoms, n/sub g/*, at which the critical radius is reduced essentially to zero. The significance of this is that the time interval to the accumulation of n/sub g/* gas atoms may determine the time to the onset of bias driven swelling where n/sub g/* is large. In previous papers these critical quantities were given for an ideal gas. Recently, we presented the results for a Van der Waals gas. Here the derivation of these relations is presented and further results of calculations are given. At low temperatures (high pressures) the results depart from those of the ideal gas, with the critical number affected more strongly than the critical radius. Comparisons are made with earlier calculations

  10. The influence of basic composition and microstructures on the properties of Ni–Zn ferrite radio-absorbing materials

    This work deals with the research into the electromagnetic properties of Ni–Zn ferrite radio-absorbing materials obtained by the ceramic method under different technological conditions. There has been ascertained the influence of basic composition and microstructures on the level of absorption of electromagnetic radiation by Ni–Zn ferrite radio-absorbing materials. The results indicate that increasing the surplus Fe2O3 up to 51.0 mol% leads to a shift in frequency interval in the direction of low frequencies. It can be explained by increase of the permeability and permittivity of a ferrite. - Highlights: • Increasing Fe2O3 up to 51.0 mol% leads to increasing permeability of a ferrite. • It also leads to a shift in frequency interval in the direction of low frequencies. • It is more effective to introduce Fe2O3 at the second stage of the crushing

  11. Dependence of microwave absorption properties on ferrite volume fraction in MnZn ferrite/rubber radar absorbing materials

    Gama, Adriana M.; Mirabel C. Rezende; Dantas, Christine C.

    2011-01-01

    We report the analysis of measurements of the complex magnetic permeability ($\\mu_r$) and dielectric permittivity ($\\epsilon_r$) spectra of a rubber radar absorbing material (RAM) with various MnZn ferrite volume fractions. The transmission/reflection measurements were carried out in a vector network analyzer. Optimum conditions for the maximum microwave absorption were determined by substituting the complex permeability and permittivity in the impedance matching equation. Both the MnZn ferri...

  12. Characterization & Modification of Copper and Iron Oxide Nanoparticles for Application as Absorber Material in Silicon based Thin Film Solar Cells

    Nuys, Maurice

    2015-01-01

    The present thesis deals with the characterization and modification of semiconducting copper oxide (CuO, Cu2O) and iron oxide (gamma-Fe2O3, alpha-Fe2O3) nanoparticles, which provide a basis for an innovative solar cell concept involving nanoparticles composed of almost unlimitedly available elements as absorber material in thin film solar cells. This approach is promising to meet the requirements of increasing the production capacity and lowering the production costs if the nanoparticles exhi...

  13. Effective atomic number, electron density and kerma of gamma radiation for oxides of lanthanides

    R S Niranjan; B Rudraswamy; N Dhananjaya

    2012-03-01

    An attempt has been made to estimate the effective atomic number, electron density (0.001 to 105 MeV) and kerma (0.001 to 20 MeV) of gamma radiation for a wide range of oxides of lanthanides using mass attenuation coefficient from WinXCom and mass energy absorption coefficient from Hubbell and Seltzer. The values of these parameters have been found to change with energy for different oxides of lanthanides. The lanthanide oxides find remarkable applications in the field of medicine, biology, nuclear engineering and space technology. Nano-oxides of lanthanide find applications in display and lighting industry.

  14. Study of Effective Atomic Number in Compounds Using Gamma-Ray Interaction

    Rudraswamy, B.; Dhananjaya, N.

    2009-03-01

    In view of low cost, hydrogenous materials such as Polyethylene and CH2 have been developed and being used currently by NASA as an effective galactic cosmic radiation shields in place of aluminum for hull design of spacecraft. Lead, steel and concrete which are currently being used as effective radiation shields for the treatment of rooms equipped with Electron accelerators are found be quite expensive. Hence, it is necessary to use alternative low cost material which serves as an effective radiation shield. In the present study, an attempt has been made to measure gamma-ray mass attenuation coefficient, effective atomic number and absorbed dose rate of the compounds such as NH4Cl, KCl, and CdO using various gamma sources of energies 356, 511, 662, 1173, and 1332 keV. These parameters are expected to gives vital information on the selection of shielding materials.

  15. Study of effective atomic number of breast tissues determined using the elastic to inelastic scattering ratio

    Antoniassi, M.; Conceicao, A.L.C. [Departamento de Fisica e Matematica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil); Poletti, M.E., E-mail: poletti@ffclrp.usp.br [Departamento de Fisica e Matematica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil)

    2011-10-01

    In this work we have measured Compton and Rayleigh scattering radiation from normal (adipose and fibroglandular), benign (fibroadenoma) and malignant (ductal carcinoma) breast tissues using a monoenergetic beam of 17.44 keV and a scattering angle of 90{sup o} (x=0.99 A{sup -1}). A practical method using the area of Rayleigh and Compton scattering was used for determining the effective atomic number (Z{sub eff}) of the samples, being validated through measurements of several reference materials. The results show that there are differences in the distributions of Z{sub eff} of breast tissues, which are mainly related to the elemental composition of carbon (Z=6) and oxygen (Z=8) of each tissue type. The results suggest that is possible to use the method to characterize the breast tissues permitting study histological features of the breast tissues related to their elemental composition.

  16. Study of effective atomic number of breast tissues determined using the elastic to inelastic scattering ratio

    In this work we have measured Compton and Rayleigh scattering radiation from normal (adipose and fibroglandular), benign (fibroadenoma) and malignant (ductal carcinoma) breast tissues using a monoenergetic beam of 17.44 keV and a scattering angle of 90o (x=0.99 A-1). A practical method using the area of Rayleigh and Compton scattering was used for determining the effective atomic number (Zeff) of the samples, being validated through measurements of several reference materials. The results show that there are differences in the distributions of Zeff of breast tissues, which are mainly related to the elemental composition of carbon (Z=6) and oxygen (Z=8) of each tissue type. The results suggest that is possible to use the method to characterize the breast tissues permitting study histological features of the breast tissues related to their elemental composition.

  17. Negative differential resistance in a one-dimensional molecular wire with odd number of atoms

    S Lakshmi; Swapan K Pati

    2005-10-01

    We have investigated the effects of electron{phonon coupling on the current-voltage characteristics of a one-dimensional molecular wire with odd number of atoms. The wire has been modelled using the Su-Schreiffer-Heeger (SSH) Hamiltonian and the current{voltage characteristics have been obtained using the Landauer's formalism. In the presence of strong electron-lattice coupling, we find that there are regions of negative differential resistance (NDR) at some critical bias, due to the degeneracy in the energies of the frontier molecular orbitals. The presence of the applied bias and the electron{lattice coupling results in the delocalization of these low-lying molecular states leading to the NDR behaviour.

  18. Assessment of methods for estimation of effective atomic numbers of common human organ and tissue substitutes: waxes, plastics and polymers

    We calculated mass attenuation coefficients, effective atomic numbers and Kerma relative to air for human organ and tissue substitutes (i.e. wax, plastic and polymer materials). The effective atomic numbers of the tissue substitutes were calculated by the direct method, interpolation method, Auto-Zeff software and single value XMuDat program and then compared. The calculated effective atomic numbers were also compared with available experimental data and a good agreement was observed. A large difference in effective atomic numbers calculated by the direct and interpolation methods was observed in photoelectric and pair-production regions. The direct method was found to be appropriate for effective atomic number computation in low-(>10 keV) and medium-(0.1 ≤ E ≤ 10 MeV) photon energy regions. Kerma relative to air of the selected tissue substitutes was found to be dependent upon the atomic number and element compositions, which show a sharp peak due to K-edge absorption. (authors)

  19. Mass Attenuation Coefficients and Effective Atomic Numbers of Thermoluminescent Aluminum Oxide Based Glasses

    The photon mass attenuation coefficient of a newly prepared 15Al2O3-35P2O5- xCaO-(50-x)Na2CO3 glass system (symbolized as APCN), where x=5, 10, 15, 20, 25, 30, 35, 40 all in mol%, have been calculated at photon energies of 0.662 MeV (137Cs source) and 1.25 MeV (60Co source). In addition, the photon mass attenuation coefficient of 15Al2O3-35P2O5-25CaO-25Na2CO3 glass system (symbolized as APCN25-25), all in mol%, doped with different concentrations of SiO2 have been calculated. The WinXCOM software program on the basis of mixture rule was utilized in calculations. The total atomic (σt) and electronic (σe) cross sections, effective atomic number (Zeff) and electron density (Nel) were calculated. The results showed that the total mass attenuation coefficient showed an extremely dependence on incoherent scattering processes where it varies with Na2CO3 contents in the APCN composition while changing the concentrations of SiO2 in APCN25-25 glass showed slight changes in the values. Otherwise, the mass attenuation coefficient (µm) had higher values at 0.662 MeV than those of 1.25 MeV in both APCN and APCN25-25 glass systems. The values of Zeff showed a decrease with increasing Na2CO3 contents in the APCN composition. The should highly be considered in dealing with such prepared APCN glass system as a gamma ray detector, specially as thermoluminescence dosimeter.

  20. Absolute number densities of helium metastable atoms determined by atomic absorption spectroscopy in helium plasma-based discharges used as ambient desorption/ionization sources for mass spectrometry

    The absolute number densities of helium atoms in the 2s 3S1 metastable state were determined in four plasma-based ambient desorption/ionization sources by atomic absorption spectroscopy. The plasmas included a high-frequency dielectric barrier discharge (HF-DBD), a low temperature plasma (LTP), and two atmospheric-pressure glow discharges, one with AC excitation and the other with DC excitation. Peak densities in the luminous plumes downstream from the discharge capillaries of the HF-DBD and the LTP were 1.39 × 1012 cm−3 and 0.011 × 1012 cm−3, respectively. Neither glow discharge produced a visible afterglow, and no metastable atoms were detected downstream from the capillary exits. However, densities of 0.58 × 1012 cm−3 and 0.97 × 1012 cm−3 were measured in the interelectrode regions of the AC and DC glow discharges, respectively. Time-resolved measurements of metastable atom densities revealed significant random variations in the timing of pulsed absorption signals with respect to the voltage waveforms applied to the discharges. - Highlights: • We determine He metastable number densities for four plasma types • The highest number densities were observed in a dielectric barrier discharge • No helium metastable atoms were observed downstream from the exits of glow discharges

  1. Semiempirical fine-tuning for Hartree–Fock ionization potentials of atomic ions with non-integral atomic number

    Amovilli and March (2006) [8] used diffusion quantum Monte Carlo techniques to calculate the non-relativistic ionization potential I(Z) in He-like atomic ions for the range of (fractional) nuclear charges Z lying between the known critical value Zc=0.911 at which I(Z) tends to zero and Z=2. They showed that it is possible to fit I(Z) to a simple quadratic expression. Following that idea, we present here a semiempirical fine-tuning of Hartree–Fock ionization potentials for the isoelectronic series of He, Be, Ne, Mg and Ar-like atomic ions that leads to excellent estimations of Zc for these series. The empirical information involved is experimental ionization and electron affinity data. It is clearly demonstrated that Hartree–Fock theory provides an excellent starting point for determining I(Z) for these series

  2. Effects of atomic number Z on the energy distribution of hot electrons generated by femtosecond laser interaction with metallic targets

    Cai Da-Feng; Gu Yu-Qiu; Zheng Zhi-Jian; Zhou Wei-Min; Jiao Chun-Ye; Chen Hao; Wen Tian-Shu; Chunyu Shu-Tai

    2006-01-01

    The effects of atomic number Z on the energy distribution of hot electrons generated by the interaction of 60fs,130m J, 800nm, and 7×1017W/cm2 laser pulses with metallic targets have been studied experimentally. The results show that the number and the effective temperature of hot electrons increase with the atomic number Z of metallic targets, and the temperature of hot electrons are in the range of 190-230keV, which is consistent with a scaling law of hot electrons temperature.

  3. Mass attenuation coefficients, effective atomic numbers and effective electron densities for some polymers

    In this study, the total mass attenuation coefficients (mm) for some homo- and hetero-chain polymers, namely polyamide-6 (PA-6), poly-methyl methacrylate (PMMA), low-density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS) were measured at 59.5, 511, 661.6, 1173.2, 1274.5 and 1332.5 keV photon energies. The samples were separately irradiated with 241Am, 22Na, 137Cs and 60Co (638 kBq) radioactive gamma sources. The measurements were made by performing transmission experiments with a '2 x 2' NaI(Tl) scintillation detector having an energy resolution of 7 % at 662 keV gamma ray from the decay of 137Cs. The effective atomic numbers (Zeff) and the effective electron densities (Neff) were determined experimentally and theoretically using the obtained μm values for the investigated samples. Furthermore, Zeff and Neff of each polymer were computed for total photon interaction cross-sections using theoretical data over a wide energy region from 1 keV to 10 MeV. The experimental values of the selected polymers were found to be in good agreement with the theoretical values. (authors)

  4. Mass attenuation coefficients, effective atomic numbers and effective electron densities for some polymers.

    Kucuk, Nil; Cakir, Merve; Isitman, Nihat Ali

    2013-01-01

    In this study, the total mass attenuation coefficients (μ(m)) for some homo- and hetero-chain polymers, namely polyamide-6 (PA-6), poly-methyl methacrylate (PMMA), low-density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS) were measured at 59.5, 511, 661.6, 1173.2, 1274.5 and 1332.5 keV photon energies. The samples were separately irradiated with (241)Am, (22)Na, (137)Cs and (60)Co (638 kBq) radioactive gamma sources. The measurements were made by performing transmission experiments with a 2″×2″ NaI(Tl) scintillation detector having an energy resolution of 7 % at 662 keV gamma ray from the decay of (137)Cs. The effective atomic numbers (Z(eff)) and the effective electron densities (N(eff)) were determined experimentally and theoretically using the obtained μ(m) values for the investigated samples. Furthermore, Z(eff) and N(eff) of each polymer were computed for total photon interaction cross-sections using theoretical data over a wide energy region from 1 keV to 10 MeV. The experimental values of the selected polymers were found to be in good agreement with the theoretical values. PMID:22645382

  5. Interpolation of gamma-ray buildup factors in atomic number, using the geometrical progression (G-P) parameters

    The values of buildup factors for specified energy above K-edges and penetration distance vary smoothly with respect to atomic number, and the geometrical progression (G-P) parameters behave also similarly. An interpolation of buildup factors for an arbitrary elemental material was examined using the G-P parameters for an equivalent atomic number, where the G-P parameters are data fitted to the proposed American National Standard buildup factor data compilation of 17 elements from Be to Mo calculated by the moments method and those for 8 elements of Fe, Mo, Sn, La, Gd, W, Pb and U, including bremsstrahlung and fluorescence, calculated by the PALLAS code. It has been confirmed through various tests over a wide range of atomic number that the values of the buildup factors generated by interpolated G-P parameters can accurately reproduce the basic data calculated directly over the full range of energy within a few percent. The values of equivalent atomic number for mixture materials, such as water, air, concrete and lead glass of the density 4.36, are determined from a ratio of scattering cross section to the total attenuation coefficient. The buildup factors for these materials calculated using the G-P parameters, interpolated by the equivalent atomic number, are in good agreement with the basic data, except the buildup factors for lead glass to γ-ray energy above 3 MeV. (author)

  6. Determination of mass attenuation coefficients and effective atomic numbers for Inconel 738 alloy for different energies obtained from Compton scattering

    Highlights: ► Mass attenuation coefficient of Inconel 738 superalloy was measured. ► Gamma-ray energies were changed by Compton scattering technique. ► Effective atomic number and electron density are also calculated. ► All parameters decrease with increased energy. ► The experimental values are in good agreement with theoretical ones. - Abstract: The mass attenuation coefficient of Inconel 738 superalloy has been measured at different gamma ray energies by using the Compton scattering technique. The theoretical values of mass attenuation coefficient of a glass sample were calculated using WinXCom program. The effective atomic number and electron density are also calculated. The results showed that the mass attenuation coefficients, effective atomic number and electron density increase with the decrease in gamma ray energies which is in good agreement with theoretical values (less than 2% error)

  7. Revision of single atom local density and capture number varying with coverage in uniform depletion approximation and its effect on coalescence and number of stable clusters

    Shao Qing-Yi; Zhang Juan

    2011-01-01

    In vapour deposition,single atoms(adatoms)on the substrate surface are the main source of growth.The change in its density plays a decisive role in the growth of thin films and quantum size islands.In the nucleation and cluster coalescence stages of vapour deposition,the growth of stable clusters occurs on the substrate surface covered by stable clusters.Nucleation occurs in the non-covered part,while the total area covered by stable clusters on the substrate surface will gradually increase.Carefully taking into account the coverage effect,a revised single atom density rate equation is given for the famous and widely used thin-film rate equation theory,but the work of solving the revised equation has not been done.In this paper,we solve the equation and obtain the single-atom density and capture number by using a uniform depletion approximation.We determine that the single atom density is much lower than that evaluated from the single atom density rate equation in the traditional rate equation theory when the stable cluster coverage fraction is large,and it goes down very fast with an increase in the coverage fraction.The revised equation gives a higher value for the 'average' capture number than the present equation. It also increases with increasing coverage.That makes the preparation of single crystalline thin film materials difficult and the size control of quantum size islands complicated.We also discuss the effect of the revision on coalescence and the number of stable clusters in vapour deposition.

  8. An Estimation of the Number and Size of Atoms in a Printed Period

    Schaefer, Beth; Collett, Edward; Tabor-Morris, Anne; Croman, Joseph

    2011-01-01

    Elementary school students learn that atoms are very, very small. Students are also taught that atoms (and molecules) are the fundamental constituents of the material world. Numerical values of their size are often given, but, nevertheless, it is difficult to imagine their size relative to one's everyday surroundings. In order for students to…

  9. The influence of basic composition and microstructures on the properties of Ni–Zn ferrite radio-absorbing materials

    Andreev, V.G., E-mail: ilem58@mail.ru; Menshova, S.B.; Klimov, A.N.; Vergazov, R.M.

    2015-11-01

    This work deals with the research into the electromagnetic properties of Ni–Zn ferrite radio-absorbing materials obtained by the ceramic method under different technological conditions. There has been ascertained the influence of basic composition and microstructures on the level of absorption of electromagnetic radiation by Ni–Zn ferrite radio-absorbing materials. The results indicate that increasing the surplus Fe{sub 2}O{sub 3} up to 51.0 mol% leads to a shift in frequency interval in the direction of low frequencies. It can be explained by increase of the permeability and permittivity of a ferrite. - Highlights: • Increasing Fe{sub 2}O{sub 3} up to 51.0 mol% leads to increasing permeability of a ferrite. • It also leads to a shift in frequency interval in the direction of low frequencies. • It is more effective to introduce Fe{sub 2}O{sub 3} at the second stage of the crushing.

  10. Standard specification for boron-Based neutron absorbing material systems for use in nuclear spent fuel storage racks

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This specification defines criteria for boron-based neutron absorbing material systems used in racks in a pool environment for storage of nuclear light water reactor (LWR) spent-fuel assemblies or disassembled components to maintain sub-criticality in the storage rack system. 1.2 Boron-based neutron absorbing material systems normally consist of metallic boron or a chemical compound containing boron (for example, boron carbide, B4C) supported by a matrix of aluminum, steel, or other materials. 1.3 In a boron-based absorber, neutron absorption occurs primarily by the boron-10 isotope that is present in natural boron to the extent of 18.3 ± 0.2 % by weight (depending upon the geological origin of the boron). Boron, enriched in boron-10 could also be used. 1.4 The materials systems described herein shall be functional – that is always be capable to maintain a B10 areal density such that subcriticality Keff <0.95 or Keff <0.98 or Keff < 1.0 depending on the design specification for the service...

  11. Atoms

    刘洪毓

    2007-01-01

    Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what

  12. Chemical composition of human enamel and dentin. Preliminary results to determination of the effective atomic number

    The theoretical or practical dosimetry involving radiation interactions in humans needs the reliable elemental composition data of body tissues. The object of this research was to obtain the characterization dental hard tissues and to determine its effective atomic number. An analytical research of inorganic composition, from 30 intact human molars, extracted for periodontal reasons, was performed by Neutron Activation Analysis (NAA), ICP/AES, Thermogravimetric (TG) and Differential Thermal Analysis (DTA). The coronal dentin and enamel were separated by two techniques: (1) - mechanically by chipping and breaking by chirurgic hammer, allowed to dry in an electric oven for 5 hours at 160oC. (2) - through by high-running round steel burs. The samples were thoroughly cleaned with distilled deionizer water and sent for analysis in CDTN/CNEN laboratories, Belo Horizonte, Minas Gerais, Brazil. The results showed concentrations of 11 elements measured in dentin and enamel. The five elements of the higher concentration by neutron activation analysis and ICP/AES were Ca, P, Na, Mg and Al. Thermogravimetric analysis of enamel showed a loss of water of hydroxyapatite to 500oC. Thermogravimetric analyses of dentin showed tree temperatures at which mass loss occur. These processes are related to superficial water loss (100oC); organic decomposition and water liberation from hydroxyapaptite (100oC to 600oC); and the beginning of hydroxyapatite decomposition (600oC to 850oC). Differences, in mineral concentration, were found between enamel and dentin, with higher concentrations in enamel. The two techniques proposed to separate dentin and enamel, did not present differences in elements concentration, statement that the high-running round steel burs technique didn't affect the samples. (author)

  13. Atoms

    Completed by recent contributions on various topics (atoms and the Brownian motion, the career of Jean Perrin, the evolution of atomic physics since Jean Perrin, relationship between scientific atomism and philosophical atomism), this book is a reprint of a book published at the beginning of the twentieth century in which the author addressed the relationship between atomic theory and chemistry (molecules, atoms, the Avogadro hypothesis, molecule structures, solutes, upper limits of molecular quantities), molecular agitation (molecule velocity, molecule rotation or vibration, molecular free range), the Brownian motion and emulsions (history and general features, statistical equilibrium of emulsions), the laws of the Brownian motion (Einstein's theory, experimental control), fluctuations (the theory of Smoluchowski), light and quanta (black body, extension of quantum theory), the electricity atom, the atom genesis and destruction (transmutations, atom counting)

  14. Studying on preparation of super water absorbing materials by radiation modification techniques using bentonite and water soluble monomer

    Research on preparing water super absorbent materials using Di Linh bentonite and water soluble acrylic monomer has been carried out by gamma radiation grafting and crosslinking techniques. The research results showed that gel formed depends on the absorbed dose and the concentration of bentonite used, and not affected by the cleanliness of them. In the dose range studied, water swelling content reached 579 g.g-1 with swelling rate of 20 g.g-1.min-1, in salting solution water absorption capacity decreased very much in particular at high concentrations. In salting media, the water absorption capacity of studied product depends on the type of salt in order as follows NaCl43)22)2. Absorption capacity of the polymer also depends on pH, particle size and drying temperature. The effect of water retention in sandy soil, the spectral characteristics XRD, FT-IR were also studied. (author)

  15. Electromagnetic behavior of radar absorbing materials based on Ca hexaferrite modified with Co-Ti ions and doped with La

    Valdirene Aparecida da Silva

    2009-06-01

    Full Text Available Radar Absorbing Materials (RAM are compounds that absorb incidental electromagnetic radiation in tuned frequencies and dissipate it as heat. Its preparation involves the adequate processing of polymeric matrices filled with compounds that act as radar absorbing centers in the microwave range. This work shows the electromagnetic evaluation of RAM based on CoTi and La doped Ca hexaferrite. Vibrating Sample Magnetization analyses show that ion substitution promoted low values for the parameters of saturation magnetization (123.65 Am2/kg and coercive field (0.07 T indicating ferrite softening. RAM samples obtained using different hexaferrite concentrations (40-80 per cent, w/w show variations in complex permeability and permittivity parameters and also in the performance of incidental radiation attenuation. Microwave attenuation values between 40 and 98 per cent were obtained.

  16. Evaluation of the acoustic and non-acoustic properties of sound absorbing materials using a three-microphone impedance tube

    Doutres, Olivier; Atalla, Noureddine; Panneton, Raymond; 10.1016/j.apacoust.2010.01.007

    2010-01-01

    This paper presents a straightforward application of an indirect method based on a three-microphone impedance tube setup to determine the non-acoustic properties of a sound absorbing porous material. First, a three-microphone impedance tube technique is used to measure some acoustic properties of the material (i.e., sound absorption coefficient, sound transmission loss, effective density and effective bulk modulus) regarded here as an equivalent fluid. Second, an indirect characterization allows one to extract its non-acoustic properties (i.e., static airflow resistivity, tortuosity, viscous and thermal characteristic lengths) from the measured effective properties and the material open porosity. The procedure is applied to four different sound absorbing materials and results of the characterization are compared with existing direct and inverse methods. Predictions of the acoustic behavior using an equivalent fluid model and the found non-acoustic properties are in good agreement with impedance tube measureme...

  17. Study of diluting and absorber materials to control the reactivity during a postulated core meltdown accident in generation IV reactors

    In order to limit the consequences of a hypothetical core meltdown accident in Generation IV Sodium Fast Reactors, absorber materials in or near the core, such as boron carbide B4C, and diluting materials in the core catcher will be used to prevent recriticality within the mixture of molten oxide fuel and molten structures called corium. The aim of the PhD thesis was to select materials of both types and to understand their behaviour during their interaction with corium, from chemical and thermodynamic points of view. Concerning B4C, thermodynamic calculations and experiments agree with the formation of two immiscible phases at high temperature in the B4C - UO2 system: one oxide and one boride. This separation of phases can reduce the efficiency of the neutrons absorption inside the molten fuel contained in the oxide phase. Moreover, volatilization of a part of the boron element can occur. According to these results, the necessary quantity of B4C to be introduced should be reconsidered for postulated severe accident sequence. Other solution could be the use of Eu2O3 or HfO2 as absorber material. These oxides form a solid solution with the oxide fuel. Concerning the diluting materials, mixed oxides Al2O3 - HfO2 and Al2O3 - Eu2O3 were preselected. These systems being completely unknown to date at high temperature in association with UO2, first points on the corresponding ternary phase diagrams were researched. Contrary to Al2O3 - Eu2O3 - UO2 system, the Al2O3 - HfO2 - UO2 mixture presents only one eutectic and thus only one solidification path which makes easier forecasting the behaviour of corium in the core catcher. (author)

  18. Efficiency increase of two-step-sensitized inorganic/organic hybrid absorber materials

    Mankel, Eric; Mayer, Thomas; Jaegermann, Wolfram [Technische Universitaet Darmstadt (Germany). Materials Science Institute, Surface Science Division

    2009-07-01

    Photovoltaic third generation concepts promise a significant increase of energy conversion efficiency. Two-step sensitization of inorganic wide band gap matrices by incorporated organic donor-acceptor molecules (e.g. dyads) has been suggested as possible means of creating third generation absorbers. Based on the model of Shockley and Queisser we calculate the rise of the ultimate efficiency and the detailed balance limit of a sensitized p-n-junction by adding a sensitization current provided by the organic molecules to the photocurrent provided by the matrix material. The model includes the dependence of a number of parameters namely the band gap of the matrix material, the energetic position of the organic frontier orbitals relative to the matrix band edges, the lifetime of the first excited molecular state and the Gaussian width of the absorption curve of the dye. For a width of 0.25eV an overall maximum efficiency of 45% has been calculated. To reach this limit under AM1.5 conditions the lifetime of the excited state must be longer than 10ms. Finally the calculations have been applied on ZnSe/CuPc/PTCDA composites using the band alignment as experimentally determined by XPS/UPS measurements.

  19. A Novel, Real-Valued Genetic Algorithm for Optimizing Radar Absorbing Materials

    Hall, John Michael

    2004-01-01

    A novel, real-valued Genetic Algorithm (GA) was designed and implemented to minimize the reflectivity and/or transmissivity of an arbitrary number of homogeneous, lossy dielectric or magnetic layers of arbitrary thickness positioned at either the center of an infinitely long rectangular waveguide, or adjacent to the perfectly conducting backplate of a semi-infinite, shorted-out rectangular waveguide. Evolutionary processes extract the optimal physioelectric constants falling within specified constraints which minimize reflection and/or transmission over the frequency band of interest. This GA extracted the unphysical dielectric and magnetic constants of three layers of fictitious material placed adjacent to the conducting backplate of a shorted-out waveguide such that the reflectivity of the configuration was 55 dB or less over the entire X-band. Examples of the optimization of realistic multi-layer absorbers are also presented. Although typical Genetic Algorithms require populations of many thousands in order to function properly and obtain correct results, verified correct results were obtained for all test cases using this GA with a population of only four.

  20. X-ray conversion efficiency as a function of atomic number for 0.26-micron-laser - Irradiated targets

    Alaterre, P.; Pepin, H.; Fabbro, R.; Faral, B.

    1986-11-01

    Soft-X-ray low-resolution experimental spectra are obtained for a large set of targets irradiated at 2 x 10 to the 14th W/sq cm by 0.26-micron radiation. X-ray conversion efficiencies in various spectral ranges are studied as a function of atomic number. To calculate the emissivity, a simple, multiple-Z atomic-physics model is developed based on a screened-hydrogenic description for the atomic structure and on a non-LTE modified Saha approach to plasma-ionization properties. Experimental soft-X-ray spectra are replicated by using a discrete summation of emissivities over a few temperatures with appropriate weighting factors determined from the experiment or through a separate hydrodynamic-code simulation. The modulations in the Z dependence of the X-ray conversion efficiency in various spectral ranges are well described and interpreted.

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

    Han, I; Demir, L

    2010-01-01

    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. PMID:20421703

  2. A new method to measure electron density and effective atomic number using dual-energy CT images

    Ramos Garcia, Luis Isaac; Pérez Azorin, José Fernando; Almansa, Julio F.

    2016-01-01

    The purpose of this work is to present a new method to extract the electron density ({ρ\\text{e}} ) and the effective atomic number (Z eff) from dual-energy CT images, based on a Karhunen-Loeve expansion (KLE) of the atomic cross section per electron. This method was used to calibrate a Siemens Definition CT using the CIRS phantom. The predicted electron density and effective atomic number using 80 kVp and 140 kVp were compared with a calibration phantom and an independent set of samples. The mean absolute deviations between the theoretical and calculated values for all the samples were 1.7 %  ±  0.1 % for {ρ\\text{e}} and 4.1 %  ±  0.3 % for Z eff. Finally, these results were compared with other stoichiometric method. The application of the KLE to represent the atomic cross section per electron is a promising method for calculating {ρ\\text{e}} and Z eff using dual-energy CT images.

  3. Studies on mass attenuation coefficients, effective atomic numbers and electron densities for CoCuAg alloy thin film

    Apaydın, G.; Cengiz, E.; Tıraşoğlu, E.; Aylıkcı, V.; Bakkaloğlu, Ö. F.

    2009-05-01

    The mass attenuation coefficients for the elements Co, Cu and Ag and a thin film of CoCuAg alloy were measured in the energy range 4.029-38.729 keV. Effective atomic numbers and electron densities were calculated by using these coefficients. The energies were obtained by using secondary targets that were irradiated with gamma-ray photons of 241Am. The x-rays were counted by using a Canberra Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The results were compared with theoretical calculated values and fairly good agreement was found between them within an average experimental error. The mass attenuation coefficients, effective atomic numbers and electron densities were plotted versus photon energy.

  4. Studies on mass attenuation coefficients, effective atomic numbers and electron densities for CoCuAg alloy thin film

    The mass attenuation coefficients for the elements Co, Cu and Ag and a thin film of CoCuAg alloy were measured in the energy range 4.029-38.729 keV. Effective atomic numbers and electron densities were calculated by using these coefficients. The energies were obtained by using secondary targets that were irradiated with gamma-ray photons of 241Am. The x-rays were counted by using a Canberra Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The results were compared with theoretical calculated values and fairly good agreement was found between them within an average experimental error. The mass attenuation coefficients, effective atomic numbers and electron densities were plotted versus photon energy.

  5. Studies on effective atomic numbers, electron densities from mass attenuation coefficients near the K edge in some samarium compounds.

    Akman, F; Durak, R; Turhan, M F; Kaçal, M R

    2015-07-01

    The effective atomic numbers and electron densities of some samarium compounds were determined using the experimental total mass attenuation coefficient values near the K edge in the X-ray energy range from 36.847 up to 57.142 keV. The measurements, in the region from 36.847 to 57.142 keV, were done in a transmission geometry utilizing the Kα2, Kα1, Kβ1 and Kβ2 X-rays from different secondary source targets excited by the 59.54 keV gamma-photons from an Am-241 annular source. This paper presents the first measurement of the effective atomic numbers and electron densities for some samarium compounds near the K edge. The results of the study showed that the measured values were in good agreement with the theoretically calculated ones. PMID:25880612

  6. Determination of atomic number and composition of human enamel; Determinacao da composicao e numero atomico efetivo do esmalte humano

    Nogueira, M.S. [Centro Regional de Ciencias Nucleares (CRCN), Recife, PE (Brazil); Rodas Duran, J.E. [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica e Matematica

    2001-07-01

    The teeth are organs of complicated structure that consist, partly, of hard tissue containing in its interior the dental pulp, rich in vases and nerves. The main mass of the tooth is constituted by the dentine, which is covered with hard tissues and of epithelial origin called enamel. The dentine of the human teeth used in this work were completely removed and the teeth were cut with a device with a diamond disc. In this work the chemical composition of the human enamel was determined, which showed a high percentage of Ca and P, in agreement with the results found in the literature. The effective atomic number of the material and the half-value layer in the energy range of diagnostic X-ray beams were determined. Teeth could be used to evaluated the public's individual doses as well as for retrospective dosimetry what confirms the importance of their effective atomic number and composition determination. (author)

  7. Accuracies of the synthesized monochromatic CT numbers and effective atomic numbers obtained with a rapid kVp switching dual energy CT scanner

    Purpose: This study was performed to investigate the accuracies of the synthesized monochromatic images and effective atomic number maps obtained with the new GE Discovery CT750 HD CT scanner. Methods: A Gammex-RMI model 467 tissue characterization phantom and the CT number linearity section of a Phantom Laboratory Catphan 600 phantom were scanned using the dual energy (DE) feature on the GE CT750 HD scanner. Synthesized monochromatic images at various energies between 40 and 120 keV and effective atomic number (Zeff) maps were generated. Regions of interest were placed within these images/maps to measure the average monochromatic CT numbers and average Zeff of the materials within these phantoms. The true Zeff values were either supplied by the phantom manufacturer or computed using Mayneord's equation. The linear attenuation coefficients for the true CT numbers were computed using the NIST XCOM program with the input of manufacturer supplied elemental compositions and densities. The effects of small variations in the assumed true densities of the materials were also investigated. Finally, the effect of body size on the accuracies of the synthesized monochromatic CT numbers was investigated using a custom lumbar section phantom with and without an external fat-mimicking ring. Results: Other than the Zeff of the simulated lung inserts in the tissue characterization phantom, which could not be measured by DECT, the Zeff values of all of the other materials in the tissue characterization and Catphan phantoms were accurate to 15%. The accuracies of the synthesized monochromatic CT numbers of the materials in both phantoms varied with energy and material. For the 40-120 keV range, RMS errors between the measured and true CT numbers in the Catphan are 8-25 HU when the true CT numbers were computed using the nominal plastic densities. These RMS errors improve to 3-12 HU for assumed true densities within the nominal density ±0.02 g/cc range. The RMS errors between the

  8. Studies on the effective atomic numbers of some human tissues in the energy region 15-100 keV

    The effective atomic numbers for total photon interaction in muscle, bone, brain, heart, kidney, liver, lungs, ovaries, pancreas, spleen and tongue are evaluated using three different methods, for practical use in the energy region 15-100 keV. Muscle, brain, heart, kidney, lungs, ovaries, pancreas, spleen, tongue and water, bone and silicon; liver and oxygen are found to behave in an approximately similar manner in this energy region. (author)

  9. Studies on effective atomic numbers, electron densities from mass attenuation coefficients near the K edge in some samarium compounds

    The effective atomic numbers and electron densities of some samarium compounds were determined using the experimental total mass attenuation coefficient values near the K edge in the X-ray energy range from 36.847 up to 57.142 keV. The measurements, in the region from 36.847 to 57.142 keV, were done in a transmission geometry utilizing the Kα2, Kα1, Kβ1 and Kβ2 X-rays from different secondary source targets excited by the 59.54 keV gamma-photons from an Am-241 annular source. This paper presents the first measurement of the effective atomic numbers and electron densities for some samarium compounds near the K edge. The results of the study showed that the measured values were in good agreement with the theoretically calculated ones. - Highlights: • The effective atomic numbers and electron densities determined for some samarium compounds from total mass attenuation coefficients near the K edge. • The measurements performed using secondary excitation geometry and a Si(Li) detector. • The experimental results compared with the theoretical calculation

  10. Determination of the number of atoms present in nano contact based on shot noise measurements with highly stable nano-fabricated electrodes.

    Takahashi, Ryoji; Kaneko, Satoshi; Marqués-González, Santiago; Fujii, Shintaro; Nishino, Tomoaki; Tsukagoshi, Kazuhito; Kiguchi, Manabu

    2016-07-22

    A highly stable experimental setup was developed for the measurement of shot noise in atomic contacts and molecular junctions to determine the number of atoms or molecules present. The use of a nano-fabricated mechanically controllable break junction (MCBJ) electrode improved the overall stability of the experimental setup. The improved stability of the system and optimization of measurement system enabled us to comprehensively investigate the shot noise as well as charge transport properties in Au atomic contacts and molecular junctions. We present a solid proof that the number of atoms (cross sectional atom) in the Au atomic contacts was exactly one. In the atomic contacts, contribution from the additional channels was under the detection limit. Furthermore, the effect of molecular adsorption on the charge transport in the Au atomic contact was investigated. Additional transport channels were opened by exposing pyrazine molecules to the Au contacts, which gave rise to an increase in the Fano factor in the shot noise. PMID:27291763

  11. Determination of the number of atoms present in nano contact based on shot noise measurements with highly stable nano-fabricated electrodes

    Takahashi, Ryoji; Kaneko, Satoshi; Marqués-González, Santiago; Fujii, Shintaro; Nishino, Tomoaki; Tsukagoshi, Kazuhito; Kiguchi, Manabu

    2016-07-01

    A highly stable experimental setup was developed for the measurement of shot noise in atomic contacts and molecular junctions to determine the number of atoms or molecules present. The use of a nano-fabricated mechanically controllable break junction (MCBJ) electrode improved the overall stability of the experimental setup. The improved stability of the system and optimization of measurement system enabled us to comprehensively investigate the shot noise as well as charge transport properties in Au atomic contacts and molecular junctions. We present a solid proof that the number of atoms (cross sectional atom) in the Au atomic contacts was exactly one. In the atomic contacts, contribution from the additional channels was under the detection limit. Furthermore, the effect of molecular adsorption on the charge transport in the Au atomic contact was investigated. Additional transport channels were opened by exposing pyrazine molecules to the Au contacts, which gave rise to an increase in the Fano factor in the shot noise.

  12. Analysis and theoretical description of a number of atomic systems with optical 3d-electrons

    The goal of the investigation was to obtain knowledge of spectra of multiple ionized atoms in which 3d electrons play an important role. Two vacuum spectrographs were used: a 6.650 m normal incidence spectrograph for the region 400 A < lambda < 2400 A and a 6.600 m grazing incidence spectrograph for the region below 600 A. In the first five chapters the classification of several thousands of lines in the spectra Co V, Ni V, Cu V, Ni VI and Cu VI is given together with the determination of levels in the 3dsup(n), 3dsup(n-1)4s and 3dsup(n-1)4p configurations in these spectra. The position of the levels has been calculated by means of the parameter method. The calculated level values have been fitted to the experimentally determined values by means of a least squares fit procedure, resulting in optimum parameter values. The parameter values of this final diagonalization have been compared with each other along the sequence Cr-Cu for the 2-5 times ionized atoms. This comparison is discussed in chapter VI. In the last chapter (VII) the application of data, obtained from the analyses of spectra of Fe and Ni ions is considered in the field of astrophysics. The presence of forbidden lines, due to magnetic dipole transitions, of Fe IV, V, VI and VII and Ni IV, V, VI and VII in the spectra of the variable stars RR Telescopii and Eta Carinae is discussed. (Auth.)

  13. Tomography of atomic number and density of materials using dual-energy imaging and the Alvarez and Macovski attenuation model

    Paziresh, M.; Kingston, A. M.; Latham, S. J.; Fullagar, W. K.; Myers, G. M.

    2016-06-01

    Dual-energy computed tomography and the Alvarez and Macovski [Phys. Med. Biol. 21, 733 (1976)] transmitted intensity (AMTI) model were used in this study to estimate the maps of density (ρ) and atomic number (Z) of mineralogical samples. In this method, the attenuation coefficients are represented [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)] in the form of the two most important interactions of X-rays with atoms that is, photoelectric absorption (PE) and Compton scattering (CS). This enables material discrimination as PE and CS are, respectively, dependent on the atomic number (Z) and density (ρ) of materials [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)]. Dual-energy imaging is able to identify sample materials even if the materials have similar attenuation coefficients at single-energy spectrum. We use the full model rather than applying one of several applied simplified forms [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976); Siddiqui et al., SPE Annual Technical Conference and Exhibition (Society of Petroleum Engineers, 2004); Derzhi, U.S. patent application 13/527,660 (2012); Heismann et al., J. Appl. Phys. 94, 2073-2079 (2003); Park and Kim, J. Korean Phys. Soc. 59, 2709 (2011); Abudurexiti et al., Radiol. Phys. Technol. 3, 127-135 (2010); and Kaewkhao et al., J. Quant. Spectrosc. Radiat. Transfer 109, 1260-1265 (2008)]. This paper describes the tomographic reconstruction of ρ and Z maps of mineralogical samples using the AMTI model. The full model requires precise knowledge of the X-ray energy spectra and calibration of PE and CS constants and exponents of atomic number and energy that were estimated based on fits to simulations and calibration measurements. The estimated ρ and Z images of the samples used in this paper yield average relative errors of 2.62% and 1.19% and maximum relative errors of 2.64% and 7.85%, respectively. Furthermore, we demonstrate that the method accounts for the beam hardening effect in density (ρ) and

  14. Self-shielding and burn-out effects in the irradiation of strongly-neutron-absorbing material

    Self-shielding and burn-out effects are discussed in the evaluation of radioisotopes formed by neutron irradiation of a strongly-neutron-absorbing material. A method of the evaluation of such effects is developed both for thermal and epithermal neutrons. Gadolinium oxide uniformly mixed with graphite powder was irradiated by reactor-neutrons together with pieces of a Co-Al alloy wire (the content of Co being 0.475%) as the neutron flux monitor. The configuration of the samples and flux monitors in each of two irradiations is illustrated. The yields of activities produced in the irradiated samples were determined by the γ-spectrometry with a Ge(Li) detector of a relative detection efficiency of 8%. Activities at the end of irradiation were estimated by corrections due to pile-up, self-absorption, detection efficiency, branching ratio, and decay of the activity. Results of the calculation are discussed in comparison with the observed yields of 153Gd, 160Tb, and 161Tb for the case of neutron irradiation of disc-shaped targets of gadolinium oxide. (T.G.)

  15. Hypernuclei formation probability as a function of the atomic mass number A

    Bonomi, G.; Finuda Collaboration

    2012-09-01

    The creation of a hypernucleus [2], that is a nucleus in which a nucleon is replaced by an hyperon, requires the injection of strangeness into the nucleus. This is possible in different ways [3], mainly using π+ or K- beams on nuclear targets; recently, also electron beams have been used. The FINUDA experiment at the DAΦNE Φ factory of the INFN "Laboratori Nazionali di Frascati" produced Λ-hypernuclei by stopping, in thin nuclear targets (0.1-0.2 g/cm2), the negative kaons originating from the Φ decay through the strangeness-exchange reaction Kstop-+AZ→A/ΛZ+π-, where AZ indicates the target nucleus and A/ΛZ the Λ hypernucleus in which a Λ particle replaced a neutron. FINUDA, an unconventional and innovative apparatus, allowed the positioning of 8 different target modules around the interaction region. In this way different targets could be studied contemporaneously, with the same apparatus and with the same analysis technique, allowing for a direct comparison between different nuclei. In particular FINUDA could study the production of Λ-hypernuclei on 7Li, 9Be, 12C, 13C and 16O targets. Both the Λ binding energy and the hypernuclei production probabilities have been measured [1]. The new measurements on 7/ΛLi, 9/ΛBe, 13/ΛC and 16/ΛO, along with previous measurements on 12/ΛC, allowed for a meaningful study of the formation of p-shell hypernuclei from the two-body capture of K- at rest, giving for the first time the possibility of disentangling the effects due to atomic wave-function of the captured K- from those due to the pion optical nuclear potential and from those due to the specific hypernuclear states [4].

  16. Atomic Number Dependence of Hadron Production at Large Transverse Momentum in 300 GeV Proton--Nucleus Collisions

    Cronin, J. W.; Frisch, H. J.; Shochet, M. J.; Boymond, J. P.; Mermod, R.; Piroue, P. A.; Sumner, R. L.

    1974-07-15

    In an experiment at the Fermi National Accelerator Laboratory we have compared the production of large transverse momentum hadrons from targets of W, Ti, and Be bombarded by 300 GeV protons. The hadron yields were measured at 90 degrees in the proton-nucleon c.m. system with a magnetic spectrometer equipped with 2 Cerenkov counters and a hadron calorimeter. The production cross-sections have a dependence on the atomic number A that grows with P{sub 1}, eventually leveling off proportional to A{sup 1.1}.

  17. Effective atomic number and mass attenuation coefficient of PbO-BaO-B2O3 glass system

    Issa, Shams A. M.

    2016-03-01

    Gamma-rays attenuation coefficient, half-value layer, mean free path, effective atomic number and electron density have been measured in glass system of xPbO-(50-x) BaO-50B2O3 (where 5≤x≤45 mol%) for gamma ray photon energies of 0.356, 0.662, 1.173 and 1.33 MeV. The emitted gamma ray was detected by 3×3 in. NaI(Tl) scintillation gamma ray spectrometers. The results were found in good agreement with the theoretical values which calculated from WinXcom.

  18. Study of mass attenuation coefficients and effective atomic numbers of bismuth-ground granulated blast furnace slag concretes

    Kumar, Sandeep; Singh, Sukhpal

    2016-05-01

    Five samples of Bismuth-Ground granulated blast furnace slag (Bi-GGBFS) concretes were prepared using composition (0.6 cement + x Bi2O3 + (0.4-x) GGBFS, x = 0.05, 0.10, 0.15, 0.20 and 0.25) by keeping constant water (W) cement (C) ratio. Mass attenuation coefficients (μm) of these prepared samples were calculated using a computer program winXCOM at different gamma ray energies, whereas effective atomic numbers (Zeff) is calculated using mathematical formulas. The radiation shielding properties of Bi-GGBFS concrete has been compared with standard radiation shielding concretes.

  19. Development of FeCoB/Graphene Oxide based microwave absorbing materials for X-Band region

    This work explored the microwave absorption capability of Graphene Oxide and Graphene Oxide coated with FeCoB for stealth technology. Epoxy based microwave absorbing materials were prepared with 30% loading of Graphene Oxide, FeCoB alloy and Graphene Oxide coated with FeCoB. Graphene Oxide and FeCoB were synthesized by Hummer's and Co-precipitation methods, respectively. The filler particles were characterized by FESEM, XRD and Vibrating Sample Magnetometer techniques. Permittivity, permeability and reflection loss values of the composite absorbers were measured with vector network analyzer which showed a reflection loss value of −7.86 dB, at 10.72 GHz, for single layered Graphene Oxide/Epoxy based microwave absorbers which can be correlated to the absorption of about 83.97% of the incident microwave energy. Reflection loss value of FeCoB/Epoxy based microwave absorber showed −13.30 dB at 11.67 GHz, which corresponded to maximum absorption of 93.8%. However, reflection loss values of Graphene Oxide coated with FeCoB/Epoxy based single-layer absorber increased to −22.24 dB at 12.4 GHz which corresponds to an absorption of 99% of the incident microwave energy. - Highlights: • FeCoB coated Graphene Oxide (GO) was synthesized by co-precipitation method. • GO, FeCoB and GO@FeCoB based microwave absorbers were developed with Epoxy matrix. • GO and FeCoB/Epoxy absorbers showed −7.86 & −13.30 dB reflection loss, respectively. • Maximum Reflection loss of −22.24 dB was achieved with GO@FeCoB/Epoxy absorber

  20. Measurement of attenuation coefficient, effective atomic number and electron density of oxides of lanthanides by using simplified ATM-method

    Highlights: • Measurement of linear attenuation coefficient by simplified ATM method for the oxides of Lanthanides. • Atomic parameters are calculated from linear attenuation coefficients. • Geometrical setup has been validated with metallic targets of uniform thickness. • Experimental results are in good agreement with theoretical results within error limits. - Abstract: The linear and mass attenuation coefficient of non-uniform thick samples of oxides of lanthanide (Pr6O11, Nd2O3, Gd2O3, Tb4O7, Ho2O3 and Er2O3) has been measured by gamma ray photons of energy 59.54 keV obtained from 100 mCi radioactive source of 241Am. Advanced Two Media (ATM) methods Gupta et al. (2013) is simplified by considering air as first medium and metallic foil as second medium. In the present measurements this consideration simplifies the mathematical complexities and laboratory work to find the attenuation coefficients of non-uniform thick samples. The values of attenuation coefficient were then used to calculate effective atomic numbers (Zeff), interaction cross-section (σ) and effective electron densities (Neff) of lanthanide oxides. The method is validated by measuring linear/mass attenuation coefficient and other parameters for Mo, Ag, Sn, W and Pb of uniform thickness. The measured results are compared with the theoretical values from WinXcom Gerward et al. (2001). It is found that measured values are in agreement within 2% of theoretical results. The measurement of linear attenuation coefficient, effective atomic numbers (Zeff), interaction cross-section and effective electron densities (Neff) enhances the understanding of material characteristics. Presently studied materials i.e. oxides of Lanthanide are widely used as glass colouring agent and in electronic sensing devices

  1. Measurement of attenuation coefficient, effective atomic number and electron density of oxides of lanthanides by using simplified ATM-method

    Singh, Gurinderjeet; Gupta, Manoj Kumar, E-mail: mkgupta.sliet@gmail.com; Dhaliwal, A.S.; Kahlon, K.S.

    2015-01-15

    Highlights: • Measurement of linear attenuation coefficient by simplified ATM method for the oxides of Lanthanides. • Atomic parameters are calculated from linear attenuation coefficients. • Geometrical setup has been validated with metallic targets of uniform thickness. • Experimental results are in good agreement with theoretical results within error limits. - Abstract: The linear and mass attenuation coefficient of non-uniform thick samples of oxides of lanthanide (Pr{sub 6}O{sub 11}, Nd{sub 2}O{sub 3}, Gd{sub 2}O{sub 3}, Tb{sub 4}O{sub 7}, Ho{sub 2}O{sub 3} and Er{sub 2}O{sub 3}) has been measured by gamma ray photons of energy 59.54 keV obtained from 100 mCi radioactive source of {sup 241}Am. Advanced Two Media (ATM) methods Gupta et al. (2013) is simplified by considering air as first medium and metallic foil as second medium. In the present measurements this consideration simplifies the mathematical complexities and laboratory work to find the attenuation coefficients of non-uniform thick samples. The values of attenuation coefficient were then used to calculate effective atomic numbers (Z{sub eff}), interaction cross-section (σ) and effective electron densities (N{sub eff}) of lanthanide oxides. The method is validated by measuring linear/mass attenuation coefficient and other parameters for Mo, Ag, Sn, W and Pb of uniform thickness. The measured results are compared with the theoretical values from WinXcom Gerward et al. (2001). It is found that measured values are in agreement within 2% of theoretical results. The measurement of linear attenuation coefficient, effective atomic numbers (Z{sub eff}), interaction cross-section and effective electron densities (N{sub eff}) enhances the understanding of material characteristics. Presently studied materials i.e. oxides of Lanthanide are widely used as glass colouring agent and in electronic sensing devices.

  2. Effective atomic numbers for materials of medical interest at low photon energy using the Rayleigh to Compton scattering ratio

    Del Lama, L. S.; Soares, L. D. H.; Antoniassi, M.; Poletti, M. E.

    2015-06-01

    The Rayleigh to Compton scattering ratio (R/C) has been used as a reliable quantitative method for materials analysis, especially biological ones Unlike the conventional transmission method, which is sensitive to linear attenuation coefficients, the R/C ratio is more useful for situations where the μ variations are small and the atomic number variations become more significant. In the present study, gamma rays from an 241Am source with an energy of 59.54 keV were used to determine the effective atomic numbers for several materials considering the conventional total cross-section based method (ZeffATTEN) and also the intensity ratio between elastic (Rayleigh) and inelastic (Compton) scattered photons (ZeffR/C). Common liquid and solid compounds used as phantoms for investigation of radiation interaction effects on biological tissues were analyzed. This work aimed to use the R/C method in choosing the most suitable phantom to simulate biological tissues, considering two different experimental conditions: attenuation and scattering. The Rayleigh to Compton scattering ratio was shown to be a complementary approach to assist in the selection of appropriate tissue substitute materials.

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

    Full text: For many practical purposes in radiation biology, dosimetry, and medical diagnostics and therapy, it is convenient to characterize the radiation response of a given material by a single parameter, such as the effective atomic number. Among early applications one may mention the determination of fat content of liver, and calcium content in bone densitometry. Originally, calculations of the effective atomic number, Zeff, were based on empirical relations for the Z dependence of the X-ray or gamma ray mass attenuation coefficient. Today, the availability of large databases of photon interaction cross sections has made it possible to calculate Zeff with much improved accuracy and information content over wide ranges of photon energies. An example for lauric acid is shown in this abstract. Mass attenuation coefficients and interaction cross sections of bio-molecules have been generated by the computer program WinXCom. In addition to saving the user for manual interpolation, WinXCom makes it possible to export the cross-sectional data to a predefined MS Excel template, thus greatly facilitating graphical and numerical data treatment. Rigorous calculations of Zeff for total and partial interaction processes will be discussed. We have used a comprehensive set of formulas, valid for all types of materials and for all energies greater than 1 keV

  4. Number distribution of multiply emitted secondary electrons (MUSE) produced by atomic and molecular ion impacts on thin foils

    The number distribution of secondary electrons emitted through energetic ion impact on a thin carbon foil was measured. Projectile ions of 1-MeV/u He2+ or He+ passed through a carbon foil with thickness of 1 μ g/cm2 in a direction of 45o to its surface. Electrons emitted in the forward and backward directions were accelerated by a potential applied to the foil and detected by two solid state detectors (SSDs) in which pulses proportional to the electron number were formed. Transmitted ions were charge analyzed by an electrostatic deflector and detected by the third SSD. The measurement was performed in coincidence with transmitted He2+ ions and in the event-recording mode. For molecular ions, Coulomb explosion fragments, i.e., two He2+ ions were detected after passing an annular slit or conventional circular slit which selects incident molecules with molecular axes perpendicular to or parallel to the ion velocity. The average numbers of electrons emitted in the forward direction are about 1.5 times as large as those in the backward direction for atomic and molecular ions with both orientations. The width of the number distribution is generally wider than that of Poisson distribution with the same average number. Orientation dependence is not recognized in the backward direction but a slight enhancement is found for parallel orientation in the forward direction. The fact that the vicinage effect is observed only for the parallel orientation seems consistent with the density enhancement of the target electrons behind the leading ion. A negative correlation between numbers of electrons emitted in the forward and backward directions is found. (Author)

  5. High fidelity simulation and analysis of liquid jet atomization in a gaseous crossflow at intermediate Weber numbers

    Li, Xiaoyi; Soteriou, Marios C.

    2016-08-01

    Recent advances in numerical methods coupled with the substantial enhancements in computing power and the advent of high performance computing have presented first principle, high fidelity simulation as a viable tool in the prediction and analysis of spray atomization processes. The credibility and potential impact of such simulations, however, has been hampered by the relative absence of detailed validation against experimental evidence. The numerical stability and accuracy challenges arising from the need to simulate the high liquid-gas density ratio across the sharp interfaces encountered in these flows are key reasons for this. In this work we challenge this status quo by presenting a numerical model able to deal with these challenges, employing it in simulations of liquid jet in crossflow atomization and performing extensive validation of its results against a carefully executed experiment with detailed measurements in the atomization region. We then proceed to the detailed analysis of the flow physics. The computational model employs the coupled level set and volume of fluid approach to directly capture the spatiotemporal evolution of the liquid-gas interface and the sharp-interface ghost fluid method to stably handle high liquid-air density ratio. Adaptive mesh refinement and Lagrangian droplet models are shown to be viable options for computational cost reduction. Moreover, high performance computing is leveraged to manage the computational cost. The experiment selected for validation eliminates the impact of inlet liquid and gas turbulence and focuses on the impact of the crossflow aerodynamic forces on the atomization physics. Validation is demonstrated by comparing column surface wavelengths, deformation, breakup locations, column trajectories and droplet sizes, velocities, and mass rates for a range of intermediate Weber numbers. Analysis of the physics is performed in terms of the instability and breakup characteristics and the features of downstream

  6. Standard guide for establishing surveillance test program for boron-based neutron absorbing material systems for use in nuclear spent fuel storage racks

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This guide provides guidance for establishing a surveillance test program to monitor the performance of boron-based neutron absorbing material systems (absorbers) necessary to maintain sub-criticality in nuclear spent fuel storage racks in a pool environment. The practices presented in this guide, when implemented, will provide a comprehensive surveillance test program to verify the presence of sufficient neutron absorbing material within the storage racks. The performance of a surveillance test program provides added assurance of the safe and effective operation of a high-density storage facility for nuclear spent fuel. 1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  7. Absorber materials, control rods and designs of shutdown systems for advanced liquid metal fast reactors. Proceeding of a technical committee meeting

    Thirty-five specialists from France, Germany, India, Japan, the Republic of Kazakhsan, the Russian Federation and the Republic of Georgia (observer) attended the meeting. The meeting had seven sessions. The main topics of discussions were: Status of control rod designs for fast reactors and experience with operation; properties and behaviour of absorber materials for control rods; results of post-irradiation examination of absorber materials, and mechanisms affecting their properties and behaviour; design of a backup reactivity shutdown system utilizing passive mechanisms: Curie point electromagnetic mechanism; enhancement of thermal expansion of absorber rdo drive lines; hydraulically suspended control rods; gas expansion modules in the core; and the possibility of optimizing the reactivity coefficients and the efficiency of Pu burning by using absorber and moderator materials in the core. A total of 23 papers were presented, and a technical tour of the IPPE also took place. Refs, figs, tabs

  8. Variation of 3s photoionization resonance structures in a serial atomic number species Ar, K, and Ca

    Subvalence 3s-shell photoionization resonances of Ca were measured with monochromatized synchrotron radiation and photoion time-of-flight spectroscopy method. Charge resolved photoion yield spectra were obtained. Broad peak structures were found in the Ca+ spectrum and shallow window structures were found in the Ca2+ spectrum. We performed MCDF calculations to assign the resonance structures. The 3s-shell photoionization of Ar and K were also measured for comparison. A systematic increase was observed in Fano-Beutler parameter and in the resonance width along with the increase of atomic number from Z=18(Ar) to 20(Ca). We discuss also the spectral structures that could be of the 3p double-shake-up satellites, which are observed in the 3s photoionization region. (author)

  9. Technical Note: Exploring the limit for the conversion of energy-subtracted CT number to electron density for high-atomic-number materials

    Purpose: For accurate tissue inhomogeneity correction in radiotherapy treatment planning, the authors had previously proposed a novel conversion of the energy-subtracted CT number to an electron density (ΔHU–ρe conversion), which provides a single linear relationship between ΔHU and ρe over a wide ρe range. The purpose of this study is to address the limitations of the conversion method with respect to atomic number (Z) by elucidating the role of partial photon interactions in the ΔHU–ρe conversion process. Methods: The authors performed numerical analyses of the ΔHU–ρe conversion for 105 human body tissues, as listed in ICRU Report 46, and elementary substances with Z = 1–40. Total and partial attenuation coefficients for these materials were calculated using the XCOM photon cross section database. The effective x-ray energies used to calculate the attenuation were chosen to imitate a dual-source CT scanner operated at 80–140 kV/Sn under well-calibrated and poorly calibrated conditions. Results: The accuracy of the resultant calibrated electron density,ρecal, for the ICRU-46 body tissues fully satisfied the IPEM-81 tolerance levels in radiotherapy treatment planning. If a criterion of ρecal/ρe − 1 is assumed to be within ±2%, the predicted upper limit of Z applicable for the ΔHU–ρe conversion under the well-calibrated condition is Z = 27. In the case of the poorly calibrated condition, the upper limit of Z is approximately 16. The deviation from the ΔHU–ρe linearity for higher Z substances is mainly caused by the anomalous variation in the photoelectric-absorption component. Conclusions: Compensation among the three partial components of the photon interactions provides for sufficient linearity of the ΔHU–ρe conversion to be applicable for most human tissues even for poorly conditioned scans in which there exists a large variation of effective x-ray energies owing to beam-hardening effects arising from the mismatch between the

  10. Technical Note: Exploring the limit for the conversion of energy-subtracted CT number to electron density for high-atomic-number materials

    Saito, Masatoshi, E-mail: masaito@clg.niigata-u.ac.jp [Department of Radiological Technology, School of Health Sciences, Faculty of Medicine, Niigata University, Niigata 951-8518 (Japan); Tsukihara, Masayoshi [Division of Radiological Technology, Graduate School of Health Sciences, Niigata University, Niigata 951-8518 (Japan)

    2014-07-15

    Purpose: For accurate tissue inhomogeneity correction in radiotherapy treatment planning, the authors had previously proposed a novel conversion of the energy-subtracted CT number to an electron density (ΔHU–ρ{sub e} conversion), which provides a single linear relationship between ΔHU and ρ{sub e} over a wide ρ{sub e} range. The purpose of this study is to address the limitations of the conversion method with respect to atomic number (Z) by elucidating the role of partial photon interactions in the ΔHU–ρ{sub e} conversion process. Methods: The authors performed numerical analyses of the ΔHU–ρ{sub e} conversion for 105 human body tissues, as listed in ICRU Report 46, and elementary substances with Z = 1–40. Total and partial attenuation coefficients for these materials were calculated using the XCOM photon cross section database. The effective x-ray energies used to calculate the attenuation were chosen to imitate a dual-source CT scanner operated at 80–140 kV/Sn under well-calibrated and poorly calibrated conditions. Results: The accuracy of the resultant calibrated electron density,ρ{sub e}{sup cal}, for the ICRU-46 body tissues fully satisfied the IPEM-81 tolerance levels in radiotherapy treatment planning. If a criterion of ρ{sub e}{sup cal}/ρ{sub e} − 1 is assumed to be within ±2%, the predicted upper limit of Z applicable for the ΔHU–ρ{sub e} conversion under the well-calibrated condition is Z = 27. In the case of the poorly calibrated condition, the upper limit of Z is approximately 16. The deviation from the ΔHU–ρ{sub e} linearity for higher Z substances is mainly caused by the anomalous variation in the photoelectric-absorption component. Conclusions: Compensation among the three partial components of the photon interactions provides for sufficient linearity of the ΔHU–ρ{sub e} conversion to be applicable for most human tissues even for poorly conditioned scans in which there exists a large variation of effective x

  11. Drop Weight Device Fabrication and Tests for a Dynamic Material Property of Shock-Absorbing Material and Structure in Transportation Package

    A radioactive material transportation package consists of canister and impact limiters. IAEA Safety Standard Series No. TS-R-1 recommends a drop test to evaluate the structural integrity of a transportation package under a hypothetical accident condition. The free drop test of a transportation package from 9 m height simulates one of accident conditions. The transportation package has a potential energy corresponding to 9 m drop height, and this energy changes to a kinetic energy when it impacts on the target. The energy is absorbed by a deformation of shock-absorbing material so that the minimum energy is transferred to canister. Accordingly, the shock-absorbing material is a very important part in transportation package design. Since the data for shock-absorbing material characteristics is acquired by a static test in general, it is quite different to that of dynamic characteristics. And the dynamic characteristics data is hardly found in literature. In this study, a drop weight facility was designed and fabricated which produces an impact speed like that of free drop of 9 m height. Several materials considered for an impact limiter and impact limiter structures were tested by a drop weight facility to acquire a dynamic material characteristics data

  12. Damage analysis of ceramic boron absorber materials in boiling water reactors and initial model for an optimum control rod management

    Operating experience has proved so far that BWR control rods cannot be used for the total reactor life time as originally presumed, but instead has to be considered as a consumable article. After only few operating cycles, the mechanism of absorber failure has been shown to be neutron induced boron carbide swelling and stress cracking of the absorber tubes, followed by erosion of the absorber material. In the case that operation of such a control rod is continued in control cells, this can lead to an increase of the local power density distribution in the core and, under certain conditions, can even cause fuel rod damage. A non destructive testing method has been developed called 'UNDERWATER NEUTRON RADIOGRAPHY' applicable for any BWR control rod. 'Lead-control rods' being radiographed are used to evaluate their actual nuclear worth by the help of a special analytical procedure developed and verified by the author. Nuclear worth data plotted against bum up history data will allow to create an 'EMPIRIC MODEL'. This model includes the basic idea of operating control rods of a certain design first in a control position up to a target fluence limited to an amount just below the appearance of control rod washout. Afterwards they have to be moved in a shut down position to work therefor the total remaining holding period. The initial model is applicable to any CR-design as long as sufficient measuring-data and thus data about the nuclear worth are available. The results of these experiences are extrapolated to the whole reactor holding period. After modelling no further measurements of this particular control rod type are necessary in any reactor. The second focal point is to provide an APPROXIMATION EQUATION. By knowing the absorber radius, B4C density and absorber enclosure data an engineer will calculate reliably the working life of any control rod design on control position. indicated as maximum allowable neutron fluence margin until absorber wash-out starts. This

  13. Relative level excitation in ion-atom collisions as a function of the orbital angular momentum quantum number

    In a previous study of projectile Rydberg state excitations in the collisions Be+, Mg+-He at 10-75 keV it was found, for a fixed value of the principal quantum number n, that the ratio of the s, p, and d level cross sections was close to 1:3:5, whereas the f and g level cross sections drop to approximately the same value as for s levels. Blaney and Berry (1976) found essentially the same increase in cross section for electron transfer into excited Li I states in the Li+-H2 collision. In contrast to this behavior, beam-foil excitations oscillate as a function of the orbital angular momentum quantum number with maxima at odd values of l (p, f,...) and minima at even l (s, d, g,...). Since no model is available to describe these features, the measurements have been extended to other systems to test their general validity. A large conjugated molecule (benzene) was chosen as target gas in one experiment to bridge the gap between ion-atom and ion-foil excitations. The data presented here have all been obtained by optical spectrometry. A quasi molecular approach is used to explain the results. (Auth.)

  14. Determination of total mass attenuation coefficients, effective atomic numbers and electron densities for different shielding materials used in radiation protection

    Almeida J, A. T. [FUNDACENTRO, Centro Regional de Minas Gerais, Brazilian Institute for Safety and Health at Work, Belo Horizonte, 30180-100 Minas Gerais (Brazil); Nogueira, M. S. [Center of Development of Nuclear Technology / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Santos, M. A. P., E-mail: mnogue@cdtn.br [Regional Center for Nuclear Science / CNEN, 50.740-540 Recife, Pernambuco (Brazil)

    2015-10-15

    Full text: In this paper, the interaction of X-rays with some shielding materials has been studied for materials containing different amounts of barite and aggregates. The total mass attenuation coefficient (μ{sub t}) for three shielding materials has been calculated by using WinXCOM program in the energy range from RQR qualities (RQR-4, RQR-6, RQR-9, and RQR-10). They were: cream barite (density 2.99 g/cm{sup 3} collected in the State of Sao Paulo), purple barite (density 2.95 g/cm{sup 3} collected in the State of Bahia) and white barite (density 3.10 g/cm{sup 3} collected in the State of Paraiba). The chemical analysis was carried out by an X-ray fluorescence spectrometer model EDX-720, through dispersive energy. The six elements of the higher concentration found in the sample and analyzed by Spectrophotometry of Energy Dispersive X-ray for the samples were Ba(60.9% - white barite), Ca(17,92% - cream barite), Ce(3,60% - white barite), Fe(17,16% - purple barite), S(12,11% - white barite) and Si(29,61% - purple barite). Also, the effective atomic number (Z{sub eff}) and the effective electron density (N{sub eff}) were calculated using the values of the total mass attenuation coefficient. The dependence of these parameters on the incident photon energy and the chemical composition has been examined. (Author)

  15. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays in 5-MA Saturn discharges is reported. The timing of multiple implosions and the thermal x-ray spectra (1 to 10 keV) agree with 2D radiation-hydrocode simulations. Nonthermal x-ray emission (10 to 100 keV) correlates with pinch spots distributed along the z-axis. The similarities of the measured nonthermal spectrum, yield, and pinch-spot emission with those of 0.8-MA, single-exploded-wire discharges on Gamble-II suggest a common nonthermal-production mechanism. Nonthermal x-ray yields are lower than expected from current scaling of Gamble II results, suggesting that implosion geometries are not as efficient as single-wire geometries for nonthermal x-ray production. The instabilities, azimuthal asymmetries, and inferred multiple implosions that accompany the implosion geometry lead to larger, more irregular pinch spots, a likely reason for reduced nonthermal efficiency. A model for nonthermal-electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas combined with 1D hydrocode simulations of Saturn compact loads predicts weak nonthermal x-ray emission. (author). 3 figs., 10 refs

  16. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays in 5-MA Saturn discharges is reported. The timing of multiple implosions and the thermal x-ray spectra (1 to 10 keV) agree with 2D radiation-hydrocode simulations. Nonthermal x-ray emission (10 to 100 keV) correlates with pinch spots distributed along the z-axis. The similarities of the measured nonthermal spectrum, yield, and pinch-spot emission with those of 0.8-MA, single- exploded-wire discharges on Gamble-II suggest a common nonthermal- production mechanism. Nonthermal x-ray yields are lower than expected from current scaling of Gamble II results, suggesting that implosion geometries are not as efficient as single-wire geometries for nonthermal x-ray production. The instabilities, azimuthal asymmetries, and inferred multiple implosions that accompany the implosion geometry lead to larger, more irregular pinch spots, a likely reason for reduced nonthermal efficiency. A model for nonthermal-electron acceleration across magnetic fields in highly- collisional, high-atomic-number plasmas combined with 1D hydrocode simulations of Saturn compact loads predicts weak nonthermal x-ray emission

  17. Determination of total mass attenuation coefficients, effective atomic numbers and electron densities for different shielding materials used in radiation protection

    Full text: In this paper, the interaction of X-rays with some shielding materials has been studied for materials containing different amounts of barite and aggregates. The total mass attenuation coefficient (μt) for three shielding materials has been calculated by using WinXCOM program in the energy range from RQR qualities (RQR-4, RQR-6, RQR-9, and RQR-10). They were: cream barite (density 2.99 g/cm3 collected in the State of Sao Paulo), purple barite (density 2.95 g/cm3 collected in the State of Bahia) and white barite (density 3.10 g/cm3 collected in the State of Paraiba). The chemical analysis was carried out by an X-ray fluorescence spectrometer model EDX-720, through dispersive energy. The six elements of the higher concentration found in the sample and analyzed by Spectrophotometry of Energy Dispersive X-ray for the samples were Ba(60.9% - white barite), Ca(17,92% - cream barite), Ce(3,60% - white barite), Fe(17,16% - purple barite), S(12,11% - white barite) and Si(29,61% - purple barite). Also, the effective atomic number (Zeff) and the effective electron density (Neff) were calculated using the values of the total mass attenuation coefficient. The dependence of these parameters on the incident photon energy and the chemical composition has been examined. (Author)

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

    Singh Vishwanath P.

    2012-01-01

    Full Text Available Total mass attenuation coefficients, µm, 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.

  19. On the effective atomic number and electron density: A comprehensive set of formulas for all types of materials and energies above 1 keV

    Manohara, S.R.; Hanagodimath, S.M.; Thind, K.S.;

    2008-01-01

    A comprehensive and consistent set of formulas is given for calculating the effective atomic number and electron density for all types of materials and for all photon energies greater than 1 keV. The are derived from first principles using photon interaction cross sections of the constituent atoms....... The theory is illustrated by calculations and experiments for molecules of medical and biological interest, glasses for radiation shielding, alloys, minerals and liquids....

  20. Research Progress in Cellulose-based Absorbent Material%纤维素系吸水材料的研究现状及发展前景

    高桂林; 沈葵忠; 房桂干; 邓拥军; 李萍; 金莉; 别士霞

    2012-01-01

    This review addressed recent progress in cellulose-based absorbent materials preparation and application Firstly, absorbent material produced directly from native cellulose (including bacterial cellulose) via cellulose dissolution are introduced. Secondly, cellulose highly absorbing polymer based on its derivatives which were obtained by physical as well as chemical cross-linking strategies was discussed. Thirdly, composite prepared by using cellulose in conjunction with other polymers through blending, formation of polyelectrolyte complexes, and interpenetrating polymer networks (IPNs) technology was addressed . Finally, cellulose-inorganic hybrid hydrogel prepared by embedding inorganic nano-partieles in cellulose matrices was described. In addition,the prospect of cellulosic absorbent materials and some problems still needed to be solved were summarized.%本文回顾了近年来纤维素系吸水材料的制备方法及其应用,具体介绍了纤维素系吸水材料的几种主要制备方法:一是直接对天然纤维素进行处理来制备;第二是利用纤维素衍生物通过物理或化学交联的方法制备;第三是将纤维素与其他聚合物进行反应形成复合树脂或聚电解质配合物,还可以采用互穿聚合网络技术进行处理;另外将无机纳米粒子嵌入纤维素矩阵中也可以制备纤维素-无机混合凝胶树脂。最后还对纤维素系高吸水材料的发展前景以及仍需解决的问题进行了总结。

  1. Influence of Secondary Phases in Kesterite-Cu2ZnSnS4 Absorber Material Based on the First Principles Calculation

    Wujisiguleng Bao; Masaya Ichimura

    2015-01-01

    The influence of secondary phases of ZnS and Cu2SnS3 (CTS) in Cu2ZnSnS4 (CZTS) absorber material has been studied by calculating the band offsets at the CTS/CZTS/ZnS multilayer heterojunction interfaces on the basis of the first principles band structure calculation. The ZnS/CZTS heterointerface is of type I and since ZnS has a larger band gap than that of CZTS, the ZnS phase in CZTS is predicted to be resistive barriers for carriers. The CTS/CZTS heterointerface is of type I; that is, the ba...

  2. X-ray emission from a high-atomic-number z-pinch plasma created from compact wire arrays

    Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays, driven by 5 MA from the Saturn accelerator, are measured and compared with LLNL Radiation-Hydro-Code (RHC) and SNL Hydro-Code (HC) numerical models. Multiple implosions, due to sequential compressions and expansions of the plasma, are inferred from the measured multiple x-radiation bursts. Timing of the multiple implosions and the thermal x-ray spectra measured between 1 and 10 keV are consistent with the RHC simulations. The magnitude of the nonthermal x-ray emission measured from 10 to 100 keV ranges from 0.02 to 0.08% of the total energy radiated and is correlated with bright-spot emission along the z-axis, as observed in earlier Gamble-11 single exploding-wire experiments. The similarities of the measured nonthermal spectrum and bright-spot emission with those measured at 0.8 MA on Gamble-II suggest a common production mechanism for this process. A model of electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas is developed, which shows the existence of a critical electric field, Ec, below which strong nonthermal electron creation (and the associated nonthermal x rays) do not occur. HC simulations show that significant nonthermal electrons are not expected in this experiment (as observed) because the calculated electric fields are at least one to two orders-of-magnitude below Ec. These negative nonthermal results are confirmed by RHC simulations using a nonthermal model based on a Fokker-Plank analysis. Lastly, the lower production efficiency and the larger, more irregular pinch spots formed in this experiment relative to those measured on Gamble II suggest that implosion geometries are not as efficient as single exploding-wire geometries for warm x-ray production

  3. Study of effective atomic numbers and electron densities, kerma of alcohols, phantom and human organs, and tissues substitutes

    Singh Vishwanath P.

    2013-01-01

    Full Text Available Effective atomic numbers (ZPIeff and electron densities of eighteen alcohols such as wood alcohol, CH3OH; grain alcohol, C2H5OH; rubbing alcohol, C3H7OH; butanol, C4H9OH; amyl alcohol, C5H11OH; cetyl alcohol, C16H33OH; ethylene glycol, C2H4(OH2; glycerin, C3H5(OH3; PVA, C2H4O; erythritol, C4H6(OH4; xylitol, C5H7(OH5; sorbitol, C6H8(OH6; volemitol, C7H9(OH7; allyl alcohol, C3H5OH; geraniol, C10H17OH; propargyl alcohol, C3H3OH; inositol, C6H6(OH6, and menthol, C10H19OH have been calculated in the photon energy region of 1 keV-100 GeV. The estimated values have been compared with experimental values wherever possible. The comparison of ZPIeff of the alcohols with water phantom and PMMA phantom indicate that the ethylene glycol, glycerin, and PVA are substitute for PMMA phantom and PVA is substitute of water phantom. ZPIeff of alcohols have also been compared with human organs and tissues. Ethylene glycol, glycerin and PVA, allyl alcohol, and wood alcohols are found tissue substitutes for most of human organs. Kerma which is the product of the energy fluence and mass energy-absorption coefficient, have been calculated in the energy region from 1 keV to 20 MeV for the alcohols. The results show the kerma is more or less independent of energy above 100 keV.

  4. Structural properties of the titanium dioxide thin films grown by atomic layer deposition at various numbers of reaction cycles

    A dependence of structural properties of TiO2 films grown on both Si- and Ti-substrates by atomic layer deposition (ALD) at the temperature range of 250-300 deg. C from titanium ethoxide and water on the number of reaction cycles N was investigated using Fourier-transform infrared (FTIR) spectroscopy and X-Ray diffraction (XRD). TiO2 films grown on both Si- and Ti-substrates revealed amorphous structure at low values of N 2 with structure of anatase on both types of substrates and according to XRD-measurements the sizes of crystallites rose with the increase of N. The maximum anatase crystallite size for TiO2 grown on Ti-substrate was found to be on ∼35% lower in comparing with that for TiO2 grown on Si-substrate. A use of titanium methoxide as a Ti precursor with the ligand size smaller than in case of titanium ethoxide allowed to observe an influence of the ligand size on both the growth per cycle and structural properties of TiO2. The average growth per cycle of TiO2 deposited from titanium methoxide and water (0.052 ± 0.01 nm/cycle) was essentially higher than that for TiO2 grown from titanium ethoxide and water (0.043 ± 0.01 nm/cycle). Ligands of smaller sizes were found to promote the higher crystallinity of TiO2 in comparison with the case of using the titanium precursor with ligands of bigger sizes.

  5. Deriving effective atomic numbers from DECT based on a parameterization of the ratio of high and low linear attenuation coefficients

    Landry, Guillaume; Seco, Joao; Gaudreault, Mathieu; Verhaegen, Frank

    2013-10-01

    Dual energy computed tomography (DECT) can provide simultaneous estimation of relative electron density ρe and effective atomic number Zeff. The ability to obtain these quantities (ρe, Zeff) has been shown to benefit selected radiotherapy applications where tissue characterization is required. The conventional analysis method (spectral method) relies on knowledge of the CT scanner photon spectra which may be difficult to obtain accurately. Furthermore an approximate empirical attenuation correction of the photon spectrum through the patient is necessary. We present an alternative approach based on a parameterization of the measured ratio of low and high kVp linear attenuation coefficients for deriving Zeff which does not require the estimation of the CT scanner spectra. In a first approach, the tissue substitute method (TSM), the Rutherford parameterization of the linear attenuation coefficients was employed to derive a relation between Zeff and the ratio of the linear attenuation coefficients measured at the low and high kVp of the CT scanner. A phantom containing 16 tissue mimicking inserts was scanned with a dual source DECT scanner at 80 and 140 kVp. The data from the 16 inserts phantom was used to obtain model parameters for the relation between Zeff and \\mu \\big|_{140kVp}^{80kVp}. The accuracy of the method was evaluated with a second phantom containing 4 tissue mimicking inserts. The TSM was compared to a more complex approach, the reference tissue method (RTM), which requires the derivation of stoichiometric fit parameters. These were derived from the 16 inserts phantom scans and used to calculate CT numbers at 80 and 140 kVp for a set of tabulated reference human tissues. Model parameters for the parameterization of \\mu \\big|_{140\\;kVp}^{80\\;kVp} were estimated for this reference tissue dataset and compared to the results of the TSM. Residuals on Zeff for the reference tissue dataset for both TSM and RTM were compared to those obtained from the

  6. Microwave Absorption Properties of Double-Layer RADAR Absorbing Materials Based on Doped Barium Hexaferrite/TiO2/Conducting Carbon Black

    Sukanta Das

    2014-01-01

    Full Text Available In this report, we demonstrate microwave absorption properties of barium hexaferrite, doped barium hexaferrite, titanium dioxide and conducting carbon black based RADAR absorbing material for stealth application. Double-layer absorbers are prepared with a top layer consisting of 30% hexaferrite and 10% titanium dioxide while the bottom layer composed of 30% hexaferrite and 10% conducting carbon black, embedded in chloroprene matrix. The top and bottom layers are prepared as impedance matching layer and conducting layer, respectively, with a total thickness of 2 mm. Microwave absorption properties of all the composites were analyzed in X-band region. Maximum reflection loss of −32 dB at 10.64 GHz was observed for barium hexaferrite based double-layer absorber whereas for doped barium hexaferrite based absorber the reflection loss was found to be −29.56 dB at 11.7 GHz. A consistence reflection loss value (>−24 dB was observed for doped barium hexaferrite based RADAR absorbing materials within the entire bandwidth.

  7. Characterization and MCNP simulation of neutron energy spectrum shift after transmission through strong absorbing materials and its impact on tomography reconstructed image

    An ideal neutron radiograph, for quantification and 3D tomographic image reconstruction, should be a transmission image which exactly obeys to the exponential attenuation law of a monochromatic neutron beam. There are many reasons for which this assumption does not hold for high neutron absorbing materials. The main deviations from the ideal are due essentially to neutron beam hardening effect. The main challenges of this work are the characterization of neutron transmission through boron enriched steel materials and the observation of beam hardening. Then, in our work, the influence of beam hardening effect on neutron tomographic image, for samples based on these materials, is studied. MCNP and FBP simulation are performed to adjust linear attenuation coefficients data and to perform 2D tomographic image reconstruction with and without beam hardening corrections. A beam hardening correction procedure is developed and applied based on qualitative and quantitative analyses of the projections data. Results from original and corrected 2D reconstructed images obtained shows the efficiency of the proposed correction procedure. - Highlights: ► Characterization of neutron transmission through strong absorbing material. ► Neutron energy spectrum shift study. ► Beam hardening observation and characterization. ► Beam hardening effect on neutron tomography image appearance. ► MCNP and FBP simulation to adjust attenuation coefficients for a correct tomographic reconstruction.

  8. Research Progress of Rare Earth Electromagnetic Wave Absorbing Material%稀土吸波材料的研究进展

    邓智平; 刘朝辉; 周国柱; 张行

    2013-01-01

      吸波材料是一种重要的特种材料,对解决电磁污染、电磁兼容以及提升武器装备的隐身能力起着重要的作用。从吸波材料的应用出发,介绍了稀土增强材料吸波能力的机理,然后分别从稀土元素掺杂铁氧体材料、稀土过渡金属间化合物、稀土锰基氧化物LSMO材料以及稀土掺杂磁性薄膜几方面,对吸波材料中这类重要的稀土吸波材料的研究现状进行了论述。%Electromagnetic wave absorbing material is an important special material, which plays a crucial role in solving the problem of electromagnetic pollution and electromagnetic compatibility, and enhancing the stealth ability of weapons. Based on the application of electromagnetic wave absorbing material, the rare earth element doped ferrite, rare earth transitionmetal intermetallic compounds, rare earth manganese oxides LSMO materials, and rare-earth doped magnetic film were introduced.

  9. Enhancement in the number of trapped atoms in a cesium magneto-optical trap by a near-resonant control laser

    We demonstrate enhancement in the number of trapped cesium atoms in a magneto-optical trap (MOT) using a control laser that illuminates only a small faction of the capture region of the trap without interacting with the cold cloud of atoms. The enhancement is maximized when the laser is slightly blue detuned with respect to the cooling transition. Trap loading curves point to approximately a twofold increase in the capture rate, which as a consequence results in the increase in the steady state number of trapped atoms. Enhanced loading is confirmed by MOT loading and decay curves taken under the modulation of the control laser beam. Optical pumping of the inaccessible Zeeman states into the stretched states is suggested as a possible mechanism

  10. Development of a standard data base for FBR core nuclear design. 10. Reevaluation of atomic number density of JOYO Mk-II core

    The material composition of JOYO Mk-II core components in its initial core was reevaluated as a part of the effort for developing a standard data base for FBR core nuclear design. The special feature of the reevaluation is to treat the decay of Pu-241 isotope, so that the atomic number densities of Pu-241 and Am-241 in fuel assemblies can be exactly evaluated on the initial critical date, Nov. 22nd, 1982. Further, the atomic number densities of other core components were also evaluated to improve the analytical accuracy. Those include the control rods which were not so strictly evaluated in the past, and the dummy fuels and the neutron sources which were not treated in the analytical model so far. The results of the present reevaluation were as follows: (1) The changes of atomic number densities of the major nuclides such as Pu-239, U-235 and U-238 were about ±0.2 to 0.3%. On the other hand, the number density of Pu-241, which was the motivation of the present work, was reduced by 12%. From the fact, the number densities in the past analysis might be based on the isotope measurement of the manufacturing point of time without considering the decay of Pu-241. (2) As the other core components, the number densities of control rods and outer reflector-type A were largely improved. (author)

  11. Development of a standard data base for FBR core nuclear design. 10. Reevaluation of atomic number density of JOYO Mk-II core

    Numata, Kazuyuki; Sato, Wakaei [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center; Ishikawa, Makoto; Arii, Yoshio [Nuclear Energy System Incorporation, Tokyo (Japan)

    1999-07-01

    The material composition of JOYO Mk-II core components in its initial core was reevaluated as a part of the effort for developing a standard data base for FBR core nuclear design. The special feature of the reevaluation is to treat the decay of Pu-241 isotope, so that the atomic number densities of Pu-241 and Am-241 in fuel assemblies can be exactly evaluated on the initial critical date, Nov. 22nd, 1982. Further, the atomic number densities of other core components were also evaluated to improve the analytical accuracy. Those include the control rods which were not so strictly evaluated in the past, and the dummy fuels and the neutron sources which were not treated in the analytical model so far. The results of the present reevaluation were as follows: (1) The changes of atomic number densities of the major nuclides such as Pu-239, U-235 and U-238 were about {+-}0.2 to 0.3%. On the other hand, the number density of Pu-241, which was the motivation of the present work, was reduced by 12%. From the fact, the number densities in the past analysis might be based on the isotope measurement of the manufacturing point of time without considering the decay of Pu-241. (2) As the other core components, the number densities of control rods and outer reflector-type A were largely improved. (author)

  12. Deriving effective atomic numbers from DECT based on a parameterization of the ratio of high and low linear attenuation coefficients

    Dual energy computed tomography (DECT) can provide simultaneous estimation of relative electron density ρe and effective atomic number Zeff. The ability to obtain these quantities (ρe, Zeff) has been shown to benefit selected radiotherapy applications where tissue characterization is required. The conventional analysis method (spectral method) relies on knowledge of the CT scanner photon spectra which may be difficult to obtain accurately. Furthermore an approximate empirical attenuation correction of the photon spectrum through the patient is necessary. We present an alternative approach based on a parameterization of the measured ratio of low and high kVp linear attenuation coefficients for deriving Zeff which does not require the estimation of the CT scanner spectra. In a first approach, the tissue substitute method (TSM), the Rutherford parameterization of the linear attenuation coefficients was employed to derive a relation between Zeff and the ratio of the linear attenuation coefficients measured at the low and high kVp of the CT scanner. A phantom containing 16 tissue mimicking inserts was scanned with a dual source DECT scanner at 80 and 140 kVp. The data from the 16 inserts phantom was used to obtain model parameters for the relation between Zeff and μ|(80kVp)/140kVp. The accuracy of the method was evaluated with a second phantom containing 4 tissue mimicking inserts. The TSM was compared to a more complex approach, the reference tissue method (RTM), which requires the derivation of stoichiometric fit parameters. These were derived from the 16 inserts phantom scans and used to calculate CT numbers at 80 and 140 kVp for a set of tabulated reference human tissues. Model parameters for the parameterization of μ|(80kVp)/140kVp were estimated for this reference tissue dataset and compared to the results of the TSM. Residuals on Zeff for the reference tissue dataset for both TSM and RTM were compared to those obtained from the spectral method. The tissue

  13. Fidelity of quantum information for Ⅴ-type three-level atom interacting with a number state light field in Kerr medium

    Liu Su-Mei; He An-Zhi; Ji Yun-Jing

    2008-01-01

    In this paper the evolution characteristics of the fidelity of quantum information for the Ⅴ-type three-level atom interacting with number state light field in Kerr medium are investigated. It shows that the periodicity of the evolutions of fidelity of quantum information is influenced by the Kerr coefficient, the photon number of the initial field and intensity of light. The evolutions of the fidelity of quantum information are modulated by the initial number state field. The Rabi oscillation frequency and the modulation frequency of fidelity for the field and the system vary with the value of the Kerr coefficient. The evolutions of fidelity of quantum information obviously show the quantum collapse and revival behaviours in the system of atom interacting with light field.

  14. The Mass Attenuation Coefficients, Electronic, Atomic, and Molecular Cross Sections, Effective Atomic Numbers, and Electron Densities for Compounds of Some Biomedically Important Elements at 59.5 keV

    Burcu Akça; Erzeneoğlu, Salih Z.

    2014-01-01

    The mass attenuation coefficients for compounds of biomedically important some elements (Na, Mg, Al, Ca, and Fe) have been measured by using an extremely narrow collimated-beam transmission method in the energy 59.5 keV. Total electronic, atomic, and molecular cross sections, effective atomic numbers, and electron densities have been obtained by using these results. Gamma-rays of 241Am passed through compounds have been detected by a high-resolution Si(Li) detector and by using energy dispers...

  15. Influence of Secondary Phases in Kesterite-Cu2ZnSnS4 Absorber Material Based on the First Principles Calculation

    Wujisiguleng Bao

    2015-01-01

    Full Text Available The influence of secondary phases of ZnS and Cu2SnS3 (CTS in Cu2ZnSnS4 (CZTS absorber material has been studied by calculating the band offsets at the CTS/CZTS/ZnS multilayer heterojunction interfaces on the basis of the first principles band structure calculation. The ZnS/CZTS heterointerface is of type I and since ZnS has a larger band gap than that of CZTS, the ZnS phase in CZTS is predicted to be resistive barriers for carriers. The CTS/CZTS heterointerface is of type I; that is, the band gap of CTS is located within the band gap of CZTS. Therefore, the CTS phase will act as a recombination site in CZTS.

  16. The Investigation on the Potential of Coconut Shell Powder Composite in Term of Carbon Composition, Surface Porosity and Dielectric Properties as a Microwave Absorbing Material

    Yew Been Seok

    2016-01-01

    Full Text Available Agricultural wastes are renewable resources that are potentially useful as microwave absorbing materials. This paper presents the investigation on the carbon composition, surface porosity of the raw coconut shell powder particles and the dielectric properties of coconut shell powder with epoxy resin matrix composites. From CHNS elemental analysis, it was found that the carbon composition of coconut shell powder is 46.700%. Presences of macropores (≈ 2μm were detected in the SEM analysis of the coconut shell powder particles. Measurement on dielectric properties of the coconut shell powder composites was performed by using open-ended coaxial probe method over microwave frequency range of 1-8 GHz. The overall dielectric constant (εr’ and dielectric loss factor (εr” of the composite with ratio 50:50 were 3.56 and 0.26, ranging from 3.35-3.76 and 0.21-0.30 respectively; whereas for composite ratio 40:60, the overall dielectric constant (εr’ and dielectric loss factor (εr” were 2.97 and 0.21, ranging from 2.74-3.17 and 0.16-0.27 respectively. The electrical conductivity calculated based on measured εr” was 0.067 and 0.054 for composite ratio 50:50 and 40:60 respectively. The dielectric properties and electrical conductivity of the coconut shell powder composites were influenced by the greater presence of high dielectric material (coconut shell powder. This experimental investigation on the potential of the coconut shell powder with epoxy resin composites indicates that the ability of the composite to absorb and convert microwave signals is dependent on the carbonaceous materials of the composite. This result offers a great opportunity to diversify the use of coconut shell powder as microwave absorbing material.

  17. Development of basket for transport/storage cask using square tube made of aluminium alloy containing neutron absorbing materials

    The basket of transport/storage cask must have a structural strength at any temperature expected during storage and transport condition, and must satisfy each function of sub-criticality and heat removal. It is also preferable to increase the number of fuel assemblies in the cask and to reduce the manufacturing cost. The use of aluminium alloy for the basket is preferable because of its high thermal conductivity in order to improve heat removal. Aluminium alloy is lightweight and it is more effective to improve the capacity. The conventional design of aluminium basket had a combination of square tubes, which have structural strength and heat removal function, and the neutron absorption material with high concentration of boron. The developed basket has square tube shape containing neutron absorption materials that has both functions of heat removal and sub-criticality. It is an effective way to improve the storage capacity of fuel assemblies and it is also easy to be assembled

  18. A simple model for the size and shape dependent Curie temperature of freestanding Ni and Fe nanoparticles based on the average coordination number and atomic cohesive energy

    Graphical abstract: To study the effect of size and shape of metallic nanoparticle on their Curie temperature of FCC (Fig. A) and BCC clusters (Fig. B), an analytical model is proposed. When variable core coordination number is utilised, a low Curie temperature is observed at a critical cluster size of 2-3 nm in good agreement with experimental results. This critical diameter corresponds to the 50% fractional surface atoms. Display Omitted Highlights: → The Curie temperature (TC) of freestanding Ni and Fe nanoparticles have been examined. → The average coordination number as a geometrical parameter has been considered. → It is found that for even smaller particles, the Curie temperature actually increases. - Abstract: To study the effect of size and shape of metallic nanoparticle on their Curie temperature, an analytical model is proposed. The core average coordination number (CAC) and surface average coordination number (SAC) of freestanding nanoparticles are considered in the model. Clusters of icosahedral (IC) and body centred cubic (BCC) structure without any vacancies and defects are modelled. A critical Curie temperature is introduced for metallic clusters with a diameter of 2-3 nm. This critical diameter is related to clusters which the ratio of surface atoms to total atoms is about 50%. The 'shape effect' is shown to be important at sizes less than 20 nm. The obtained results are supported by available experimental results for nickel and iron nanoparticles.

  19. Spatial distribution of the temperature and the number densities of electrons and atomic and ionic species in an inductively coupled RF argon plasma, ch. 3

    A survey of the literature shows that the values found for the excitation parameters (temperature and electron number density) in an inductively coupled radio-frequency argon plasma at atmospheric pressure (ICP) depend on the plasma configuration and the measuring procedure. The present study proposes a novel method for measuring excitation temperatures that does not require a knowledge of transition probabilities. The experimental work concerns measurements of the spatial distributions of the temperature, the number densities of the electrons and various atomic and ionic species in a low-power (approximately o.5kW) ICP for analytical purposes operated at either of two extreme carrier gas flow rates. Observations were made at three different heights above the induction coil. At high flow rate (approximately 51/min) the familiar hollow configuration of the plasma is demonstrated by off-axis maxima for the temperature and the number densities of electrons and atomic species at all observation heights. At low flow rate (approximately 1 l./min), the radial atom number density distributions are parabolically shaped and constricted to a smaller channel at all observation heights. The authors conclude from the results that both the plasma configurations are not in a state of complete local thermal equilibrium at observation heights used for analytical work (i.e., above the coil)

  20. Comparison of Martian meteorites with earth composition: Study of effective atomic numbers in the energy range 1 keV-100 GeV

    Ün, Adem; Han, Ibrahim; Ün, Mümine

    2016-04-01

    Effective atomic (Zeff) and electron numbers (Neff) for 24 Martian meteorites have been determined in the energy range from 1 keV to 100 GeV and also for sixteen significant energies of commonly used radioactive sources. The values of Zeff and Neff for all sample were obtained from the DirectZeff program. The obtained results for Martian meteorites have been compared with the results for Earth composition and similarities or differences also evaluated.

  1. Effective atomic numbers of some H-, C-, N- and O-based composite materials derived from differential incoherent scattering cross-sections

    S Prasanna Kumar; V Manjunathaguru; T K Umesh

    2010-04-01

    In this work, we have made an effort to determine whether the effective atomic numbers of H-, C-, N- and O-based composite materials would indeed remain a constant over the energy grid of 280–1200 keV wherein incoherent scattering dominates their interaction with photons. For this purpose, the differential incoherent scattering cross-sections of Be, C, Mg, Al, Ca and Ti were measured for three scattering angles 60°, 80° and 100° at 279.1, 661.6 and 1115.5 keV using which an expression for the effective atomic number was derived. The differential incoherent scattering cross-sections of the composite materials of interest measured at these three angles in the same set-up and substituted in this expression would yield their effective atomic number at the three energies. Results obtained in this manner for bakelite, nylon, epoxy, teflon, perspex and some sugars, fatty acids as well as amino acids agreed to within 2% of some of the other available values. It was also observed that for each of these samples, eff was almost a constant at the three energies which unambiguously justified the conclusions drawn by other authors earlier [Manjunathaguru and Umesh, J. Phys. B: At. Mol. Opt. Phys. 39, 3969 (2006); Manohara et al, Nucl. Instrum. Methods B266, 3906 (2008); Manohara et al Phys. Med. Biol. 53, M377 (2008)] based on total interaction cross-sections in the energy grid of interest.

  2. Studies on mass attenuation coefficient, effective atomic number and electron density of some amino acids in the energy range 0.122-1.330 MeV

    Pawar, Pravina P.; Bichile, Govind K.

    2013-11-01

    The total mass attenuation coefficients of some amino acids, such as Glycine (C2H5NO2), DL-Alanine (C3H7NO2), Proline (C5H9NO2), L-Leucine (C6H13NO2 ), L-Arginine (C6H14N4O2) and L-Arginine Monohydrochloride (C6H15ClN4O2), were measured at 122, 356, 511, 662, 1170, 1275 and 1330 keV photon energies using a well-collimated narrow beam good geometry set-up. The gamma rays were detected using NaI (Tl) scintillation detection system with a resolution of 10.2% at 662 keV. The attenuation coefficient data were then used to obtain the effective atomic numbers (Zeff) and effective electron densities (Neff) of amino acids. It was observed that the effective atomic number (Zeff) and effective electron densities (Neff) tend to be almost constant as a function of gamma-ray energy. The results show that, the experimental values of mass attenuation coefficients, effective atomic numbers and effective electron densities are in good agreement with the theoretical values with less than 1% error.

  3. Raman and ellipsometry spectroscopic analysis of graphene films grown directly on Si substrate via CVD technique for estimating the graphene atomic planes number

    Al-Hazmi, F. S.; Beall, Gary W.; Al-Ghamdi, A. A.; Alshahrie, Ahmed; Shokr, F. S.; Mahmoud, Waleed E.

    2016-08-01

    Two reliable approaches for estimating the number of atomic planes of graphene films grown on Si substrate were demonstrated by Raman and ellipsometry spectroscopies. The first approach depends on the measurement of the ratio of the integrated Raman scattering intensity of the graphene G band to the optical phonon band of Si substrate (IG/ISi). The second approach belongs to ellipsometry measurement of the ratio of the amplitude of the reflected polarized light from the surface of the graphene films to the amplitude of reflected polarized light from the surface of the Si substrate (ΨG/ΨSi). These two approaches could efficiently recognize the number of atomic planes in the graphene films (1 ≤ n ≤ 10). The results were compared with atomic force microscopy (AFM) measurement and showed a linear regression with slope of 0.36 ± 0.01 nm/graphene layer. The Two approaches will open a new avenue to efficiently count the number of graphene layers during the preparation process.

  4. Studies on effective atomic numbers and electron densities in amino acids and sugars in the energy range 30-1333 keV

    The effective atomic numbers and electron densities of the amino acids glycine, alanine, serine, valine, threonine, leucine, isoleucine, aspartic acid, lysine, glutamic acid, histidine, phenylalanine, arginine, tyrosine, tryptophane and the sugars arabinose, ribose, glucose, galactose, mannose, fructose, rhamnose, maltose, melibiose, melezitose and raffinose at the energies 30.8, 35.0, 81.0, 145, 276.4, 302.9, 356, 383.9, 661.6, 1173 and 1332.5 keV were calculated by using the measured total attenuation cross-sections. The interpolations of total attenuation cross-sections for photons of energy E in elements of atomic number Z was performed using the logarithmic regression analysis of the XCOM data in the photon energy region 30-1500 keV. The best-fit coefficients obtained by a piece wise interpolation method were used to find the effective atomic number and electron density of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data

  5. Electron density and transport in top-gated graphene nanoribbon devices: First-principles Green function algorithms for systems containing a large number of atoms

    Areshkin, Denis A.; Nikolić, Branislav K.

    2010-04-01

    The recent fabrication of graphene nanoribbon (GNR) field-effect transistors poses a challenge for first-principles modeling of carbon nanoelectronics due to many thousand atoms present in the device. The state of the art quantum transport algorithms, based on the nonequilibrium Green function formalism combined with the density-functional theory (NEGF-DFT), were originally developed to calculate self-consistent electron density in equilibrium and at finite bias voltage (as a prerequisite to obtain conductance or current-voltage characteristics, respectively) for small molecules attached to metallic electrodes where only a few hundred atoms are typically simulated. Here we introduce combination of two numerically efficient algorithms which make it possible to extend the NEGF-DFT framework to device simulations involving large number of atoms. Our first algorithm offers an alternative to the usual evaluation of the equilibrium part of electron density via numerical contour integration of the retarded Green function in the upper complex half-plane. It is based on the replacement of the Fermi function f(E) with an analytic function f˜(E) coinciding with f(E) inside the integration range along the real axis, but decaying exponentially in the upper complex half-plane. Although f˜(E) has infinite number of poles, whose positions and residues are determined analytically, only a finite number of those poles have non-negligible residues. We also discuss how this algorithm can be extended to compute the nonequilibrium contribution to electron density, thereby evading cumbersome real-axis integration (within the bias voltage window) of NEGFs which is very difficult to converge for systems with large number of atoms while maintaining current conservation. Our second algorithm combines the recursive formulas with the geometrical partitioning of an arbitrary multiterminal device into nonuniform segments in order to reduce the computational complexity of the retarded Green

  6. Polarizabilities and van der Waals C6 coefficients of fullerenes from an atomistic electrodynamics model: Anomalous scaling with number of carbon atoms

    Saidi, Wissam A.; Norman, Patrick

    2016-07-01

    The van der Waals C6 coefficients of fullerenes are shown to exhibit an anomalous dependence on the number of carbon atoms N such that C6 ∝ N2.2 as predicted using state-of-the-art quantum mechanical calculations based on fullerenes with small sizes, and N2.75 as predicted using a classical-metallic spherical-shell approximation of the fullerenes. We use an atomistic electrodynamics model where each carbon atom is described by a polarizable object to extend the quantum mechanical calculations to larger fullerenes. The parameters of this model are optimized to describe accurately the static and complex polarizabilities of the fullerenes by fitting against accurate ab initio calculations. This model shows that C6 ∝ N2.8, which is supportive of the classical-metallic spherical-shell approximation. Additionally, we show that the anomalous dependence of the polarizability on N is attributed to the electric charge term, while the dipole-dipole term scales almost linearly with the number of carbon atoms.

  7. Measurement of atomic L shell Coster-Kronig yields (f12, f23 and f13) for some elements in the atomic number range 59≤Z≤90

    Non-radiative transitions cause changes in the generation of the intensity of the L lines. In order to investigate the physical quantities relevant to the L lines affected by the non-radiative transitions, experimental measurements were carried out using a Si(Li) x-ray spectrometer. Atomic L shell Coster-Kronig yields (f12, f13 and f23) for some elements in the atomic number range 59≤Z≤90 were determined. These selected measured semi-empirical values were also fitted by least squares to polynomials in Z of the form ΣnanZn (except for f13) and compared with theoretical and with earlier fitted values. (author)

  8. The Mass Attenuation Coefficients, Electronic, Atomic, and Molecular Cross Sections, Effective Atomic Numbers, and Electron Densities for Compounds of Some Biomedically Important Elements at 59.5 keV

    Burcu Akça

    2014-01-01

    Full Text Available The mass attenuation coefficients for compounds of biomedically important some elements (Na, Mg, Al, Ca, and Fe have been measured by using an extremely narrow collimated-beam transmission method in the energy 59.5 keV. Total electronic, atomic, and molecular cross sections, effective atomic numbers, and electron densities have been obtained by using these results. Gamma-rays of 241Am passed through compounds have been detected by a high-resolution Si(Li detector and by using energy dispersive X-ray fluorescence spectrometer (EDXRF. Obtained results have been compared with theoretically calculated values of WinXCom and FFAST. The relative difference between the experimental and theoretical values are −9.4% to +11.9% with WinXCom and −11.8% to +11.7% FFAST. Results have been presented and discussed in this paper.

  9. 粘土/聚合物复合吸水材料的研究进展%Research Progress of Clay/Polymer Composite Absorbent Materials

    朱林晖; 张丽丽; 丁马太; 杨静

    2011-01-01

    The influence of clay minerals on modification mechanism, modification methods of super-absorbent polymer was reviewed. The main types of current existed clay/polymer composite absorbent materials were introduced in the paper. The analysis showed that the main problem of the composite materials was very difficult to coordinate the relation among three factors, such as absorbent ability, gel strength and salt-resistance. The research direction in future is to compose it with natural resources to develop the eco-friendly products and apply them to remove high toxic dyes and harmful heavy metal ions from industrial wastewater.%综述了粘土矿物对于高吸水性聚合物的改性机理、改性方法的影响,介绍了目前粘土/聚合物复合吸水材料的主要种类。分析指出,吸水能力、凝胶强度与耐盐性三者乏阊难以统筹兼顾是这类复合材料当前存在的主要问题,将其与天然资源复合开发环境友好型产品,并用于废水中高毒染料和有害金属离子的去除是其今后的发展方向。

  10. Measurement and modeling of a diamond deposition reactor: Hydrogen atom and electron number densities in an Ar/H2 arc jet discharge

    A combination of experiment [optical emission and cavity ring-down spectroscopy (CRDS) of electronically excited H atoms] and two-dimensional (2D) modeling has enabled a uniquely detailed characterization of the key properties of the Ar/H2 plasma within a ≤10-kW, twin-nozzle dc arc jet reactor. The modeling provides a detailed description of the initial conditions in the primary torch head and of the subsequent expansion of the plasma into the lower pressure reactor chamber, where it forms a cylindrical plume of activated gas comprising mainly of Ar, Ar+, H, ArH+, and free electrons. Subsequent reactions lead to the formation of H2 and electronically excited atoms, including H(n=2) and H(n=3) that radiate photons, giving the plume its characteristic intense emission. The modeling successfully reproduces the measured spatial distributions of H(n>1) atoms, and their variation with H2 flow rate, FH20. Computed H(n=2) number densities show near-quantitative agreement with CRDS measurements of H(n=2) absorption via the Balmer-β transition, successfully capturing the observed decrease in H(n=2) density with increased FH20. Stark broadening of the Balmer-β transition depends upon the local electron density in close proximity to the H(n=2) atoms. The modeling reveals that, at low FH20, the maxima in the electron and H(n=2) atom distributions occur in different spatial regions of the plume; direct analysis of the Stark broadening of the Balmer-β line would thus lead to an underestimate of the peak electron density. The present study highlights the necessity of careful intercomparisons between quantitative experimental data and model predictions in the development of a numerical treatment of the arc jet plasma. The kinetic scheme used here succeeds in describing many disparate observations--e.g., electron and H(n=2) number densities, spatial distributions of optical emission from the plume, the variation of these quantities with added flow of H2 and, when CH4 is added

  11. Dependence of spectral shape of bremsstrahlung spectra on atomic number of target materials in the photon energy range of 5-30 keV

    Dependence of spectral shape of total bremsstrahlung spectra i.e. the sum of ordinary bremsstrahlung (OB) and polarization bremsstrahlung (PB), on the atomic number (Z) of target materials (Al, Ti, Sn and Pb), produced by continuous beta particles of 90Sr and 204Tl, has been investigated in the photon energy region of 5-30 keV. It has been found that the spectral shape of total bremsstrahlung spectra, in terms of S (k, Z) i.e. the number of photons of energy k per moc2 per beta disintegration, is not linearly dependent on the atomic number (Z) of the target material and rather it is proportional to Zn. At lower photon energies, the index values ‘n’ of Z-dependence are much higher than unity, which is due to the larger contribution of PB into OB. The decrease in ‘n’ values with increase of photon energy is due to the decrease in contribution of PB into OB. It is clear that the index ‘n’ values obtained from the modified Elwert factor (relativistic) Bethe-Heitler theory, which include the contribution PB into OB, are in agreement with the experimentally measured results using X-PIPS Si(Li) detector. Hence the contribution of PB into the formation of a spectral shape of total bremsstrahlung spectra plays a vital role.

  12. Experimental measurement of effective atomic number of composite materials for Compton effect in the -ray region 280–1115 keV by a new method

    S Prasanna Kumar; T K Umesh

    2011-08-01

    In this paper, we report a new method to determine the effective atomic number, 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 eff for different inorganic compounds containing elements in the range = 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 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.

  13. A comparative study on total reflection X-ray fluorescence determination of low atomic number elements in air, helium and vacuum atmospheres using different excitation sources

    A comparison of trace element determinations of low atomic number (Z) elements Na, Mg, Al, P, K and Ca in air, helium and vacuum atmospheres using W Lβ1, Mo Kα and Cr Kα excitations has been made. For Mo Kα and W Lβ1 excitations a Si (Li) detector with beryllium window was used and measurements were performed in air and helium atmospheres. For Cr Kα excitation, a Si (Li) detector with an ultra thin polymer window (UTW) was used and measurements were made in vacuum and air atmospheres. The sensitivities of the elemental X-ray lines were determined using TXRF spectra of standard solutions and processing them by IAEA QXAS program. The elemental concentrations of the elements in other solutions were determined using their TXRF spectra and pre-determined sensitivity values. The study suggests that, using the above experimental set up, Mo Kα excitation is not suited for trace determination of low atomic number element. Excitation by WLβ1 and helium atmosphere, the spectrometer can be used for the determination of elements with Z = 15 (P) and above with fairly good detection limits whereas Cr Kα excitation with ultra thin polymer window and vacuum atmosphere is good for the elements having Z = 11 (Na) and above. The detection limits using this set up vary from 7048 pg for Na to 83 pg for Ti. - Highlights: • TXRF conditions are optimized for low atomic number (Z) element determinations. • Mo Kα with Be window detector can be used for elements with Z ≥ 20 (K). • W Lβ1 with Be window detector can be used for elements with Z ≥ 15 (P). • Cr Kα, UTW detector and vacuum atmosphere are suitable for elements with Z ≥ 11 (Na). • For the elements with Z ≥ 11 (Na), a separate study is needed

  14. Quantification of differences in the effective atomic numbers of healthy and cancerous tissues: A discussion in the context of diagnostics and dosimetry

    Taylor, M. L. [School of Applied Sciences and Health Innovation Research Institute, RMIT University, Melbourne 3000 (Australia); Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne 3001 (Australia) and Medical Physics, WBRC, Alfred Hospital, Melbourne 3000 (Australia)

    2012-09-15

    Purpose: There are a range of genetic and nongenetic factors influencing the elemental composition of different human tissues. The elemental composition of cancerous tissues frequently differs from healthy tissue of the same organ, particularly in high-Z trace element concentrations. For this reason, one could suggest that this may be exploited in diagnostics and perhaps even influence dosimetry. Methods: In this work, for the first time, effective atomic numbers are computed for common cancerous and healthy tissues using a robust, energy-dependent approach between 10 keV and 100 MeV. These are then quantitatively compared within the context of diagnostics and dosimetry. Results: Differences between effective atomic numbers of healthy and diseased tissues are found to be typically less than 10%. Fibrotic tissues and calcifications of the breast exhibit substantial (tens to hundreds of percent) differences to healthy tissue. Expectedly, differences are most pronounced in the photoelectric regime and consequently most relevant for kV imaging/therapy and radionuclides with prominent low-energy peaks. Cancerous tissue of the testes and stomach have lower effective atomic numbers than corresponding healthy tissues, while diseased tissues of the other organ sites typically have higher values. Conclusions: As dose calculation approaches improve in accuracy, there may be an argument for the explicit inclusion of pathologies. This is more the case for breast, penile, prostate, nasopharyngeal, and stomach cancer, less so for testicular and kidney cancer. The calculated data suggest dual-energy computed tomography could potentially improve lesion identification in the aforementioned organs (with the exception of testicular cancer), with most import in breast imaging. Ultimately, however, the differences are very small. It is likely that the assumption of a generic 'tissue ramp' in planning will be sufficient for the foreseeable future, and that the Z differences do

  15. Total gamma ray cross sections and effective atomic numbers in compounds in the energy region 32 to 662 keV

    Total photon mass attenuation cross sections in seven compounds were measured at eight photon energies from 32 to 662 keV on a good geometry set up using two NaI(Tl) scintillation counters in conjunction with a single channel analyser for the detection of low and medium energy photons. The theoretical values of the cross sections for the compounds are compared making use of the sum-rule. Using these cross sections the total effective atomic numbers in compounds are obtained. (author)

  16. Determining the mass attenuation coefficient, effective atomic number, and electron density of raw wood and binderless particleboards of Rhizophora spp. by using Monte Carlo simulation

    Mohammad W. Marashdeh; Ibrahim F. Al-Hamarneh; Eid M. Abdel Munem; A.A. Tajuddin; Alawiah Ariffin; Saleh Al-Omari

    2015-01-01

    Rhizophora spp. wood has the potential to serve as a solid water or tissue equivalent phantom for photon and electron beam dosimetry. In this study, the effective atomic number (Zeff) and effective electron density (Neff) of raw wood and binderless Rhizophora spp. particleboards in four different particle sizes were determined in the 10–60 keV energy region. The mass attenuation coefficients used in the calculations were obtained using the Monte Carlo N-Particle (MCNP5) simulation code. The M...

  17. Cold Incineration of Chlorophenols in Aqueous Solution by Advanced Electrochemical Process Electro-Fenton. Effect of Number and Position of Chlorine Atoms on the Degradation Kinetics

    Oturan, Nihal; Panizza, Marco; Oturan, Mehmet A.

    2009-09-01

    This study reports the kinetics of the degradation of several chlorophenols (CPs), such as monochlorophenols (2-chlorophenol and 4-chlorophenol), dichlorophenols (2,4-dichlorophenol and 2,6- dichlorophenol), trichlorophenols (2,3,5- trichlorophenol and 2,4,5-trichlorophenol), 2,3,5,6-tetrachlorophenol, and pentachlorophenol, by the electro-Fenton process using a carbon felt cathode and a Pt anode. The effect of number and the position of the chlorine atoms in the aromatic ring on the oxidative degradation rate was evaluated and discussed. The oxidation reaction of all the CPs with hydroxyl radicals evidenced a pseudo-first-order kinetics and the rate constant decreased with increasing the number of chlorine atoms. The absolute rate constant of second-order reaction kinetics between CPs and •OH was determined by the competition kinetics method in the range of (3.56-7.75) × 109 M-1 s-1 and follows the same sequence of the apparent rate constants. The mineralization of several CPs and of a mixture of all CPs under study was monitored by the total organic carbon (TOC) removal and the chlorine release during mineralization was followed by ion chromatography. Our results demonstrated that more chlorinated phenols are more difficult to mineralize; however for all the tested CPs, almost quantitative release of chloride ions was obtained after 6 h of treatment.

  18. Effective atomic numbers of different types of materials for proton interaction in the energy region 1 keV–10 GeV

    Kurudirek, Murat, E-mail: mkurudirek@gmail.com

    2014-10-01

    The effective atomic numbers (Z{sub eff}) of different types of materials such as tissues, tissue equivalents, organic compounds, glasses and dosimetric materials have been calculated for total proton interactions in the energy region 1 keV–10 GeV. Also, effective atomic numbers relative to water (Z{sub eff}RW) have been presented in the entire energy region for the materials that show better water equivalent properties. Some human tissues such as adipose tissue, bone compact, muscle skeletal and muscle striated have been investigated in terms of tissue equivalency by comparing Z{sub eff} values and the better tissue equivalents have been determined for these tissues. With respect to the variation of Z{sub eff} with kinetic energy, it has been observed that Z{sub eff} seems to be more or less the same in the energy region 400 keV–10 GeV for the given materials except for the photographic emulsion, calcium fluoride, silicon dioxide, aluminum oxide and Teflon. The values of Z{sub eff} have found to be constant for photographic emulsion after 1 GeV, for calcium fluoride between 1 MeV and 1 GeV and for silicon dioxide, aluminum oxide and Teflon between 400 keV and 1 GeV. This constancy clearly shows the availability of using Z{sub eff} in estimating radiation response of the materials at first glance.

  19. Survey of existing literature in the field of shock-absorbing materials with a view to subsequent adaptation of plastic deformation codes. Phase 1

    Shock-absorbing materials and structures can be used as part of the transport container structure or of the truck equipment. An extensive survey of the literature has provided much information. Investigation has been made to define the required experimental procedures necessary to measure the misssing material properties. Three codes had been selected: EURDYN, MARC-CDC and SAMCEF. For code evaluation, a schematic container model has been considered to serve as a benchmark for the evaluation of plastic deformation. For the shock-calculation, the container falls from a height of 9 meters along the direction of its cylinder axis on an unyielded flat surface. The EURDYN computer code, has been selected first as it is especially designed to handle dynamic problems, preferably plastic ones. Indeed, EURDYN uses an explicit integration scheme versus time, which makes it quite efficient to run short deformation processes such as absorber collapses. The SAMCEF computer code could not readily calculate the benchmark, also a visco-plastic flow model has been added to it. The MARC computer code was supposed to be a candidate to run shock-calculation but extensive computing time and engineering efforts would be required, it was replaced by the PLEXUS code. The results obtained using the SAMCEF programme confirm those obtained with EURDYN. The PLEXUS results are in between. The proposed benchmark calculation is at the border of the capabilities of the most advanced computer codes for plastic-dynamic calculations. Indeed, a complex energy absorption process seems to take place in a narrow region, moving versus time, where very large shape inversions occur. That requires an accurate modelling of the system in the deformed regions and a skilful choice of the numerical parameters of the computer run. The three tested codes gave qualitatively consistent results and confirm some scarce experimental results

  20. Measurement of electron density and effective atomic number by dual-energy scan using a 320-detector computed tomography scanner with raw data-based analysis: a phantom study.

    Tatsugami, Fuminari; Higaki, Toru; Kiguchi, Masao; Tsushima, So; Taniguchi, Akira; Kaichi, Yoko; Yamagami, Takuji; Awai, Kazuo

    2014-01-01

    We evaluated the accuracy of the electron densities and effective atomic numbers determined by raw data-based dual-energy analysis on a 320-detector computed tomography scanner. The mean (SD) errors between the measured and true electron densities and between the measured and true effective atomic numbers were 1.3% (1.5%) and 3.1% (3.2%), respectively. Electron densities and effective atomic numbers can be determined with high accuracy, which may help to improve accuracy in radiotherapy treatment planning. PMID:24983439

  1. Effective atomic number and electron density of amino acids within the energy range of 0.122-1.330 MeV

    More, Chaitali V.; Lokhande, Rajkumar M.; Pawar, Pravina P.

    2016-08-01

    Photon attenuation coefficient calculation methods have been widely used to accurately study the properties of amino acids such as n-acetyl-L-tryptophan, n-acetyl-L-tyrosine, D-tryptophan, n-acetyl-L-glutamic acid, D-phenylalanine, and D-threonine. In this study, mass attenuation coefficients (μm) of these amino acids for 0.122-, 0.356-, 0.511-, 0.662-, 0.884-, 1.170, 1.275-, 1.330-MeV photons are determined using the radio-nuclides Co57, Ba133, Cs137, Na22, Mn54, and Co60. NaI (Tl) scintillation detection system was used to detect gamma rays with a resolution of 8.2% at 0.662 MeV. The calculated attenuation coefficient values were then used to determine total atomic cross sections (σt), molar extinction coefficients (ε), electronic cross sections (σe), effective atomic numbers (Zeff), and effective electron densities (Neff) of the amino acids. Theoretical values were calculated based on the XCOM data. Theoretical and experimental values are found to be in a good agreement (errorenergy are shown graphically. The values of μm, σt, ε, σe are higher at lower energies, and they decrease sharply as energy increases; by contrast, Zeff and Neff were found to be almost constant.

  2. Post-irradiation-examination results for absorber material irradiation rig AMIR-6. The results of non-destructive examination for capsules

    Irradiation tests of Absorber Material Irradiation Rig (AMIR) have been continuously conducted, using the experimental fast reactor Joyo. AMIR-6, which was submitted for post-irradiation-examinations (PIE) this time, was irradiated in order to evaluate the limit of failure in control rods and confirm the effect of method for suppression of relocation caused by cracking of boron carbide (B4C) pellets. According to this purpose, gap size between B4C pellet and cladding tube (inner capsule tube), enrichment of 10B, thickness of cladding tube and its material were changed in this test. In addition, thin shroud tube wrapping B4C pellets was used as the method for suppression of relocation. Capsules were loaded in compartments, which had the upper and lower stairs, and irradiation rig AMIR-6 was constructed of seven compartments in total. The irradiation capsule had double tubes, namely inner capsule tube and outer capsule tube. Between these tubes, sodium was filled. AMIR-6 was irradiated at the 6 raw in Joyo Mark-II core up to 106 x 1026 cap/m3 (max. burn-up) and 3.82 x 1026 n/m2 (max, fluence). Irradiation temperatures were evaluated from 530 to 890 degC in design. Extraordinary results were observed for lower capsules by weight measurement performed. So, detailed visual inspection was carried out for these capsules. Consequently, sodium entered from the crack of screwhead attached to the outer tube in three irradiation capsules, whose weight increased. It was recognized that the sodium level between cladding tube and outer tube was lower in six capsules of lower stairs. Cladding crack was found out in three cladding tubes of lower irradiation capsule. It was suggested that the crack become for decrease of strength of cladding tube because those temperature increased at the position where sodium was not filled. The irradiation capsule using a shroud tube showed no diameter increase and ovality in the cladding. It is guessed from the results that the function as the

  3. Thermal conversion of an Fe3O4@metal-organic framework: a new method for an efficient Fe-Co/nanoporous carbon microwave absorbing material

    Zhang, Xingmiao; Ji, Guangbin; Liu, Wei; Quan, Bin; Liang, Xiaohui; Shang, Chaomei; Cheng, Yan; Du, Youwei

    2015-07-01

    A novel FeCo nanoparticle embedded nanoporous carbon composite (Fe-Co/NPC) was synthesized via in situ carbonization of dehydro-ascorbic acid (DHAA) coated Fe3O4 nanoparticles encapsulated in a metal-organic framework (zeolitic imidazolate framework-67, ZIF-67). The molar ratio of Fe/Co significantly depends on the encapsulated content of Fe3O4 in ZIF-67. The composites filled with 50 wt% of the Fe-Co/NPC-2.0 samples in paraffin show a maximum reflection loss (RL) of -21.7 dB at a thickness of 1.2 mm; in addition, a broad absorption bandwidth for RL embedded nanoporous carbon composite (Fe-Co/NPC) was synthesized via in situ carbonization of dehydro-ascorbic acid (DHAA) coated Fe3O4 nanoparticles encapsulated in a metal-organic framework (zeolitic imidazolate framework-67, ZIF-67). The molar ratio of Fe/Co significantly depends on the encapsulated content of Fe3O4 in ZIF-67. The composites filled with 50 wt% of the Fe-Co/NPC-2.0 samples in paraffin show a maximum reflection loss (RL) of -21.7 dB at a thickness of 1.2 mm; in addition, a broad absorption bandwidth for RL < -10 dB which covers from 12.2 to 18 GHz can be obtained, and its minimum reflection loss and bandwidth (RL values exceeding -10 dB) are far greater than those of commercial carbonyl iron powder under a very low thickness (1-1.5 mm). This study not only provides a good reference for future preparation of carbon-based lightweight microwave absorbing materials but also broadens the application of such kinds of metal-organic frameworks. Electronic supplementary information (ESI) available: Additional TEM image, SEM images, elemental mapping, Raman spectrum, dielectric loss tangent, magnetic loss tangent, and values of μ''(μ')-2f-1. See DOI: 10.1039/c5nr03176a

  4. Effective atomic numbers and electron densities of bacteriorhodopsin and its comprising amino acids in the energy range 1 keV–100 GeV

    Ahmadi, Morteza; Lunscher, Nolan [Waterloo Institute for Nanotechnology and Department of Systems Design Engineering, University of Waterloo, 200 University Ave., W., Waterloo, Ontario, Canada N2L 3G1 (Canada); Yeow, John T.W., E-mail: jyeow@uwaterloo.ca [Waterloo Institute for Nanotechnology and Department of Systems Design Engineering, University of Waterloo, 200 University Ave., W., Waterloo, Ontario, Canada N2L 3G1 (Canada)

    2013-04-01

    Recently, there has been an interest in fabrication of X-ray sensors based on bacteriorhodopsin, a proton pump protein in cell membrane of Halobacterium salinarium. Therefore, a better understanding of interaction of X-ray photons with bacteriorhodopsin is required. We use WinXCom program to calculate the mass attenuation coefficient of bacteriorhodopsin and its comprising amino acids for photon energies from 1 keV to 100 GeV. These amino acids include alanine, arginine, asparagine, aspartic acid, glutamine, glutamic acid, glycine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, Asx1, Asx2, Glx1 and Glx2. We then use that data to calculate effective atomic number and electron densities for the same range of energy. We also emphasize on two ranges of energies (10–200 keV and 1–20 MeV) in which X-ray imaging and radiotherapy machines work.

  5. Determination of the effective atomic numbers and electron densities for YBaCuO superconductor in the range 59.5-136 keV

    The effective atomic numbers and electron densities of YBa2Cu3O7-δ superconductor at 59.5, 65.2, 77.1, 94.6, 122 and 136 keV were calculated by using the measured mass attenuation coefficients. Measurements were made by performing transmission experiments in a well-collimated narrow beam geometry set-up by employing Si(Li) detector with a resolution of 0.16 keV at 5.9 keV. These values are found to be in good agreement with theoretical values calculated based on XCOM data. The observed crystal structure of YBa2Cu3O7-δ superconductor is close to the theoretical structure. Zeff and Nel experimental values showed good agreement with the theoretical values for calcined and sintered YBa2Cu3O7-δ

  6. Determination of the effective atomic numbers and electron densities for YBaCuO superconductor in the range 59.5 136 keV

    Baltaş, H.; Çevik, U.

    2008-04-01

    The effective atomic numbers and electron densities of YBa 2Cu 3O 7-δ superconductor at 59.5, 65.2, 77.1, 94.6, 122 and 136 keV were calculated by using the measured mass attenuation coefficients. Measurements were made by performing transmission experiments in a well-collimated narrow beam geometry set-up by employing Si(Li) detector with a resolution of 0.16 keV at 5.9 keV. These values are found to be in good agreement with theoretical values calculated based on XCOM data. The observed crystal structure of YBa 2Cu 3O 7-δ superconductor is close to the theoretical structure. Zeff and Nel experimental values showed good agreement with the theoretical values for calcined and sintered YBa 2Cu 3O 7-δ.

  7. Studies on effective atomic numbers for photon energy absorption and electron density of some narcotic drugs in the energy range 1 keV-20 MeV

    Gounhalli, Shivraj G.; Shantappa, Anil; Hanagodimath, S. M.

    2013-04-01

    Effective atomic numbers for photon energy absorption ZPEA,eff, photon interaction ZPI,eff and for electron density Nel, have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for narcotic drugs, such as Heroin (H), Cocaine (CO), Caffeine (CA), Tetrahydrocannabinol (THC), Cannabinol (CBD), Tetrahydrocannabivarin (THCV). The ZPEA,eff, ZPI,eff and Nel values have been found to change with energy and composition of the narcotic drugs. The energy dependence ZPEA,eff, ZPI,eff and Nel is shown graphically. The maximum difference between the values of ZPEA,eff, and ZPI,eff occurs at 30 keV and the significant difference of 2 to 33% for the energy region 5-100 keV for all drugs. The reason for these differences is discussed.

  8. Investigation of the on-axis atom number density in the supersonic gas jet under high gas backing pressure by simulation

    Guanglong Chen

    2015-10-01

    Full Text Available The supersonic gas jets from conical nozzles are simulated using 2D model. The on-axis atom number density in gas jet is investigated in detail by comparing the simulated densities with the idealized densities of straight streamline model in scaling laws. It is found that the density is generally lower than the idealized one and the deviation between them is mainly dependent on the opening angle of conical nozzle, the nozzle length and the gas backing pressure. The density deviation is then used to discuss the deviation of the equivalent diameter of a conical nozzle from the idealized deq in scaling laws. The investigation on the lateral expansion of gas jet indicates the lateral expansion could be responsible for the behavior of the density deviation. These results could be useful for the estimation of cluster size and the understanding of experimental results in laser-cluster interaction experiments.

  9. Mass attenuation coefficient (μ/ρ), effective atomic number (Zeff) and measurement of x-ray energy spectra using based calcium phosphate biomaterials: a comparative study

    In dentistry, alveolar bone regeneration procedures using based calcium phosphate biomaterials have been shown effective. However,there are not reports in the literature of studies the interaction of low energy radiation in these biomaterials used as attenuator and not being then allowed a comparison between the theoretical values and experimental.The objective of this study was to determine the interaction of radiation parameters of four dental biomaterials - BioOss, Cerasorb M Dental, Straumann Boneceramic and Osteogen for diagnostic radiology qualities. As a material and methods, the composition of the biomaterials was determined by the analytical techniques. The samples with 0.181 cm to 0,297 cm thickness were experimentally used as attenuators for the measurement of the transmitted X-rays spectra in X-ray equipment with 50 to 90 kV range by spectrometric system comprising the Cd Te detector. After this procedure, the mass attenuation coefficient, the effective atomic number were determined and compared between all the specimens analyzed, using the program WinXCOM in the range of 10 to 200 keV. In all strains examined observed that the energy spectrum of x-rays transmitted through the BioOss has the mean energy slightly smaller than the others biomaterials for close thickness. The μ/ρ and Zeff of the biomaterials showed its dependence on photon energy and atomic number of the elements of the material analyzed. It is concluded according to the methodology employed in this study that the measurements of x-ray spectrum, μ/ρ and Zeff using biomaterials as attenuators confirmed that the thickness, density, composition of the samples, the incident photon energy are factors that determine the characteristics of radiation in a tissue or equivalent material. (Author)

  10. The effect of phenomenological modeling of z-pinch implosions on the scaling of k-shell emission with atomic number and mass

    Recent 1-D phenomenological modeling of plasma turbulence by enhancing transport coefficients has shown that it is possible to achieve good agreement with experimental plasma conditions at stagnation, especially when compared to previous laminar flow calculations. Since this original phenomenological study focused upon only a single Physics International Inc. argon experiment, it is important to build a stronger foundation for this modeling. This is accomplished by: (1) including turbulence effects phenomenologically in the 1-D, radiation, MHD average fluid description of the turbulent flow by enhancing the resistivity Ω, viscosity υ, and heat conductivity κ transport coefficients; (2) finding a set of (κ,υ,Ω) coefficients that reasonably produces the stagnation temperatures and densities of a Physics International Inc. aluminum experiment; (3) this choice of transport coefficients is then tested for dependence on mass loading m and atomic number Z by comparing calculated implosion conditions with those found in a variety of PI aluminum and argon experiments. The authors find that the choice of enhanced transport coefficients that produces good agreement with the stagnation temperatures and densities of the single PI aluminum experiment also gives acceptable agreement for the other aluminum and argon experiments. Based on the presumption that a better representation of plasma conditions at stagnation also gives rise to more realistic K-shell yield scaling with atomic number, the minimum load mass and kinetic energy (machine energy) requirements needed to efficiently produce K-shell emission are calculated for aluminum and argon using enhanced transport calculations. These results are then extrapolated to other Z materials and compared with predictions of the original laminar flow scaling study. Implications of this work for large current machines will be presented

  11. Effective atomic numbers and electron densities of some human tissues and dosimetric materials for mean energies of various radiation sources relevant to radiotherapy and medical applications

    Effective atomic numbers, Zeff, and electron densities, neff, are convenient parameters used to characterise the radiation response of a multi-element material in many technical and medical applications. Accurate values of these physical parameters provide essential data in medical physics. In the present study, the effective atomic numbers and electron densities have been calculated for some human tissues and dosimetric materials such as Adipose Tissue (ICRU-44), Bone Cortical (ICRU-44), Brain Grey/White Matter (ICRU-44), Breast Tissue (ICRU-44), Lung Tissue (ICRU-44), Soft Tissue (ICRU-44), LiF TLD-100H, TLD-100, Water, Borosilicate Glass, PAG (Gel Dosimeter), Fricke (Gel Dosimeter) and OSL (Aluminium Oxide) using mean photon energies, Em, of various radiation sources. The used radiation sources are Pd-103, Tc-99, Ra-226, I-131, Ir-192, Co-60, 30 kVp, 40 kVp, 50 kVp (Intrabeam, Carl Zeiss Meditec) and 6 MV (Mohan-6 MV) sources. The Em values were then used to calculate Zeff and neff of the tissues and dosimetric materials for various radiation sources. Different calculation methods for Zeff such as the direct method, the interpolation method and Auto-Zeff computer program were used and agreements and disagreements between the used methods have been presented and discussed. It has been observed that at higher Em values agreement is quite satisfactory (Dif.<5%) between the adopted methods. - Highlights: • Mean energies for different radiation sources have been determined. • Human tissues and dosimetric materials have been investigated according to different sources. • Different methods were applied for calculation of Eeff, Zeff and neff

  12. Atomic polarizabilities

    Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  13. Atomic polarizabilities

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed

  14. Extrapolation of the Bethe equation for electron stopping powers to intermediate and low electron energies by empirical simulation of target effective mean excitation energy and atomic number

    A series of simple stopping power (SP) formulas, modified from the relativistic Bethe equation, is presented that is based on the concepts of target effective atomic number and mean excitation energy (MEE). The analytical model function is constructed to approximate experimental or calculated SPs at low electron energies and tend asymptotically to the relativistic Bethe function at high energies. The energy dependencies of our effective values, in contrast with theoretical approaches, are defined empirically by parametrization with tuning parameters. A least-squares fitting routine based on the Levenberg–Marquardt algorithm was developed. We utilize the material parameters and numerical calculations of SPs from optical data using the full Penn-algorithm. Our formula is thought to be applicable for energies above 60 eV. Our simulations of SPs for 41 elemental solids are found to be in good agreement with published numerical results. The flexibility of a general empirical formula is shown. Shortened formulas were developed that are applicable for particular energy ranges, and effective MEEs are proposed that differ from previously recommended values. The presented formulas may be used for analytical calculation of SPs over a broad projectile energy region

  15. Portable and autonomous X-ray equipment for in-situ threat materials identification by effective atomic number high-accuracy measurement

    Iovea, M.; Neagu, M.; Mateiasi, G.; Duliu, O.

    2011-06-01

    A novel portable and autonomous X-ray dual-energy Radioscopy equipment, developed for bomb squad interventions and NDT applications and capable of in-situ digital radiography imaging with measurement of the effective Atomic number of materials (Zeff), is presented. The system consists of a 2D dual-energy X-ray detector based on a rapidly translated linear array, a portable X-ray source and dedicated software running on a laptop or tablet PC. By measurement of the collected x-ray intensities at two different energy spectra, the system can directly compute the material Zeff value for various organic materials contained in the scanned object and then identify them from a database list. The entire system calibration has been obtained using explosive simulants with known Zeff values, the measurement error of Zeffbeing around +/-3.5 % with respect to the reference values. The excellent image resolution and the ability of the automated threat identification algorithm are presented for experiments with a briefcase and a hand-held baggage having various domestic objects and an explosive simulant inside.

  16. Extracting material parameters from x-ray attenuation: a CT feasibility study using kilovoltage synchrotron x-rays incident upon low atomic number absorbers

    The work reported here is a feasibility study of the extraction of material parameters from measurements of the linear x-ray attenuation coefficient of low atomic number absorbers. Computed tomography (CT) scans of small samples containing several liquids and solids were carried out with synchrotron radiation at the Australian National Beamline Facility (BL 20B) in Japan. Average values of the x-ray linear attenuation coefficient were extracted for each material for x-ray energies ranging from 11 keV to 20.5 keV. The electron density was estimated by applying results derived from a parametrization of the x-ray linear attenuation coefficient first developed by Jackson and Hawkes and extended for this work. Average estimates for the electron density of triethanolamine and acetic acid were made to within +5.3% of the actual value. Other materials examined included furfuraldehyde, perspex and teflon, for which average estimates of the electron density were less than 10% in excess of the calculated value

  17. 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.

    Kurudirek, Murat; Aygun, Murat; Erzeneoğlu, Salih Zeki

    2010-06-01

    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. PMID:20080413

  18. Estimation of effective atomic numbers of some solutions for photon energy absorption in the energy region 0.2-1.5 MeV: An alternative method

    Kurudirek, Murat

    2011-12-01

    The effective atomic numbers (ZPEAeff), which are used to describe the composite materials in terms of equivalent elements, have been estimated in some solutions for photon energy absorption in the energy region 0.2-1.5 MeV. Since the mass energy absorption (μen/ρ) and mass attenuation coefficients (μ/ρ) remain more or less the same for any given material in the photon energy region 0.2-1.5 MeV where Compton scattering is the main dominant photon interaction process, semi-empirical relations including both μen/ρ and μ/ρ have been constituted as a function of energy. These parameters were then used to obtain ZPEAeff with the help of a Z-wise interpolation procedure. The results were compared with the experimental as well as other theoretical estimations wherever possible. Consequently, the present method is found to be readily applicable to the given solutions in order to estimate accurate values of ZPEAeff for which it is not possible to directly obtain experimentally using the conventional gamma spectrometry system.

  19. Estimation of effective atomic numbers of some solutions for photon energy absorption in the energy region 0.2-1.5 MeV: An alternative method

    The effective atomic numbers (ZPEAeff), which are used to describe the composite materials in terms of equivalent elements, have been estimated in some solutions for photon energy absorption in the energy region 0.2-1.5 MeV. Since the mass energy absorption (μen/ρ) and mass attenuation coefficients (μ/ρ) remain more or less the same for any given material in the photon energy region 0.2-1.5 MeV where Compton scattering is the main dominant photon interaction process, semi-empirical relations including both μen/ρ and μ/ρ have been constituted as a function of energy. These parameters were then used to obtain ZPEAeff with the help of a Z-wise interpolation procedure. The results were compared with the experimental as well as other theoretical estimations wherever possible. Consequently, the present method is found to be readily applicable to the given solutions in order to estimate accurate values of ZPEAeff for which it is not possible to directly obtain experimentally using the conventional gamma spectrometry system.

  20. Evaluation of resolved resonance parameters of fission product nuclides with atomic numbers Z=46-51 for JENDL-3.2

    Nakajima, Yutaka [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1996-08-01

    Resolved resonance parameters of the following fission product nuclides with atomic numbers Z=46-51 have been evaluated for JENDL-3.2: {sup 102,104,105,106,107,108,110}Pd, {sup 107,109,110m}Ag, {sup 106,108,110,111,112,113,114,116}Cd, {sup 113,115I}n, {sup 121,123}Sb. Evaluation was made on the basis of JENDL-2 for most nuclides and of the data recommended by Mughabghab et al. for the nuclides whose data have not been contained in JENDL-2. Data measured after the JENDL-2 evaluation (1982) have been taken into account in the evaluation. Spin of the resonance state and angular momentum of the incident neutron have been given for all levels. When there exist no measured data, the spin has been given tentatively on the basis of a random sampling technique using their statistical properties, and the angular momentum was also tentatively given on the basis of the Bayes`s theorem on conditional probability using the s- and p-wave strength functions and average level spacings. The resonance parameters have been evaluated so as to reproduce measured capture area of individual resonance levels, thermal cross section and resonance integral. Evaluated results have been compiled into JENDL-3.2 in the formats of ENDF-5 and ENDF-6. (author)

  1. Determining the mass attenuation coefficient, effective atomic number, and electron density of raw wood and binderless particleboards of Rhizophora spp. by using Monte Carlo simulation

    Mohammad W. Marashdeh

    2015-01-01

    Full Text Available Rhizophora spp. wood has the potential to serve as a solid water or tissue equivalent phantom for photon and electron beam dosimetry. In this study, the effective atomic number (Zeff and effective electron density (Neff of raw wood and binderless Rhizophora spp. particleboards in four different particle sizes were determined in the 10–60 keV energy region. The mass attenuation coefficients used in the calculations were obtained using the Monte Carlo N-Particle (MCNP5 simulation code. The MCNP5 calculations of the attenuation parameters for the Rhizophora spp. samples were plotted graphically against photon energy and discussed in terms of their relative differences compared with those of water and breast tissue. Moreover, the validity of the MCNP5 code was examined by comparing the calculated attenuation parameters with the theoretical values obtained by the XCOM program based on the mixture rule. The results indicated that the MCNP5 process can be followed to determine the attenuation of gamma rays with several photon energies in other materials.

  2. Determining the mass attenuation coefficient, effective atomic number, and electron density of raw wood and binderless particleboards of Rhizophora spp. by using Monte Carlo simulation

    Marashdeh, Mohammad W.; Al-Hamarneh, Ibrahim F.; Abdel Munem, Eid M.; Tajuddin, A. A.; Ariffin, Alawiah; Al-Omari, Saleh

    Rhizophora spp. wood has the potential to serve as a solid water or tissue equivalent phantom for photon and electron beam dosimetry. In this study, the effective atomic number (Zeff) and effective electron density (Neff) of raw wood and binderless Rhizophora spp. particleboards in four different particle sizes were determined in the 10-60 keV energy region. The mass attenuation coefficients used in the calculations were obtained using the Monte Carlo N-Particle (MCNP5) simulation code. The MCNP5 calculations of the attenuation parameters for the Rhizophora spp. samples were plotted graphically against photon energy and discussed in terms of their relative differences compared with those of water and breast tissue. Moreover, the validity of the MCNP5 code was examined by comparing the calculated attenuation parameters with the theoretical values obtained by the XCOM program based on the mixture rule. The results indicated that the MCNP5 process can be followed to determine the attenuation of gamma rays with several photon energies in other materials.

  3. Charge fraction of 6.0 MeV/n heavy ions with a carbon foil: Dependence on the foil thickness and projectile atomic number

    Sato, Y; Muramatsu, M; Murakami, T; Yamada, S; Kobayashi, C; Kageyama, Y; Miyoshi, T; Ogawa, H; Nakabushi, H; Fujimoto, T; Miyata, T; Sano, Y

    2003-01-01

    We measured the charge fraction of 6.0 MeV/n heavy ions (C, Ne, Si, Ar, Fe and Cu) with a carbon foil at the NIRS-HIMAC injector. At this energy they are stripped with a carbon foil before being injected into two synchrotron rings with a maximum energy of 800 MeV/n. In order to find the foil thickness (D sub E) at which an equilibrium charge state distribution occurs, and to study the dependence of the D sub E -values on the projectile atomic number, we measured the exit charge fractions for foil thicknesses of between 10 and 350 mu g/cm sup 2. The results showed that the D sub E -values are 21.5, 62.0, 162, 346, 121, 143 mu g/cm sup 2 for C, Ne, Si, Ar, Fe, Cu, respectively. The fraction of Ar sup 1 sup 8 sup + ions was actually improved to 33% at 320 mu g/cm sup 2 from approx 15% at 100 mu g/cm sup 2. For Fe and Cu ions, the D sub E -values were found to be only 121 and 143 mu g/cm sup 2; there is a large gap between Ar and Fe, which is related to the differences in the ratio of the binding energy of the K-...

  4. 反应堆乏燃料贮运用中子吸收材料的研究进展%Research Progress in Neutron Absorbers Materials for Reactor Spent Fuel Storage and Transportation Applications

    李刚; 简敏; 王美玲; 王贯春; 刘晓珍

    2011-01-01

    从我国对乏燃料贮运用中子吸收材料的需求出发,简述了乏燃料贮运用中子吸收材料的特点、国内外研究及应用现状.重点阐述了含硼不锈钢、BC/Al、硼铝合金、含硼有机聚合物4种含硼中子吸收材料的制备工艺、性能以及存在的问题,同时对目前我国使用的不锈钢包覆金属镉中子吸收材料和国外正在研究的含钆合金中子吸收材料进行了概述.提出了BC/AI和硼钢两种中子吸收材料应作为进一步研究的重点.%Neutron absorber materials properties and their current research and application at home and abroad are presented from the demand for spent nuclear fuel transportation and storage application in China. There is a focus on four kinds of materials including borated steel, aluminum boron carbide metal matrix composites, boron aluminum alloys, boron-containing organic polymer. It is discussed these four materials preparation, performance cha-racteristics as well as the existing problems during the process of materials preparation and application. At the same time it is described that cadmium coated borated stainless steel neutron absorbing materials using in China nuclear power plants and gadolinium-containing neutron absorbing materials currently studying abroad. At last the direction pointed out of further study of borated steel and aluminum boron carbide metal matrix composites.

  5. On Application of Radar Absorbing Materials in Military Stealthy Packaging%雷达吸波材料在军品隐身防护包装中的应用探讨

    尹恩强; 刘兴海; 黎厚斌

    2011-01-01

    The importance of stealth protection in modern military packaging was analyzed. The mechanisms of radar absorbing materials (RAM) and main types of technology were introduced. The preparation of absorbing material coating and its progress in domestic and abroad were summarized. It was put forward that the stealthy packaging material for our military equipment should have good optical, radar, and IR stealth performance, multi-spectrum, intelligent as well as other good integrated stealth performance.%分析了当代军品包装中隐身防护的重要性,介绍了目前在隐身包装中占据主导地位的雷达吸波材料(RAM)的机理和主要技术种类,并对涂覆型吸波材料的制备方法和国内外的研究进展进行了综述,认为未来军品隐身包装防护材料应具有防雷达、光学、热红外侦察等多频谱且智能化综合隐身性能。

  6. A molecular dynamics study of the effect of thermal boundary conductance on thermal transport of ideal crystal of n-alkanes with different number of carbon atoms

    Rastgarkafshgarkolaei, Rouzbeh; Zeng, Yi; Khodadadi, J. M.

    2016-05-01

    Phase change materials such as n-alkanes that exhibit desirable characteristics such as high latent heat, chemical stability, and negligible supercooling are widely used in thermal energy storage applications. However, n-alkanes have the drawback of low thermal conductivity values. The low thermal conductivity of n-alkanes is linked to formation of randomly oriented nano-domains of molecules in their solid structure that is responsible for excessive phonon scattering at the grain boundaries. Thus, understanding the thermal boundary conductance at the grain boundaries can be crucial for improving the effectiveness of thermal storage systems. The concept of the ideal crystal is proposed in this paper, which describes a simplified model such that all the nano-domains of long-chain n-alkanes are artificially aligned perfectly in one direction. In order to study thermal transport of the ideal crystal of long-chain n-alkanes, four (4) systems (C20H42, C24H50, C26H54, and C30H62) are investigated by the molecular dynamics simulations. Thermal boundary conductance between the layers of ideal crystals is determined using both non-equilibrium molecular dynamics (NEMD) and equilibrium molecular dynamics (EMD) simulations. Both NEMD and EMD simulations exhibit no significant change in thermal conductance with the molecular length. However, the values obtained from the EMD simulations are less than the values from NEMD simulations with the ratio being nearly three (3) in most cases. This difference is due to the nature of EMD simulations where all the phonons are assumed to be in equilibrium at the interface. Thermal conductivity of the n-alkanes in three structures including liquid, solid, and ideal crystal is investigated utilizing NEMD simulations. Our results exhibit a very slight rise in thermal conductivity values as the number of carbon atoms of the chain increases. The key understanding is that thermal transport can be significantly altered by how the molecules and the

  7. Thin films of absorber material Cu2ZnSnS4 for solar cells

    Cazzaniga, Andrea Carlo; Ettlinger, Rebecca Bolt; Schou, Jørgen

    2014-01-01

    are deposited on Mo coated SLG in the temperature range from 25C to 500C. X-ray diffraction patterns show an increase in the intensity of main peak associated to kesterite CZTS up to asubstrate temperature of 300 C, then secondary phases start to show up and the main peak associated to kesterite drops down......Pulsed Laser Deposition technique is applied to the production of thin films of CZTS (Cu2ZnSnS4).This vacuum technique has proven to be particularly successful in the production of films with acomplex stoichiometry, as in the case of high temperature superconductors. The material ablated bythe...... laser pulse is transferred to the substrate at very high kinetic energy (~ keV), thus resulting inhigh mobility of the adsorpted atoms yet at low substrate temperatures. Since the reaction ofdecomposition of CZTS via S and SnS evaporation is the main problem all vacuum techniques haveto deal with...

  8. A Comparative Study of Co-electrodeposited Cu2ZnSnS4 Absorber Material on Fluorinated Tin Oxide and Molybdenum Substrates

    Sarswat, Prashant K.; Free, Michael L.

    2012-08-01

    A comparative study of electrochemically grown Cu2ZnSnS4 (CZTS) thin films on transparent conducting fluorinated tin oxide (FTO) electrodes and molybdenum-coated substrates was conducted. CZTS on FTO is highly desirable for bifacial-semitransparent photovoltaic applications for next-generation, environmentally friendly, high-efficiency solar panels. CZTS films were synthesized using single-stage electrochemical deposition followed by sulfur diffusion. Detailed comparisons of structural, morphological, electrochemical, and optical properties were performed using several techniques including Raman and ultraviolet-visible spectroscopy, atomic force microscopy, scanning electron microscopy, and photoelectrochemical characterization. All of the characterization experiments indicated that there is sufficient potential for electrochemically grown CZTS on FTO-coated glass as an alternative to CZTS on molybdenum-coated glass.

  9. Studies on mass attenuation coefficient, effective atomic number and electron density of some amino acids in the energy range 0.122–1.330 MeV

    The total mass attenuation coefficients of some amino acids, such as Glycine (C2H5NO2), DL-Alanine (C3H7NO2), Proline (C5H9NO2), L-Leucine (C6H13NO2 ), L-Arginine (C6H14N4O2) and L-Arginine Monohydrochloride (C6H15ClN4O2), were measured at 122, 356, 511, 662, 1170, 1275 and 1330 keV photon energies using a well-collimated narrow beam good geometry set-up. The gamma rays were detected using NaI (Tl) scintillation detection system with a resolution of 10.2% at 662 keV. The attenuation coefficient data were then used to obtain the effective atomic numbers (Zeff) and effective electron densities (Neff) of amino acids. It was observed that the effective atomic number (Zeff) and effective electron densities (Neff) tend to be almost constant as a function of gamma-ray energy. The results show that, the experimental values of mass attenuation coefficients, effective atomic numbers and effective electron densities are in good agreement with the theoretical values with less than 1% error. - Highlights: • Compute the Mass Attenuation Coefficient, effective atomic number and electron density of some amino acids. • Gamma ray attenuation studies on biologically important molecules have been carried out using narrow beam good geometry set up. • The values of Mass Attenuation Coefficient, effective atomic number and electron density of some amino acids are in agreement with the XCOM programme. • The measured mass attenuation coefficient for some amino acids are useful in medical field. • The data is useful in radiation dosimetry and other fields

  10. Development of New Absorber Materials to Achieve Organic Photovoltaic Commercial Modules with 15% Efficiency and 20 Years Lifetime: Cooperative Research and Development Final Report, CRADA Number CRD-12-498

    Olson, D.

    2014-08-01

    Under this CRADA the parties will develop intermediates or materials that can be employed as the active layer in dye sensitized solar cells printed polymer systems, or small molecule organic photovoltaics.