Tungsten (W) is a very heavy metal powder that is compatible with virtually all polymers at very high loadings by weight. It is dark gray in color and can produce a matte finish in high concentrations, providing substantial restrictions for color matching. Tungsten polymer (also known as tungsten poly) is a composition of various resins and tungsten powder which are mixed together through special metallurgical technology. Due to tungsten polymer has high density (13g/cc), excellent radiation attenuation properties, and environmental friendly, it is widely used to produced radiation shielding. Tungsten polymer radiation shielding can be abrasive on processing equipment, and it is a filler of choice in very thin walled devices where radiopacity.

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The lattice-vibration Raman spectrum of calcium tungstate has been measured, using excitation by a He-Ne laser. Eleven of the thirteen long-wave-length phonon modes which are Raman active in first order have been detected. Polarization studies have revealed the group-theoretical symmetries of ten of the phonons. The linewidths and relative intensities of the Raman peaks have also been measured. These results complement the information obtained from the infra-red reflection spectrum of calcium tungstate. The frequencies of the infrared and Raman active phonons are discussed in terms of the normal modes of the lattice.

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A technique which may be used to determine the light conversion efficiency (defined below) of thin fluorescent crystals is presented. The illuminance associated with the visible spectrum emitted by the material under a pulse of x rays and incident on a light intensifier tube is amplified by the tube and is eventually recorded by a photographic film placed on the other side of the tube. A calibration curve relating the conversion efficiency of the crystal (regarded as an unknown variable) and the resulting film density is first obtained analytically. This is then used, in conjunction with the experimentally measured film density, to yield the conversion efficiency. An application of this technique was made to the case of a calcium tungstate crystal, for which a conversion efficiency of [equiation] was determined.

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Interferometric measurements of the linear thermal expansion coefficients are reported for thec andacrystallographic axis directions of calcium tungstate in the temperature range 30–270°K. The results are believed to be accurate to within 2% at 270°K, falling to 25% at 30°K. The reduced mean Grüneisen parameter (χ _s γ _mean ) = βV/C _t, calculated from the volume expansion coefficient β and earlier heat-capacity measurements, falls with diminishing temperature. Detailed identification of contributions to the thermodynamic properties arising from translational, rotational, and internal modes of vibration is prevented by spectral overlap. The quasiharmonic approximation has been applied to calculate provisional reduced moments of a representative vibrational frequency spectrum, which are in qualitative accord with earlier findings based upon observations of infrared reflection and first-order Raman spectra.

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The temperature dependences from 4.2 to 300 K of the seven adiabatic elastic constants of CaWO₄ have been determined by measurements of ultrasound wave velocities using the `sing-around' and pulse superposition methods. The adiabatic elastic constants have been calculated from the measured ultrasound wave velocities by a perturbation method using just seven of the eleven measured velocities and by an iterative method using all the measured velocities; agreement has been found between the two sets of values. The complementary data on the thermal expansion and heat capacity at constant pressure of CaWO₄ have been used with the present results to find the isothermal elastic constants, the heat capacity at constant volume, the Grüneisen parameters, and the Debye characteristic temperature at 0 K. The Debye characteristic temperature has been found from the heat capacity at constant volume from 10 to 300 K after subtraction of the Einstein heat capacity terms from the total heat capacity.

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A calcium tungstate X-ray phosphor is disclosed which consists essentially of a calcium tungstate host and from about 50 to about 200 parts per million, based upon the weight of the host, of vanadium as a dopant. The disclosed phosphor exhibits no detectable lag or persistence and is appreciably brighter than prior X-ray phosphors. A process for producing the phosphor is also disclosed which process comprises forming an aqueous reaction media of a water-soluble calcium source and a water-soluble tungstate source having an excess of calcium, maintaining a temperature of above about 80°C for a time sufficient to form solid calcium tungstate having a stoichiometric excess of calcium, separating the solid calcium tungstate, adding from about 50 to 200 ppm of a vanadium source and a fluxing material, heating said calcium tungstate to a temperature of between about 700°C and 1150°C for a sufficient time to form a phosphor composition and washing the phosphor with sufficient water to remove any residual water soluble contaminants. An optional process is to add, in addition to the vanadium source, from about 0.05% to about 1.0%, based upon the weight of the host, of tungsten trioxide.

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The energy which must be absorbed in a CaWO₄ x-ray intensifying screen to produce unit net opetical density on a film has been evaluated by measurement and calculation for a screen-film system over a range of beam qualities (1.4--7.4 mm A1 HVL) spanning the diagnostic x-ray region. It was found to be constant within experimental error. The absorbed-energy constant for three additional CaWO₄ screens is presented for a single beam quality. To correct the estimation of absorbed energy, the fractional escape of tungsten K x rays has been evaluated and the results are presented as a function of phosphor loading. The absorbed-energy constant is useful for predicting optical density for variable beam conditions; a family of characteristic curves based on exposure is reduced to one curve for a particular film-screen system, expressed as optical density as a function of absorbed energy.

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CaWO₄ single crystals have been grown and compared by three different high temperature solution methods, viz. the normal flux-cooling procedure, the indirect flux-reaction technique and the isothermal flux-evaporation method. The typical as-grown bipyramidal crystals obtained by these methods have been found to be mostly large and perfect with varying degree of transparency. The crystals are characterised by using EDAX, X-ray diffraction, electrical conduction, micromechanical tests and chemical etching. The assessment of various characteristics of the grown crystals is likely to show enormous usefulness of the flux grown crystals.

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The silicon-molybdenum blue spectrophotometry was used to measure micro silicon in calcium tungstate and calcium titanale. The experiments were carried out to separate large quantities of interference elements of tungsten and titanium,and to analyse the factors influencing the silicon measurement. The measurement conditions were determined. The method is simple,convenient and accurate,and can be well repealed.

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The heart of an X-ray machine is an electrode pair -- a cathode and an anode -- that sits inside a glass vacuum tube. The cathode is a heated filament, like you might find in an older fluorescent lamp. The machine passes current through the filament, heating it up. The heat sputters electrons off of the filament surface. The positively-charged anode, a flat disc made of tungsten, draws the electrons across the tube.

The voltage difference between the cathode and anode is extremely high, so the electrons fly through the tube with a great deal of force. When a speeding electron collides with a tungsten atom, it knocks loose an electron in one of the atom's lower orbital. An electron in a higher orbital immediately falls to the lower energy level, releasing its extra energy in the form of a photon. It's a big drop, so the photon has a high energy level -- it is an X-ray photon.

Due to tungsten alloy has high density, excellent radiation attenuation properties, and environmental friendly, it is also can be used to produce into tungsten case as the radiation shielding to protect medical staffs from the damage of radiation.

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