Characteristic X-ray flux from sealed Cr, Cu, Mo, Ag and W tubes

The flux of characteristic Kα radiation from sealed X-ray tubes with Cr, Cu, Mo, Ag and W targets is determined on an absolute scale by measuring integrated intensities of Bragg reflections from well characterized powder samples. The values of the flux are corrected for absorption in the tube target. The tube voltage is varied, and the flux is observed to vary as (U 0−1) p , where U 0 is the ratio of tube voltage to the excitation voltage of characteristic Kα radiation (over-voltage). The exponent p is very close to the theoretical value of 1.67 in the cases of Cr, Cu, Mo and Ag, while in the case of W the value of p is 1.45. The absolute values of the flux are close to the theoretical estimates of Green & Cosslett [Proc. Phys. Soc. (London) (1961), 78, 1206–1214] for Cr and Cu, 10 to 20% higher for Mo and Ag, but only about 1/3 of the calculated flux of W Kα radiation. This is due to an inadequate calculation of the indirect production of characteristic X-rays. A simple formula for the flux per unit solid angle is given in terms of the atomic number of the target, the tube voltage and the K excitation voltage.

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An Algorithm for the Description of White and Characteristic Tube Spectra (11 ≤ Z ≤ 83, 10keV ≤ Eo ≤ 50keV)

Advances in X-ray Analysis ◽

10.1154/s0376030800012908 ◽

1991 ◽

Vol 35 (B) ◽

pp. 721-726 ◽

Cited By ~ 2

Author(s):

H. Ebel ◽

H. Wiederschwinger ◽

J. Wernisch ◽

P.A. Pella

Keyword(s):

Kinetic Energy ◽

Cross Section ◽

Atomic Number ◽

Solid Angle ◽

Electron Interaction ◽

X Rays ◽

X Ray ◽

The Cross ◽

Spectral Responses ◽

The Continuum

Kramers described the cross section of electron interaction with target atoms of atomic number Z bywhere Eo is the kinetic energy of impinging electrons, and E o S) the energy of x-ray photons of the continuum, Smith et al modified this equation, introducing an exponent x, so thatWe applied the cross-section σS, E to the evaluation of experimental results. The evaluation of the measured spectral responses of the x-ray signals nE was performed bywhere f(deff) describes the absorption of x-rays of energy E in the target, RE accounts for backscattering of electrons, DE quantifies the efficiency of x-ray detection within the solid angle Ω.

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Parallel-beam X-ray diffractometry using X-ray guide tubes

Journal of Applied Crystallography ◽

10.1107/s0021889899015344 ◽

2000 ◽

Vol 33 (2) ◽

pp. 389-391 ◽

Cited By ~ 4

Author(s):

Toyoko Yamanoi ◽

Hiromoto Nakazawa

Keyword(s):

Large Diameter ◽

Preferred Orientation ◽

X Rays ◽

X Ray Diffraction ◽

Parallel Beam ◽

X Ray ◽

Orientation Effects ◽

Powder Samples ◽

Xrd Patterns ◽

Integrated Intensities

A parallel-beam X-ray diffraction geometry using X-ray guide tubes is proposed to eliminate preferred-orientation effects in powder X-ray diffraction (XRD) patterns and for new applications of XRD. A bundle of X-ray guide tubes (polycapillaries) is used to provide an intense quasi-parallel (approximately 0.2° divergence) and large-diameter (approximately 20 mm) beam of X-rays needed for parallel-beam diffractometry. Mica and silicon particles were agitated inside a cylindrical chamber by a steady flow of N2gas so that they were randomly oriented. The quasi-parallel incident X-ray beam passed through the cloud of floating particles. The diffracted X-rays were detected using a standard 2θ diffractometer. The integrated intensities observed agree well with those calculated from the known model of the crystal structure. This result demonstrates that this type of diffractometry is capable of avoiding preferred-orientation effects and of collecting XRD data for moving powder samples.

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High spatial resolution x-ray microanalysis of interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137793 ◽

1995 ◽

Vol 53 ◽

pp. 284-285

Author(s):

J. R. Michael

Keyword(s):

Spatial Resolution ◽

Electron Probe ◽

Solid Angle ◽

Collection Efficiency ◽

Spatial Scales ◽

Energy Dispersive Spectrometer ◽

X Rays ◽

X Ray ◽

Probe Size ◽

Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

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Contribution of x-ray total reflection to the background intensity in EPMA

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134600 ◽

1990 ◽

Vol 48 (2) ◽

pp. 202-203

Author(s):

Werner P. Rehbach ◽

Peter Karduck

Keyword(s):

Atomic Number ◽

Target Material ◽

Total Reflection ◽

Background Intensity ◽

X Rays ◽

Characteristic Radiation ◽

X Ray

In the EPMA of soft x rays anomalies in the background are found for several elements. In the literature extremely high backgrounds in the region of the OKα line are reported for C, Al, Si, Mo, and Zr. We found the same effect also for Boron (Fig. 1). For small glancing angles θ, the background measured using a LdSte crystal is significantly higher for B compared with BN and C, although the latter are of higher atomic number. It would be expected, that , characteristic radiation missing, the background IB (bremsstrahlung) is proportional Zn by variation of the atomic number of the target material. According to Kramers n has the value of unity, whereas Rao-Sahib and Wittry proposed values between 1.12 and 1.38 , depending on Z, E and Eo. In all cases IB should increase with increasing atomic number Z. The measured values are in discrepancy with the expected ones.

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Comparison of high-angle take-off and low-angle take-off EDX detector geometry of the HF-2000 FE-TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147107 ◽

1993 ◽

Vol 51 ◽

pp. 252-253

Author(s):

Y. Sato ◽

T. Hashimoto ◽

M. Ichihashi ◽

Y. Ueki ◽

K. Hirose ◽

...

Keyword(s):

Quantitative Analysis ◽

Field Emission ◽

Solid Angle ◽

Energy Dispersive ◽

Objective Lens ◽

X Rays ◽

High Angle ◽

X Ray ◽

Detector Geometry

Analytical TEMs have two variations in x-ray detector geometry, high and low angle take off. The high take off angle is advantageous for accuracy of quantitative analysis, because the x rays are less absorbed when they go through the sample. The low take off angle geometry enables better sensitivity because of larger detector solid angle.Hitachi HF-2000 cold field emission TEM has two versions; high angle take off and low angle take off. The former allows an energy dispersive x-ray detector above the objective lens. The latter allows the detector beside the objective lens. The x-ray take off angle is 68° for the high take off angle with the specimen held at right angles to the beam, and 22° for the low angle take off. The solid angle is 0.037 sr for the high angle take off, and 0.12 sr for the low angle take off, using a 30 mm2 detector.

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The sensitivity of atomic analysis by X-rays

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1932.0058 ◽

1932 ◽

Vol 135 (828) ◽

pp. 637-656 ◽

Cited By ~ 3

Keyword(s):

Atomic Number ◽

Target Material ◽

High Sensitivity ◽

Major Constituent ◽

X Rays ◽

Depth Of Penetration ◽

X Ray ◽

Constituent Element ◽

The Difference ◽

Atomic Analysis

In a previous paper it was shown that 0·0007 per cent, of 29 Cu and 0·0003 per cent, of 26 Fe could be detected in 30 Zn by atomic analysis by X-ray spectroscopy. This sensitivity is greater than that which was claimed by Noddack, Tacke, and Berg, who set the limit at about 0·1 per cent, for non-metals, and by Hevesy, who stated it to be about 0·01 per cent, for an element present in an alloy. It was later suggested by Hevesy that the high value of the sensitivity which we found might result from the fact that some of the alloys we had used were composed of elements of almost equal atomic number, and that the sensitivity would be smaller for a constituent of low atomic number mixed with a major constituent of high atomic number. To elucidate these disagreements we have made further observations of the sensitivity with elements of different atomic number and have investigated the conditions which can influence the sensitivity. The Factors Determining Sensitivity . The detection of one element in a mixture of elements depends upon the identification of its K or L lines in the general spectrum emitted by the mixture under examination. The intensity with which these lines are excited in the target (“excited intensity”) is proportional to the number of atoms of the constituent element excited, i. e ., to its concentration and to the volume of the target in which the cathode ray energy is absorbed. The depth of penetration of the cathode rays is determined by the density of the target material and by their velocity ( i. e ., by the voltage applied to the X-ray tube). Schonland has shown that the range of homogeneous cathode rays in different elements, expressed as a mass per unit area, is approximately constant and is independent of the atomic number of the absorbing element. When their velocity is increased, the cathode rays will penetrate to a greater depth, and therefore a greater number of atoms of all constituents will be ionised. This will increase the “excited intensity” of the lines due to the particular constituent sought equally with those lines of the other elements present. The intensity of a line further depends upon the difference between the voltage applied to the X-ray tube and that necessary to excite the series. For these reasons, a high applied voltage is required for a high sensitivity.

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New Rotating Anode X-Ray Generator For XAFS Experiments

Advances in X-ray Analysis ◽

10.1154/s0376030800022552 ◽

1995 ◽

Vol 39 ◽

pp. 149-153

Author(s):

Kenji Sakurai

Keyword(s):

High Vacuum ◽

Lanthanum Hexaboride ◽

X Rays ◽

Tube Voltage ◽

X Ray ◽

Low Tube Voltage ◽

Tube Current ◽

Sample Position ◽

Good Energy ◽

X Ray Absorption

A high-power X-ray generator equipped with a lanthanum hexaboride cathode has been developed for X-ray absorption fine structure experiments. A high tube-current of more than 1,000 mA can be provided when operated at low tube-voltage of less than 20 kV. In addition, the focal width is narrow enough (less than 0.1 mm) to ensure good energy resolution. Extremely intense monochromatic X-rays (106 ∼ 107 counts/(sec.mm2) at the sample position), which are completely free from higher order harmonics and tungsten contamination lines, are available, when a Johansson-type spectrometer is employed. The filament life has been significantly prolonged by the high vacuum specification of the tube.

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Light Element Analysis

Advances in X-ray Analysis ◽

10.1154/s0376030800011277 ◽

1969 ◽

Vol 13 ◽

pp. 26-48

Author(s):

A. K. Baird

Keyword(s):

Atomic Number ◽

Matrix Effects ◽

Light Element ◽

Electron Excitation ◽

Electron Gun ◽

X Rays ◽

Element Analysis ◽

X Ray ◽

High Emission ◽

Quantitative Analyses

Qualitative and quantitative analyses of elements below atomic number 20, and extending to atomic number 4, have been made practical and reasonably routine only in the past five to ten years by advances in: 1) excitation sources; 2) dispersive spectrometers; 3) detection devices; and 4) reductions of optic path absorption. At present agreement is lacking on the best combination of parameters for light element analysis. The principal contrasts in opinion concern excitation.Direct electron excitation, particularly as employed in microprobe analysis (but not limited to such instruments), provides relatively high emission intensities of all soft X-rays, but also generates a high continuum, requires the sample to be at essentially electron gun vacuum, and introduces practical calibration problems (“matrix effects“). X-ray excitation of soft X-rays overcomes some of the latter three disadvantages, and has its own limitations. Sealed X-ray sources of conventional or semi-conventional design can provide useful (if not optimum) light element emission intensities down to atomic number 9, hut with serious loss of efficiency in many applications below atomic number 15 largely because of window-thinness limitations under electron bombardment.

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X-ray emission analysis in the electron microscope

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1982.0050 ◽

1982 ◽

Vol 305 (1491) ◽

pp. 535-543 ◽

Cited By ~ 5

Keyword(s):

Electron Microscope ◽

Atomic Number ◽

Critical Examination ◽

X Rays ◽

Emission Analysis ◽

X Ray ◽

Analytical Precision

The technique by which sample-emitted X-rays are recorded in the electron microscope is assessed. Although the method is relatively insensitive for elements of low atomic number, its applicability in the field of s imultaneous structural and compositional investigations is discussed, together with a critical examination of the analytical precision possible. Various examples of its use are described, including some where structure and stoichiometry can be determined in crystals containing fewer than 10 10 atoms.

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Optimalisasi Penggunaan Variasi Filter Pada Pesawat Sinar-X Mobile Guna Mencapai Nilai Entrance Skin Exposure (Ese) Sesuai Organ Pemeriksaan

Prosiding SNFA (Seminar Nasional Fisika dan Aplikasinya) ◽

10.20961/prosidingsnfa.v5i0.46609 ◽

2020 ◽

Vol 5 ◽

Author(s):

Oki Dewi Pamungkas ◽

Utari Utari ◽

Suharyana Suharyana ◽

Riyatun Riyatun ◽

Nining Hargiani

Keyword(s):

Tolerance Limit ◽

Low Energy ◽

X Rays ◽

Tolerance Limits ◽

Tube Voltage ◽

X Ray ◽

Skin Exposure ◽

Measurement Results ◽

Irradiation Field ◽

Field Area

Abstract: This study was to determine the effect of variations in the type and thickness of the filter on the ESE and HVL values. The use of filters aims to eliminate low energy X-rays, increase effective energy, and reduce dose acceptance to patients. This variation of Al with Cu and Al with Zn filters uses a voltage (70, 80, and 90) kV, 20 mAs, 100 cm SSD, and an irradiation field area of 10 cm x 10 cm. The result of measuring the consistency of the X-ray tube voltage has the largest error value of 4.93%. At a voltage of 90 kV, the measurement results of the variation of Al filter with Cu thickness of 0.2 mm and 0.3 mm and Al filter with Zn thickness of 0.25 mm and 0.50 mm are within the tolerance limits of the thorax examination organ. While the measurement results of the Al filter variants with a Cu thickness of 0.4 mm and an Al filter with a Zn thickness of 0.75 mm are within the tolerance limit of the cranium examination organ. The ESE half value can use 3.03 mm Al, equivalent to 0.135 mm Cu or 0.22 mm Zn.Abstrak: Penelitian ini untuk mengetahui pengaruh variasi jenis dan ketebalan filter terhadap nilai ESE dan HVL. Penggunaan filter bertujuan untuk mengeliminasi sinar-X energi rendah, meningkatkan energi efektif, dan mengurangi penerimaan dosis pada pasien. Variasi filter Al dengan Cu dan Al dengan Zn ini menggunakan tegangan (70, 80, dan 90) kV, 20 mAs, SSD 100 cm, dan luas lapangan penyinaran 10 cm x 10 cm. Hasil pengukuran konsistensi tegangan tabung sinar-X memiliki nilai error terbesar 4,93%. Pada tegangan 90 kV hasil pengukuran variasi filter Al dengan Cu ketebalan 0,2 mm dan 0,3 mm dan filter Al dengan Zn ketebalan 0,25 mm dan 0,50 mm dalam batas toleransi organ pemeriksaan thorax. Sedangkan hasil pengukuran varisi filter Al dengan Cu ketebalan 0,4 mm dan filter Al dengan Zn ketebalan 0,75 mm dalam batas toleransi organ pemeriksaan cranium. Nilai setengah ESE dapat menggunakan 3,03 mm Al, setara dengan 0,135 mm Cu atau 0,22 mm Zn.

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