scholarly journals X-ray mirror surface figure correction with nanometre precision controlled by layer stresses simulated by FEA

2019 ◽  
Vol 26 (1) ◽  
pp. 234-237 ◽  
Author(s):  
Xianchao Cheng ◽  
Lin Zhang
Keyword(s):  
Thermal Stresses ◽  
Surface Profile ◽  
Second Order ◽  
Surface Shape ◽  
X Rays ◽  
Mirror Surface ◽  
Step Size ◽  
Laser Applications ◽  
Element Analysis ◽  
X Ray

Hard X-rays with energies higher than several kiloelectronvolts can be focused to spot sizes below 10 nm with the present synchrotron beamlines, offering unique advantages for the chemical, elemental and structure analysis of matter. Nevertheless, a surface precision on the nanometre scale for the focusing optics is required and remains the main hurdle limiting X-ray analytical techniques with single-nanometre spatial resolution. On the other hand, to preserve the wavefront properties of coherent X-ray beams, precise control of the reflective mirror surface quality at the nanometre scale is demanded for X-ray free-electron laser applications. In this work, the surface shape of a multilayer-coated X-ray mirror is controlled by layer stresses. The desired surface profile of the mirror is differentiated to its second order to obtain its corresponding curvature profile. With a step size of 1 mm along the mirror length, different coating thicknesses are applied to create different layer thermal stresses from uniform temperature change. The mirror surface profile can be obtained by integrating the curvature profile to its second order and further corrected by moving constant values for the slope and height. The technical process is simulated by finite element analysis (FEA). A case study showed that the residual slope error and the residual height error between the desired shape and the FEA result are 0.22 µrad (r.m.s.) and 1.42 nm (r.m.s.), respectively.

HIGH-RESOLUTION PIXE USING BRAGG’S SPECTROMETER

1991 ◽  
Vol 01 (03) ◽  
pp. 251-258 ◽  
Author(s):  
M. TERASAWA
Keyword(s):  
High Resolution ◽  
Heavy Ions ◽  
X Rays ◽  
Light Elements ◽  
Element Analysis ◽  
X Ray ◽  
Peak Intensity ◽  
Moderate Energy ◽  
Practical Analysis ◽  
Wavelength Selectivity

K, L, and M X-rays in the wavelengths between 6Å and 130Å generated by the bombardment of 200 keV protons and other heavy ions were measured by means of a wavelength dispersive Bragg’s spectrometer. The X-ray peak intensity was fairly high in general, while the background was very low. The technique was favorably applied to a practical analysis of several light elements (Be, B, C, N, O, and F). Use of moderate-energy heavy ions considering the wavelength selectivity in X-ray generation was effective for the element analysis. The high-resolution spectrometry in the analytical application of ion-induced X-ray generation was found to be useful for the study of fine electronic structure, e.g. satellite and hypersatellite X-ray study, and of the chemical state of materials.

Light Element Analysis

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.

The Discovery of X-Rays: a Probable Case of Second Order Observation

2018 ◽  
Vol 19 (4) ◽  
pp. 403
Author(s):  
Marco Aurélio Clemente Gonçalves ◽  
Mariele Regina Pinheiro Gonçalves ◽  
Pablo Eduardo Ortiz
Keyword(s):  
History Of Science ◽  
Second Order ◽  
Point Of View ◽  
X Rays ◽  
Historical Reconstruction ◽  
X Ray ◽  
Probable Case ◽  
The Status ◽  
History Of

The discovery of x-rays, one of the most beautiful experiments ever carried out, generates numerous controversies and these, in turn, can trigger a series of counterproductive information regarding not only the History of Science but also the teaching  activity. The aim of this article is to resolve these controversies concerning what ocurred and highlight the important role of the German physicist Wilhelm Conrad Röntgen, highlighting not only his genius but, especially in this case in particular, his condition of second-order observer. It is not uncommon to find information in various media refering to this discovery under the claim that it was the result of a fortuitous event, and this denotes a profound lack of knowledge about the facts or a disrespect for the renowned discoverer. Such allegations about the event depreciate the extraordinary discovery that impacts humanity, from the deed  to the present. Thus, through a brief historical reconstruction, it was tried to present here what had happened judiciously. With this respect, the brilliant scientist is given the status of a second-rate observer, from the philosophical point of view. This condition resonates with the diachronic aspect of the History of Science, according to the perspective presented here, and it is also supported by the time taken by the discoverer from the beginning of his research until the end of it. Keywords: X-Ray. Second-Order Observer. History of Science. ResumoO descobrimento dos raios-x, um dos mais belos experimentos já realizados, gera inúmeras controvérsias e essas, por sua vez, podem desencadear uma série de informações contraproducentes no tangente não só a História da Ciência como também à atividade de ensino. O presente artigo tem como objetivo dirimir tais polêmicas com respeito ao ocorrido e destacar o importante papel do físico alemão Wilhelm Conrad Röntgen, destacando não só sua genialidade, mas sobretudo, neste caso em particular, a sua condição de observador de segunda ordem. Não é raro encontrar em diversos meios de comunicação informações com respeito a referida descoberta sob a alegação de que a mesma fora fruto de um caso fortuito e isso denota profundo desconhecimento sobre os fatos, ou então, desrespeito com o renomado descobridor. Tais alegações sobre o sucedido depreciam a descoberta extraordinária que impacta a humanidade, desde o feito até a atualidade. Assim, através de breve reconstrução histórica, buscou-se aqui apresentar o ocorrido criteriosamente. Com este respeito passa-se a atribuir ao brilhante cientista a condição de observador de segunda ordem, do ponto de vista filosófico. Tal condição encontra ressonância no aspecto diacrônico da História da Ciência, segundo a perspectiva aqui apresentada e está amparada, também, pelo tempo empreendido pelo descobridor desde o início de sua pesquisa até a finalização da mesma. Palavras-chave: Raios-x. Observador de Segunda Ordem. História da Ciência.

Compton Scattering Artifacts in Electron Excited X-Ray Spectra Measured with a Silicon Drift Detector

2011 ◽  
Vol 17 (6) ◽  
pp. 903-910 ◽  
Author(s):  
Nicholas W.M. Ritchie ◽  
Dale E. Newbury ◽  
Abigail P. Lindstrom
Keyword(s):  
Trace Element ◽  
Compton Scattering ◽  
Trace Element Analysis ◽  
X Rays ◽  
Silicon Drift Detector ◽  
Element Analysis ◽  
X Ray ◽  
Peak Absorption ◽  
Small Feature ◽  
Nonideal Behavior

AbstractArtifacts are the nemesis of trace element analysis in electron-excited energy dispersive X-ray spectrometry. Peaks that result from nonideal behavior in the detector or sample can fool even an experienced microanalyst into believing that they have trace amounts of an element that is not present. Many artifacts, such as the Si escape peak, absorption edges, and coincidence peaks, can be traced to the detector. Others, such as secondary fluorescence peaks and scatter peaks, can be traced to the sample. We have identified a new sample-dependent artifact that we attribute to Compton scattering of energetic X-rays generated in a small feature and subsequently scattered from a low atomic number matrix. It seems likely that this artifact has not previously been reported because it only occurs under specific conditions and represents a relatively small signal. However, with the advent of silicon drift detectors and their utility for trace element analysis, we anticipate that more people will observe it and possibly misidentify it. Though small, the artifact is not inconsequential. Under some conditions, it is possible to mistakenly identify the Compton scatter artifact as approximately 1% of an element that is not present.

Thermal and Electromigration Strain Distributions in 10 μm-Wide Aluminum Conductor Lines Measured by X-Ray Microdiffraction

1997 ◽  
Vol 473 ◽  
Author(s):  
P.-C. Wang ◽  
G. S. Cargill ◽  
I. C. Noyan ◽  
E. G. Liniger ◽  
C.-K. Hu ◽  
...  
Keyword(s):  
Thermal Stresses ◽  
Stress Gradient ◽  
Thermal Strain ◽  
Sample Surface ◽  
X Rays ◽  
Strain Measurements ◽  
X Ray ◽  
Glass Capillaries ◽  
Reflection Geometry ◽  
Made In

ABSTRACTX-ray microdiffraction was applied to study the thermal and electromigration strains in 10 μm-wide Al conductor lines with 10 μm spatial resolution. X-rays were collimated either by pinholes or by tapered glass capillaries to form x-ray microbeams. Measurements were made in a symmetric-reflection geometry so that the strains normal to the sample surface could be examined at different positions along the conductor lines. Results of thermal strain measurements show that the SiO2 passivation plays an important role in limiting relaxation of in-plane compressive thermal stresses in the Al lines, but that the passivation is not effective in confining the overall thermal expansion of the Al line along the film normal. Electromigration strain measurements show that a linear stress gradient developed within the first hour of electromigration. The magnitude of the stress gradient changed little until fast stress relaxations occurred near the anode end of the line. Possible mechanisms are discussed in light of these observations.

Investigation of Elemental Analysis of Water Samples by Radioalpha Induced X-Ray Emission Spectroscopy*

1974 ◽  
Vol 18 ◽  
pp. 333-342
Author(s):  
R. Hight ◽  
C. C. Foster
Keyword(s):  
Water Samples ◽  
Background Radiation ◽  
Trace Element Analysis ◽  
Alpha Particles ◽  
Particle Accelerators ◽  
X Rays ◽  
Element Analysis ◽  
Worst Case ◽  
Helium Atmosphere ◽  
X Ray

AbstractAlpha particles and protons from charged particle accelerators and photons from both x-ray tubes and radioactive sources have been shown to be useful for the excitation of characteristic x-rays for multi-element energy dispersive trace analysis of environmental samples to the few ppm range. We have investigated the use of 4.5 MeV alpha particles from a thin window Po-210 source of 5 mCi effective strength to directly excite x-rays from trace elements in 1 cc water samples evaporated on 1.75 mg/cm2 thick mylar backings in a helium atmosphere in a lucite enclosure. Minimum detectable amounts (MDA's) were established for 19 elements (22 ≤ Z ≤ 82) using K-, L- and M- radiation and 50 minute counting times. The smallest MDA determined was 0.11 μg for vanadium. Other representative MDA's, in μg, are Fe-0.54, Mo-0.31 and Pb-0.43. MDA's lower by an average factor of about 10 over an eight month source life would result from the use of 1 Ci of Po-210 for 50 minutes per sample. Thinner sample backings and improved source encapsulation will reduce background radiation and further improve sensitivity. Comparison of our MDA's (5 mCi-Po-210) with those of Blasius et al., who used radiophoton sources and 40,000 sec. counting times to determine trace metal pollutants in water samples, shows radioalpha excitation to have comparable sensitivity in the worst case, arsenic and better, by more than two orders of magnitude, sensitivity in the best case, vanadium.Radioalpha induced x-ray trace element analysis offers the same advantages of portability, ease of operation, low maintenance and cost, and "in house" availability as radiophoton induced analysis. Because of the availability of more intense sources (up to 10 Ci), the fact that the detected radiation (x-rays) differs from the excitation radiation (a-particles) and that K, L, and M x-ray emission cross-sections depend essentially only on the emitted x-ray energy, lower MDA's are obtainable for many elements in thin samples for comparable counting times, as well.

Effect of X-ray Tube Window Thickness on Detection Limits for Light Elements in XRF Analysis

1994 ◽  
Vol 38 ◽  
pp. 299-305
Author(s):  
Daniel J. Whalen ◽  
D. Clark Turner
Keyword(s):  
Light Element ◽  
Detection Limits ◽  
X Rays ◽  
Light Elements ◽  
Absorption Data ◽  
Element Analysis ◽  
X Ray ◽  
Data Compilation ◽  
Beryllium Window ◽  
X Ray Background

Abstract Widespread interest in light element analysis using XRF has stimulated the development of thin x-ray tube windows. Thinner windows enhance the soft x-ray output of the tube, which more efficiently excite the light elements in the sample. A computer program that calculates the effect of window thickness on light element sample fluorescence has been developed. The code uses an NIST algorithm to calculate the x-ray tube spectrum given various tube parameters such as beryllium window thickness, operating voyage, anode composition, and take-off angle. The interaction of the tube radiation with the sample matrix is modelled to provide the primary and secondary fluorescence from the sample. For x-rays in the energy region 30 - 1000 eV the mass attenuation coefficients were interpolated from the photo absorption data compilation of Henke, et al. The code also calculates the x-ray background due to coherent and incoherent scatter from the sample, as well as the contribution of such scatter to the sample fluorescence. Given the sample fluorescence and background the effect of tube window thickness on detection limits for light elements can be predicted.

Thermal Stresses in Passivated Copper Interconnects Determined by X-Ray Analysis and Finite Element Modeling

1994 ◽  
Vol 338 ◽  
Author(s):  
R.P. Vinci ◽  
E.M. Zielinski ◽  
J.C. Bravman
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Thermal Stresses ◽  
Hydrostatic Stress ◽  
Fiber Texture ◽  
Copper Interconnects ◽  
Mechanical Anisotropy ◽  
X Rays ◽  
X Ray ◽  
Lift Off

ABSTRACTStresses in passivated copper lines were determined from strains measured using x-ray methods and compared to stresses calculated using finite element methods. Copper lines, 2 µm wide by 0.8 µm thick, were fabricated by DC magnetron sputtering and lift off patterning. The cross section of these lines was trapezoidal, with approximately 50° sidewalls. One set of samples was left bare, the others passivated with Si3N4 in several different thicknesses. Strain was determined using x-rays. Stress was calculated using elastic moduli adjusted for predominantly (111) fiber texture. Elastic-plastic finite element models provided comparisons of the effects of passivation thickness, rectangular and trapezoidal cross section, and mechanical anisotropy due to preferred texture on the hydrostatic stress in a line. A similar model for aluminum also provided a comparison case of stress as a function of passivation thickness.

scholarly journals Second order reflection from crystals used in soft X-ray spectroscopy

Nukleonika ◽  
2015 ◽  
Vol 60 (2) ◽  
pp. 263-265
Author(s):  
Ireneusz Książek
Keyword(s):  
Proportional Counter ◽  
Low Voltage ◽  
Pulse Height ◽  
Line Emission ◽  
Second Order ◽  
X Rays ◽  
X Ray ◽  
First Order ◽  
Order Reflection

Abstract In this note the ratio of the second to the first order reflection is determined for the KAP and PbSt crystals, for wavelengths corresponding to the Al K-line emission. The source of the radiation was a low-voltage stabilized X-ray tube. The X-rays were detected with a Bragg spectrometer equipped with a proportional counter detector. The signal measured by the proportional counter was subsequently pulse height analyzed.

scholarly journals Energy-dispersive X-ray diffraction mapping on a benchtop X-ray fluorescence system

2014 ◽  
Vol 47 (2) ◽  
pp. 488-494 ◽  
Author(s):  
David W. Lane ◽  
Antony Nyombi ◽  
James Shackel
Keyword(s):  
Low Power ◽  
Energy Dispersive ◽  
Characteristic Line ◽  
X Rays ◽  
X Ray Diffraction ◽  
Step Size ◽  
X Ray ◽  
Hyper Spectral ◽  
Fluorescence Spectrometer ◽  
Polished Metal

A method for energy-dispersive X-ray diffraction mapping is presented, using a conventional low-power benchtop X-ray fluorescence spectrometer, the Seiko Instruments SEA6000VX. Hyper spectral X-ray maps with a 10 µm step size were collected from polished metal surfaces, sectioned Bi, Pb and steel shot gun pellets. Candidate diffraction lines were identified by eliminating those that matched a characteristic line for an element and those predicted for escape peaks, sum peaks, and Rayleigh and Compton scattered primary X-rays. The maps showed that the crystallites in the Bi pellet were larger than those observed in the Pb and steel pellets. The application of benchtop spectrometers to energy-dispersive X-ray diffraction mapping is discussed, and the capability for lower atomic number and lower-symmetry materials is briefly explored using multi-crystalline Si and polycrystalline sucrose.

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