We demonstrate material phase retrieval by linearly translating extended polycrystalline samples along the symmetry axis of an annular beam of high-energy X-rays. A series of pseudo-monochromatic diffraction images are recorded from the dark region encompassed by the beam. We measure Bragg maxima from different annular gauge volumes in the form of bright spots in the X-ray diffraction intensity. We present the experiment data from three materials with different crystallographic structural properties i.e. near ideal, large grain size and preferred orientation. This technique shows great promise for analytical inspection tasks requiring highly penetrating radiation such as security screening, medicine and non-destructive testing.

We combine diffraction and absorption tomography by raster scanning samples through a hollow cone of pseudo monochromatic X-rays with a mean energy of 58.4 keV. A single image intensifier takes 90x90 (x,y) snapshots during the scan. We demonstrate a proofof-principle of our technique using a heterogeneous three-dimensional (x,y,z) phantom (90x90x170 mm 3 ) comprised of different material phases, i.e., copper and sodium chlorate. Each snapshot enables the simultaneous measurement of absorption contrast and diffracted flux. The axial resolution was ~1 mm along the (x,y) orthogonal scan directions and ~7 mm along the z-axis. The tomosynthesis of diffracted flux measurements enable the calculation of d-spacing values with ~0.1 Å full width at half maximum (FWHM) at ~2 Å. Thus the identified materials may be color-coded in the absorption optical sections. Characterization of specific material phases is of particular interest in security screening for the identification of narcotics and a wide range of homemade explosives concealed within complex "everyday objects." Other potential application areas include process control and biological imaging. IntroductionRadiographic imaging and the structural analysis of materials using X-rays developed disparately soon after the discovery of X-rays in 1895 [1]. The former has evolved from simple planar imaging into sophisticated tomographic methods [2,3], while the latter formed the basis of X-ray crystallography. Each approach demands quite different spatiotemporal collection and sensing requirements [4,5]. In general, incident X-rays composing a spatial image propagate along a linear path from the source to the detector and do not interact with the materials under inspection. However, the spectroscopic analysis of the transmitted X-rays may provide some useful materials discrimination information [6]. Ultimately, such approaches are limited fundamentally and cannot provide structural or 'molecular resolution' analysis. In contrast, determination of the atomic and molecular structure of crystalline/polycrystalline materials requires analysis of coherently scattered or diffracted Xrays from a sample. The relatively low energy of the interrogating radiation used in laboratory X-ray diffraction (XRD) limits penetration into the sample to near the incident surface. Significantly higher X-ray energies are required (i.e. an order of magnitude increase in photon energy over the legacy 8 keV Cu Kα [7]) for transmission mode diffraction for highly absorbing and or extended thickness samples [7][8][9]. Conventional fan beam tomography has provided diffracted flux measurements [5,[9][10][11] to demonstrate spatially-resolved material specific profiles. Novel compressive tomography promises further reductions in scan times and exposure [12][13][14]. The common problem confronting all volumetric XRD scanning/imaging methods is the production and measurement of sufficient diffracted flux or signal photons to provide the desired scan speed at application dependent energies. These consideration...

The reliability of both spacecraft as a whole and of their systems is confirmed at the stage of complex ground-based experimental tests, including complex thermal vacuum tests. The thermal state of the test object in thermal vacuum chambers is obtaining, in particular, using a solar simulator. Radiometers based on silicon photoelectric converters are most often used to control the irradiance of a solar simulator under conditions of thermal vacuum tests. At the same time, an analysis of the features of silicon photoelectric converters shows that their direct measurement with the accuracy required for ground-based tests of spacecraft is impossible; their output is nonlinear, depends on the received spectrum, their own temperature and has long-term instability. The achieved measurement accuracy directly depends on the number and accuracy of the tools used and the methods of the necessary correction, of which the mismatch correction between the solar simulator spectrum and the solar spectrum is the most difficult and laborious. At the same time, spectrally nonselective heat flux radiometers are free from the above disadvantages. In the course of the experiment we carried out, the significant dependence of the accuracy of measuring the irradiance with radiometers based on silicon photoelectric converters on the received spectrum was confirmed. The conclusion is made that direct measurement by heat flux radiometers of the irradiance of the solar simulator is most justified under the conditions of thermal vacuum tests.

ВИМІРЮВАННЯ ТОВЩИНИ ПЕРЕЗАРЯДНОЇ МІШЕНІ МОДИФІКОВАНИМ ЯДЕРНО-АНАЛІТИЧНИМ МЕТОДОМВиконано вимірювання товщини та однорідності по товщині тонкої самопідтримуючої вуглецевої плівки як перезарядної мішені для тандемного прискорювача. При вимірюваннях використовується неруйнівний ядерноаналітичний метод з прискореними до енергії 3,5 МеВ протонами. Метод було видозмінено з метою досягнення більшої точності, чутливості та розширення сфери застосування. У стандартну схему зворотного розсіяння іонів уводиться додатковий елемент -монітор-переривник пучка. Це змінює процедуру отримання експериментальних даних та спрощує формулу для розрахунків. Описано розроблені конструкції переривника та тримача мішеней. Товщина перезарядної мішені виявилася рівною в середньому 7,3 · 10 17 атомів/см 2 (~ 9,5 мкг/см 2 ). У порівнянні з оптимальною така товщина при прискоренні протонів є завеликою. Неоднорідність по товщині не перевищує похибку експерименту.Ключові слова: тандемний прискорювач, вуглецева перезарядна мішень, товщина плівки, спектрометрія зворотного розсіяння, видозмінений метод.

We introduce a new high-energy X-ray diffraction tomography technique for volumetric materials characterization. In this method, a conical shell beam is raster scanned through the samples. A central aperture optically couples the diffracted flux from the samples onto a pixelated energy-resolving detector. Snapshot measurements taken during the scan enable the construction of depth-resolved dark-field section images. The calculation of dspacing values enables the mapping of material phase in a volumetric image. We demonstrate our technique using five ~15 mm thick, axially separated samples placed within a polymer tray of the type used routinely in airport security stations. Our method has broad analytical utility due to scalability in both scan size and X-ray energy. Additional application areas include medical diagnostics, materials science, and process control.