Journal articles: 'X-rays generator'

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Wilke, Markus, Karsten Harnisch, Wolfram Knapp, Martin Ecke, and Thorsten Halle. "Focusing of x-rays emitted by a pyroelectric x-ray generator for micro x-ray fluorescence." Journal of Vacuum Science & Technology B 37, no. 1 (January 2019): 011203. http://dx.doi.org/10.1116/1.5067322.

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Sakurai, Kenji. "New Rotating Anode X-Ray Generator For XAFS Experiments." Advances in X-ray Analysis 39 (1995): 149–53. http://dx.doi.org/10.1154/s0376030800022552.

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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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ENDO, Satoru, Masaharu HOSHI, Jun TAKADA, Toshihiro TAKATSUJI, Yosuke EJIMA, Shin SAIGUSA, Akira TACHIBANA, and Masao S. SASAKI. "Development, Beam Characterization and Chromosomal Effectiveness of X-rays of RBC Characteristic X-ray Generator." Journal of Radiation Research 47, no. 2 (2006): 103–12. http://dx.doi.org/10.1269/jrr.47.103.

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Hasegawa, Hiroaki, and Masanori Sato. "Acquisition of Quasi-Monochromatic Dual-Energy in a Microfocus X-ray Generator and Development of Applied Technology." Diagnostics 9, no. 1 (March 4, 2019): 27. http://dx.doi.org/10.3390/diagnostics9010027.

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In regenerative medicine, evaluation of bone mineral density using a microfocus X-ray generator could eventually be used to determine the degree of bone tissue regeneration. To evaluate bone mineral density against regenerated bone material, two low-energy X-rays are necessary. Herein, the acquisition of quasi-monochromatic, dual-energy soft X-ray and the subsequent medical application were examined using the K-absorption edges of two types of metal filters (i.e., zirconium and tin) in a microfocus X-ray generator. Investigation of the optimal tube voltage and filter thickness to form a quasi-monochromatic energy spectrum with a single filter revealed that a filter thickness of 0.3 mm results in an optimal monochromatization state. When a dual filter was used, the required filter thickness was 0.3 mm for tin and 0.2 mm for zirconium at a tube voltage of 35 kV. For the medical application, we measured quasi-monochromatic, dual-energy X-rays to evaluate the measurement accuracy of bone mineral density. Using aluminum as a simulated bone sample, a relative error of ≤5% was consistent within the aluminum thickness range of 1–3 mm. These data suggest that a bone mineral density indicator of recycled bone material can be easily obtained with the quasi-monochromatic X-ray technique using a microfocus X-ray generator.

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Kitaguchi, Takao, Asami Hayato, Wataru Iwakiri, Yoko Takeuchi, Megu Kubota, Kazuki Nishida, Teruaki Enoto, and Toru Tamagawa. "Development of the GEM-TPC X-ray Polarimeter with the Scalable Readout System." EPJ Web of Conferences 174 (2018): 01015. http://dx.doi.org/10.1051/epjconf/201817401015.

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We have developed a gaseous Time Projection Chamber (TPC) containing a single-layered foil of a gas electron multiplier (GEM) to open up a new window on cosmic X-ray polarimetry in the 2–10 keV band. The micro-pattern TPC polarimeter in combination with the Scalable Readout System produced by the RD51 collaboration has been built as an engineering model to optimize detector parameters and improve polarimeter sensitivity. The polarimeter was characterized with unpolarized X-rays from an X-ray generator in a laboratory and polarized X-rays on the BL32B2 beamline at the SPring-8 synchrotron radiation facility. Preliminary results show that the polarimeter has a comparable modulation factor to a prototype of the flight one.

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Duarte, Raghunatha Faria, Bruno Andrade de Oliveira, and Euzebio De Sousa. "MODELAGEM ELÉTRICA DOS TUBOS DE RAIOS-X UTILIZADOS EM SISTEMAS DE FLUOROSCOPIA COM O OBJETIVO DE MINIMIZAR A RADIAÇÃO TRANSMITIDA AO PACIENTE." e-xacta 10, no. 1 (May 31, 2017): 53. http://dx.doi.org/10.18674/exacta.v10i1.2141.

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A finalidade deste artigo foi demonstrar os processos e parâmetros e que são necessários para o funcionamento do tudo de raios-X na utilização em técnica de fluoroscopia, abordou-se a parte construtiva do Gerador de alta tensão e do tubo de raios-X e a forma de como ocorre a liberação dos raios-X que incide ao paciente durante o exame, a condição de como a corrente e a diferença de potencial geram os raios-X que incide ao paciente durante o procedimento e o que uma exposição desnecessária a tais raios pode ser prejudicial em quantidades que não agregam imagem ao exame, desta forma criou-se uma proposta de modelagem elétrica de um tubo de raios-X em que abordou uma alternativa para minimizar a radiação que atravessa ao paciente sem a geração de imagem útil.ABSTRACT<pre>The purpose of this article was to demonstrate the processes and parameters that are necessary for the operation of all X-rays in the use in fluoroscopy technique, the constructive part of the High Voltage Generator and the X-ray tube and the How the X-ray release occurs to the patient during the examination, the condition of how the current and potential difference generates the X-rays incident to the patient during the procedure and what unnecessary exposure to such rays May be detrimental in amounts that do not add an image to the examination. In this way, a proposal was made for the electric modeling of an X-ray tube, in which it addressed an alternative to minimize the radiation that passes through the patient without generating useful images.</pre>

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Sơn, Nguyễn An, Hai Van Cao, Trieu Ngoc Le, Giang Van Nguyen, Ha Thi Nguyet Nguyen, Quynh Ngoc Dieu Tran, Tien Nguyen Thuy Bui, and Duc Doan Dinh Le. "Assessment of aerobic bacteria killing activity of low energry X-rays in potatoes." Science and Technology Development Journal - Natural Sciences 5, no. 3 (May 7, 2021): first. http://dx.doi.org/10.32508/stdjns.v5i3.1040.

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Potato is one of popular agricultural products grown and used in the world with high effective economic and nutritional value. In potatoes, there are always have some harmful bacteria species due to the sources of exposure from the seed, soil as well as the post-harvest environment which make deceasing the quality and quantity of potatoes. Usually, irradiation with gamma isotope sources is used in food irradiation, however, the disadvantage of the gamma source is the safe shielding reason even without the use of irradiation. Nowadays, X-ray irradiation in food is one of the methods interest to storage in long time. The first advantage of X-ray irradiation is that most of aerobic bacteria in food is killed, but does it not change the quality of the potato. Moreever, the advantage of an X-ray generator is that it does not have to cover up radiation when not in use. In this study, we have used low energy X-rays emitted from X-ray generator MBR-1618R-BE (Hitachi -Japan) to study the ability to kill aerobic bacteria in potatoes grown in Da Lat. After preparation, potato samples were irradiated at doses ranging from 50 Gy to 5000 Gy. The irradiated samples were homogenized and inoculated on Nutrient Agar and incubated at 370C in an incubator to check the changes of aerobic bacteria. The research showed that the number of aerobic bacteria decreased dramatically to a dose of 1000 Gy (the aerobic bacteria was only less than 0,6%), despite a sharp increase in the dose of irradiation, this number decreased a little. The results also showed that D10 dose was 471,34 Gy.

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Barkan, Shaul, Valeri D. Saveliev, Jan S. Iwanczyk, Liangyuan Feng, Carolyn R. Tull, Bradley E. Patt, Dale E. Newbury, John A. Small, and Nestor J. Zaluzec. "A New Improved Silicon Multi-Cathode Detector (SMCD) for Microanalysis and X-Ray Mapping Applications." Microscopy Today 12, no. 6 (November 2004): 36–37. http://dx.doi.org/10.1017/s1551929500065962.

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A silicon multi-cathode detector (SMCD) has been developed for microanalysis and x-ray mapping applications. The SMCD has a large active area (∼0.5 cm2), excellent energy resolution, and high count rate capability. The detector utilizes novel structures that have produced very low dark current, high electric field, uniform charge collection, low noise and high sensitivity to low energy x-rays. The detector's spectral response was evaluated using a 55Fe radioisotope source, as well as by fluorescing materials with an x-ray generator. Figure 1 shows a 55Fe spectrum with an energy resolution of 125 eV FWHM at 5.9 keV collected at 12 μs peaking time. This energy resolution has been repeatably measured on many different detectors. To evaluate the high count rate x-ray performance, which is very important for fast x-ray mapping, a Cu sample was fluoresced using a Rh-anode x-ray tube.

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Faenov, A. Ya, T. A. Pikuz, S. A. Magnitskiy, N. Nagorskiy, M. Tanaka, M. Ishino, M. Nishikino, et al. "X-ray coherent mirage: Generation of phase – matched coherent point source in plasma media by propagated X-ray laser seeded beam." Laser and Particle Beams 34, no. 3 (May 30, 2016): 402–11. http://dx.doi.org/10.1017/s0263034616000288.

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AbstractThe overview of the recent results for discovery and investigations of a very exotic phenomenon – optical mirage in the X-ray spectral range – is presented. It was found that the mirage could be created in the form of coherent virtual point source, emerging in the vicinity of the second plasma in two-stage oscillator-amplifier X-ray laser. The X-ray source-mirage, rigidly phased with the initial radiation of generator, occurs only when amplification takes place in the amplifier plasma and leads to the appearance of the interference pattern in the form of concentric rings in the spatial profile of the output X-ray laser beam. The equation describing the emergence of X-ray mirage was found, numerical solution of which shows that its formation is similar to that of the optical mirages observed at propagation of light rays through an inhomogeneously heated air. Obtained results have already demonstrated novel comprehension into the physical nature of amplification of X-ray radiation, opening additional opportunities for X-ray interferometry, holography, and other applications, which require multiple rigidly phased sources of coherent radiation.

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Levine, Lance, and Marc Levine. "DRRGenerator: A Three-dimensional Slicer Extension for the Rapid and Easy Development of Digitally Reconstructed Radiographs." Journal of Clinical Imaging Science 10 (October 29, 2020): 69. http://dx.doi.org/10.25259/jcis_105_2020.

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As the interest in image-guided medical interventions has increased, so too has the necessity for open-source software tools to provide the required capabilities without exorbitant costs. A common issue encountered in these procedures is the need to compare computed tomography (CT) data with X-ray data, for example, to compare pre-operative CT imaging with intraoperative X-rays. A software approach to solve this dilemma is the production of digitally reconstructed radiographs (DRRs) which computationally simulate an X-ray-type image from CT data. The resultant image can be easily compared to an X-ray image and can provide valuable clinical information, such as small anatomical changes that have occurred between the pre-operative and operative imaging (i.e., vertebral positioning). To provide an easy way for clinicians to make their own DRRs, we propose DRR generator, a customizable extension for the open-source medical imaging application three-dimensional (3D) Slicer. DRR generator provides rapid computation of DRRs through a highly customizable user interface. This extension provides end-users a free, open-source, and reliable way of generating DRRs. This program is integrated within 3D Slicer and thus can utilize its powerful imaging tools to provide a comprehensive segmentation and registration application for clinicians and researchers. DRR generator is available for download through 3D Slicer’s in-app extension manager and requires no additional software.

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Kim, Young-Pyo, Tae-Gon Kim, Yong-Pil Park, and M. in-Woo Cheon. "Output Characteristics of Mobile X-Rays Using a High Voltage Generator of Pulse Frequency Modulation." International Journal of Multimedia and Ubiquitous Engineering 11, no. 1 (January 31, 2016): 319–26. http://dx.doi.org/10.14257/ijmue.2016.11.1.30.

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Kovalchuk, B. M., A. A. Zherlitsyn, and N. V. Tsoy. "Plasma-filled diode with a rod anode for repetitive pulsed X-ray sources." Laser and Particle Beams 34, no. 4 (September 26, 2016): 631–36. http://dx.doi.org/10.1017/s0263034616000574.

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AbstractThe paper presents a cylindrical diode with a rod anode for repetitive pulsed intense X-ray sources. The diode uses a massive anode of diameter 1 cm, thus increasing the lifetime of the energy converter. The diode gap is preliminary filled with ions produced by cathode flare in a vacuum discharge, allowing electron beam pinching at a voltage of <200 kV. In the mode of pinching, the diode is an efficient source of high-power X rays. At a distance of 20 cm from the X-ray source, the radiation dose per pulse is 0.4 R at a peak power of 7 × 106 R/s. The full-width at half-maximum of the radiation pulse is 40 ns. The power in the diode is 1.8 GW at a beam current of 10 kA and exceeds the maximum power of the generator operating onto a matched load with constant resistance.

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Vujosevic, Bozica, and Bojana Bokorov. "Radiotherapy: Past and present." Archive of Oncology 18, no. 4 (2010): 140–42. http://dx.doi.org/10.2298/aoo1004140v.

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Discovery of radioactive X-rays in 1895 by Wilhelm Conrad Roentgen marked the beginning of significant events in diagnostics and treatment of many diseases. The idea of using X-rays in treatment of malignant diseases was born the same year, when X rays were used for treatment of local relapse of breast cancer, upon initiative of medical student Emil Grubbe. This event was followed by important discoveries of radioactive elements. Marie and Pierre Curie discovered polonium and radium and were awarded the Nobel Prize for their discovery in 1903 and 1911. Their daughter, Ir?ne Curie, joined their research on radioactivity and was awarded the Nobel Prize in 1935. The potentials of radiotherapy became increasingly exploited in treatment of oncological patients. The beginning of radiotherapy in Novi Sad dates from 1934 with the arrival of Dr. Nikola Vujic, a specialist in internal medicine and radiology, and when the first universal X-ray generator was installed and used for therapy. After the World War II, radiotherapy was modernized by purchasing modern devices: 4-valve multi-voltage device (Siemens) for deep radiotherapy and contact radiotherapy by Chaoul. Today, radiotherapy for oncological patients in Novi Sad complies with modern trends and protocols (conformal technique). It has the most advanced technical capacities used worldwide and it takes into account the therapeutical effects and patients' quality of life.

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Zhang, Cheng, Victor F. Tarasenko, Tao Shao, Evgeni Kh Baksht, Alexander G. Burachenko, Ping Yan, and Igor' D. Kostyray. "Effect of cathode materials on the generation of runaway electron beams and X-rays in atmospheric pressure air." Laser and Particle Beams 31, no. 2 (May 29, 2013): 353–64. http://dx.doi.org/10.1017/s0263034613000116.

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AbstractIn this work, experiments were performed to study the effect of cathode materials on the amplitude of the super-short avalanche electron beam (SAEB) current and X-ray density during discharges in atmospheric-pressure air. In the experiments, discharges were generated by three nanosecond-pulse generators in air gaps between a plane anode and a tubular cathode made of different metals. The output pulse of the three generators had a rise time of 0.3, 1, 15 ns, and a full width at half maximum of 1, 2, 30–40 ns, respectively. For the generators with pulse rise-time of 0.3 and 1 ns, the cathodes used in these experiments were made of stainless steel, permalloy, titanium, niobium, copper, brass, and aluminum. For the generator with pulse rise-time of 15 ns, the cathodes were made of stainless steel, titanium, copper, and aluminum. When the rise time of the applied pulse is 0.3 ns, our experimental results show that the amplitude of the voltage across the gap depends on the cathode material and reaches its maximum value when a stainless steel cathode is used. It is also observed that, under such situation, the maximum amplitudes of the SAEB current occur at maximum voltages across the gap when all other factors are equal. Furthermore, the amplitude of the SAEB current hereof is found to depend not only on the material of the sharp edge of the tubular cathode, but also on the material of the side surface of the tubular cathode. When the rise time of the applied pulse is 1 ns, the experimental results show that the average number of electrons in SAEB is also affected by the cathode materials. In addition, in the case that the rise time of the voltage pulse is 15 ns and the gap spacing is 8 cm, the experimental results show that the cathode material has no effect on the voltage amplitude across the gap and the X-ray density. The increase of the pulse repetition frequency from 250 to 500 Hz under such condition can lead to a three-fold increase in X-ray density in a repetitive pulsed mode.

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Del Campo, Mark, Angela Criswell, and Katsunari Sasaki. "Fast SAXS data at home--Your personal SAXS beamline." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C411. http://dx.doi.org/10.1107/s2053273314095886.

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Small angle X-ray scattering (SAXS) is a useful technique for extracting structural information from biological samples in solution. Our SAXS instrument, the BioSAXS-1000, combines Kratky collimation with confocal optics to achieve maximum X-ray flux on the sample without beam shape corrections. Recently, we offered three new upgrades to the BioSAXS-1000: (1) 2.3 times more flux with the OptiSAXS optic, (2) automatic sample loading, and (3) automatic data analysis. Here, we evaluate the quality of SAXS data collected in short exposure times on the BioSAXS-1000 with these 3 upgrades by using X-rays supplied by an FR-X rotating anode X-ray generator. We measured a concentration series for each of several protein standards (lysozyme, HSA, etc.). Our results show that 1-minute exposures were sufficient to determine the basic structural parameters: radius of gyration, extrapolated intensity at zero angle, and molecular weight. The upgraded BioSAXS-1000 provides a beamline experience in the home laboratory.

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Lake, George, and R. E. Pudritz. "Ultra-High Energy Cosmic Ray Production by Current Disruption in Active Galactic Nuclei." Symposium - International Astronomical Union 107 (1985): 471–73. http://dx.doi.org/10.1017/s0074180900075951.

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Electrodynamic models for the activity of galactic nuclei are shown to be current systems which can be examined in terms of equivalent circuits. The resulting inductive circuit which describes the coupling of the generator (black-hole and accretion disk) to the distant load (jet plasma) is prone to various instabilities. We consider the disruption of this current system and propose that ultra-energetic cosmic rays (E~1019–1021 eV) could be produced during the discharges, which occur at distances of ~1016–1018 cm from the central massive hole (M~108 M). Such discharges will also produce variable γ-ray and X-ray activity and we discuss observations of Cen A in this regard.

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Cann, George H., Anthony Bourached, Ryan-Rhys Griffths, and David G. Stork. "Resolution enhancement in the recovery of underdrawings via style transfer by generative adversarial deep neural networks." Electronic Imaging 2021, no. 14 (January 18, 2021): 17–1. http://dx.doi.org/10.2352/issn.2470-1173.2021.14.cvaa-017.

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We apply generative adversarial convolutional neural networks to the problem of style transfer to underdrawings and ghost-images in x-rays of fine art paintings with a special focus on enhancing their spatial resolution. We build upon a neural architecture developed for the related problem of synthesizing high-resolution photo-realistic image from semantic label maps. Our neural architecture achieves high resolution through a hierarchy of generators and discriminator sub-networks, working throughout a range of spatial resolutions. This coarse-to-fine generator architecture can increase the effective resolution by a factor of eight in each spatial direction, or an overall increase in number of pixels by a factor of 64. We also show that even just a few examples of human-generated image segmentations can greatly improve—qualitatively and quantitatively—the generated images. We demonstrate our method on works such as Leonardo’s Madonna of the carnation and the underdrawing in his Virgin of the rocks, which pose several special problems in style transfer, including the paucity of representative works from which to learn and transfer style information.

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Kim, Tae-Gon, Min-Woo Cheon, and Yong-Pil Park. "Comparison of Output and Radiation Quality of X-rays according to the Full-Wave Rectification Method and Dual-Voltage Rectification Method of an X-ray Generator." Journal of the Korean Institute of Electrical and Electronic Material Engineers 23, no. 7 (July 1, 2010): 534–38. http://dx.doi.org/10.4313/jkem.2010.23.7.534.

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Jackson, M. C., R. D. Long, D. Lee, and N. J. Freeman. "Development of X-ray streak camera electronics at AWRE." Laser and Particle Beams 4, no. 1 (February 1986): 145–56. http://dx.doi.org/10.1017/s0263034600001695.

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The paper reviews a number of X-ray streak cameras developed at AWRE. These cameras are used to provide temporal and one-dimensional spatial or spectral information on X-rays emitted from laser produced plasmas. Two of these cameras have been designed to be combined with other diagnostic instrumentation; one with a Wolter X-ray microscope (×22 magnification) and the other with a Bragg diffraction crystal spectrometer. This latter instrument provides a few eV spectral resolution and ∼15 ps temporal resolution; a typical experimental application at the AWRE HELEN laser facility will be described. The paper describes the circuitry of the bipolar avalanche transistor ramp generator used to drive the streak plates of the cameras. Improvements to this include: (a) increasing the fastest streak rate to ∼10 ps mm−1 by a distributed capacitance network across each of the bipolar stacks of transistors, and (b) reducing the trigger jitter to approximately ±10 ps by the use of a new mix of transistors in the stack and a Raytheon RS 3500 avalanche transistor. Additional improvements have now been added. These include a ‘half-scan’ user facility to aid initial camera timing and direct switching to select the sweep rate of the camera.

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Komarskiy, Alexander Alexandrovich, Sergey Romanovich Korzhenevskiy, Andrey Viktorovich Ponomarev, and Nikita Alexandrovich Komarov. "Pulsed X-ray source with the pulse duration of 50 ns and the peak power of 70 MW for capturing moving objects." Journal of X-Ray Science and Technology 29, no. 4 (July 27, 2021): 567–76. http://dx.doi.org/10.3233/xst-210873.

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BACKGROUND: Traditionally, X-ray systems for capturing moving objects consist of a continuous X-ray source and a detector that operates at a predetermined frame rate. OBJECTIVE: This study investigates the possibility of using pulsed X-ray source with an inductive energy storage device and a semiconductor opening switch for shooting moving objects. METHODS: The study uses a high-voltage pulse generator that has the following parameters namely, the pulse voltage amplitude up to 320 kV, the pulse current up to 240 A, the current pulse duration of about 50 ns, and the pulse repetition rate up to 2 kHz. The duration and intensity of glow for standard CsI:Tl and Gd2O2S:Tb X-ray phosphors after their irradiation with X-ray flashes of about 50 ns duration are investigated. After X-ray radiation is converted into light, the signal is recorded using semiconductor detectors. We acquired several images of an object moving at a speed of about 20 m/s. A semiconductor detector with phosphor, which operates in the mode of continuous signal accumulation, is used. RESULTS: When using the pulsed X-ray source and phosphors with a short afterglow, the individual frames can be obtained at the pulse repetition rate of several kilohertz, and the detector does not contain the residual luminescence from the previous frame by the arrival of the next frame. CONCLUSIONS: The X-ray source shows good pulse-to-pulse reproducibility of X-rays, and can be used to capture objects in motion at a frame rate of several kHz.

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Shrestha, I., V. L. Kantsyrev, A. S. Safronova, A. A. Esaulov, K. M. Williamson, N. D. Ouart, G. C. Osborne, M. E. Weller, and M. F. Yilmaz. "Investigation of characteristics of hard x-rays produced during implosions of wire array loads on 1.6 MA Zebra generator." High Energy Density Physics 6, no. 1 (January 2010): 113–20. http://dx.doi.org/10.1016/j.hedp.2009.09.001.

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Dias, João M., Sergey Bursakov, Carla Carneiro, José J. G. Moura, Isabel Moura, and Maria João Romão. "Crystallization and preliminary X-ray analysis of a nitrate reductase from Desulfovibrio desulfuricans ATCC 27774." Acta Crystallographica Section D Biological Crystallography 55, no. 4 (April 1, 1999): 877–79. http://dx.doi.org/10.1107/s0907444998014735.

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Periplasmic nitrate reductase from the sulfate-reducing bacterium Desulfovibrio desulfuricans ATCC 27774 contains two molybdopterin guanine dinucleotide cofactors and one [4Fe–4S] cluster as prosthetic groups and catalyzes the conversion of nitrate to nitrite. Crystals of the oxidized form of this enzyme were obtained using PEG as precipitant and belong to space group P3121 or P3221, with unit-cell dimensions a = b = 106.3, c = 135.1 Å. There is one monomer of 80 kDa in the asymmetric unit, which corresponds to a Matthews ratio of 2.75 Å3 Da−1. Using cryo-cooling procedures and X-rays from a rotating-anode generator, diffraction was observed to beyond 3.0 Å resolution.

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Krieger, Christoph, Klaus Desch, Jochen Kaminski, and Michael Lupberger. "Operation of an InGrid based X-ray detector at the CAST experiment." EPJ Web of Conferences 174 (2018): 02008. http://dx.doi.org/10.1051/epjconf/201817402008.

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The CERN Axion Solar Telescope (CAST) is searching for axions and other particles which could be candidates for DarkMatter and even Dark Energy. These particles could be produced in the Sun and detected by a conversion into soft X-ray photons inside a strong magnetic field. In order to increase the sensitivity for physics beyond the Standard Model, detectors with a threshold below 1 keV as well as efficient background rejection methods are required to compensate for low energies and weak couplings resulting in very low detection rates. Those criteria are fulfilled by a detector utilizing the combination of a pixelized readout chip with an integrated Micromegas stage. These InGrid (Integrated Grid) devices can be build by photolithographic postprocessing techniques, resulting in a close to perfect match of grid and pixels facilitating the detection of single electrons on the chip surface. The high spatial resolution allows for energy determination by simple electron counting as well as for an event-shape based analysis as background rejection method. Tests at an X-ray generator revealed the energy threshold of an InGrid based X-ray detector to be well below the carbon Kα line at 277 eV. After the successful demonstration of the detectors key features, the detector was mounted at one of CAST’s four detector stations behind an X-ray telescope in 2014. After several months of successful operation without any detector related interruptions, the InGrid based X-ray detector continues data taking at CAST in 2015. During operation at the experiment, background rates in the order of 10−5 keV−1 cm−2 s−1 have been achieved by application of a likelihood based method discriminating the non-photon background originating mostly from cosmic rays. For continued operation in 2016, an upgraded InGrid based detector is to be installed among other improvements including decoupling and sampling of the signal induced on the grid as well as a veto scintillator to further lower the observed background rates and improving sensitivity.

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Cvetic, Jovan. "Tesla’s high voltage and high frequency generators with oscillatory circuits." Serbian Journal of Electrical Engineering 13, no. 3 (2016): 301–33. http://dx.doi.org/10.2298/sjee1603301c.

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The principles that represent the basics of the work of the high voltage and high frequency generator with oscillating circuits will be discussed. Until 1891, Tesla made and used mechanical generators with a large number of extruded poles for the frequencies up to about 20 kHz. The first electric generators based on a new principle of a weakly coupled oscillatory circuits he used for the wireless signal transmission, for the study of the discharges in vacuum tubes, the wireless energy transmission, for the production of the cathode rays, that is x-rays and other experiments. Aiming to transfer the signals and the energy to any point of the surface of the Earth, in the late of 19th century, he had discovered and later patented a new type of high frequency generator called a magnifying transmitter. He used it to examine the propagation of electromagnetic waves over the surface of the Earth in experiments in Colorado Springs in the period 1899-1900. Tesla observed the formation of standing electromagnetic waves on the surface of the Earth by measuring radiated electric field from distant lightning thunderstorm. He got the idea to generate the similar radiation to produce the standing waves. On the one hand, signal transmission, i.e. communication at great distances would be possible and on the other hand, with more powerful and with at least three magnifying transmitters the wireless transmission of energy without conductors at any point of the Earth surface could also be achieved. The discovery of the standing waves on the surface of the Earth and the invention of the magnifying transmitter he claimed his greatest inventions. Less than two years later, at the end of 1901, he designed and started to build a much stronger magnifying transmitter on Long Island near New York City (the Wardenclyffe tower) wishing to become a world telecommunication center. During the tower construction, he elaborated the plans for an even stronger transmitter based on new principles. Due to lack of the funds Tesla was forced to sell or to return the devices and apparatus, he gathered in the Wardenclyffe tower facility, which intended to use to operate the tower. He left the tower in 1907 and since then he was mainly engaged in inventions that were not directly related to the electrical engineering. The unfinished magnifying transmitter on Long Island was demolished in June 1917 by the American government.

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Ritchie, Nicholas W. M. "Using DTSA-II to Simulate and Interpret Energy Dispersive Spectra from Particles." Microscopy and Microanalysis 16, no. 3 (April 20, 2010): 248–58. http://dx.doi.org/10.1017/s1431927610000243.

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AbstractA high quality X-ray spectrum image of a 3.3 μm diameter sphere of K411 glass resting on a copper substrate was collected at 25 keV. The same sample configuration was modeled using the NISTMonte Monte Carlo simulation of electron and X-ray transport as is integrated into the quantitative X-ray microanalysis software package DTSA-II. The distribution of measured and simulated X-ray intensity compare favorably for all the major lines present in the spectra. The simulation is further examined to investigate the influence of angle-of-incidence, sample thickness, and sample diameter on the generated and measured X-ray intensity. The distribution of generated X-rays is seen to deviate significantly from a naive model which assumes that the distribution of generated X-rays is similar to bulk within the volume they share in common. It is demonstrated that the angle at which the electron beam strikes the sample has nonnegligible consequences. It is also demonstrated that within the volume that the bulk and particle share in common that electrons, which have exited and later reentered the particle volume, generate a significant fraction of the X-rays. Any general model of X-ray generation in particles must take into account the lateral spread of the scattered electron beam.

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Fiedorowicz, H., A. Bartnik, Z. Patron, and P. Parys. "Generation of nanosecond soft X-ray pulses as a result of interaction of the Nd: glass laser radiation with gas puff targets." Laser and Particle Beams 12, no. 3 (September 1994): 471–83. http://dx.doi.org/10.1017/s0263034600008338.

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A new method of generation of nanosecond soft X-ray pulses with a photon energy around 1 keV is presented. X-rays are generated in a high-temperature plasma, which is created as a result of the interaction of Nd:glass laser radiation with a gas puff target. The target was obtained by puffing a small amount of gas through the nozzle into the vacuum chamber by means of a pressure electromagnetic valve. The pulses of laser radiation, with pulse duration of 1 ns and energy up to 15 J, generated in the system of a high-power Nd:glass laser were used for the target heating. Spatial, spectral, and temporal measurements of X-ray emission have shown that the high-intensity soft X rays are generated as a result of the interaction of nanosecond pulses of Nd:glass laser radiation with the gas puff target. A high efficiency of X-ray generation is suggested to be related to the effect of condensation of the gas outflowing from the valve nozzle and, in effect, to the interaction of laser radiation with matter in a form of aerosol.

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TERASAWA, M. "HIGH-RESOLUTION PIXE USING BRAGG’S SPECTROMETER." International Journal of PIXE 01, no. 03 (January 1991): 251–58. http://dx.doi.org/10.1142/s0129083591000172.

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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.

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Gauvin, Raynald. "A Universal Equation for the Emission Range of X Rays from Bulk Specimens." Microscopy and Microanalysis 13, no. 5 (September 28, 2007): 354–57. http://dx.doi.org/10.1017/s143192760707081x.

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The derivation of a universal equation to compute the range of emitted X rays is presented for homogeneous bulk materials. This equation is based on two fundamental assumptions: the φ(ρz) curve of X-ray generation is constant and the ratio of the emitted to the generated X-ray range is equal to the ratio of the emitted to the generated X-ray intensity. An excellent agreement is observed with data obtained from Monte Carlo simulations of 200,000 electron trajectories in C, Al, Cu, Ag, Au, and an Fe–B alloy with boron weight fractions equal to 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 0.99, performed with the electron beam energy varied from 1 to 30 keV in 1-keV steps. When the ratio of the generated X-ray range to the photon mean free path is much smaller than one, the emission X-ray range is equal to the generated X-ray range, but when this ratio is much greater than one, the emission X-ray range is constant and is given by the product of the effective photon mean free path multiplied by the sine of the take-off angle.

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Connor Fox, Gavin. "Generation X-ray – A coming of age." Arbor 191, no. 772 (April 30, 2015): a221. http://dx.doi.org/10.3989/arbor.2015.772n2007.

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Lifshin, E., L. A. Peluso, and R. Gauvin. "The Role of Monte Carlo Calculations In Quantitative Analysis." Microscopy and Microanalysis 4, S2 (July 1998): 232–33. http://dx.doi.org/10.1017/s1431927600021280.

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In conventional quantitative electron microprobe analysis, methods like ZAF and φ(ρz), are used to convert x-ray intensity data to chemical composition utilizing equations that describe electron solid interactions, the x-ray generation process, absorption of the generated x-rays and secondary fluorescence effects. These equations capture the overall response of a sample or standard rather than consider the fate of individual electrons over time. For example, f(χ) is simply the ratio of x-rays emitted to the number generated. While for the most part these methods are built on solid physical models, the models were never exact enough to completely match measured data. Consequently, they have been modified by various adjustable parameters to ensure a high level of accuracy for a wide variety of systems and experimental conditions. However, since most of the adjustments were based on data taken at normal incidence, there has always been a question of how to obtain accurate results from tilted samples.

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Yu, Wei, Nikunjkumar Visaveliya, Christophe A. Serra, J. Michael Köhler, Shukai Ding, Michel Bouquey, René Muller, Marc Schmutz, and Isabelle Kraus. "Preparation and Deep Characterization of Composite/Hybrid Multi-Scale and Multi-Domain Polymeric Microparticles." Materials 12, no. 23 (November 27, 2019): 3921. http://dx.doi.org/10.3390/ma12233921.

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Polymeric microparticles were produced following a three-step procedure involving (i) the production of an aqueous nanoemulsion of tri and monofunctional acrylate-based monomers droplets by an elongational-flow microemulsifier, (ii) the production of a nanosuspension upon the continuous-flow UV-initiated miniemulsion polymerization of the above nanoemulsion and (iii) the production of core-shell polymeric microparticles by means of a microfluidic capillaries-based double droplets generator; the core phase was composed of the above nanosuspension admixed with a water-soluble monomer and gold salt, the shell phase comprised a trifunctional monomer, diethylene glycol and a silver salt; both phases were photopolymerized on-the-fly upon droplet formation. Resulting microparticles were extensively analyzed by energy dispersive X-rays spectrometry and scanning electron microscopy to reveal the core-shell morphology, the presence of silver nanoparticles in the shell, organic nanoparticles in the core but failed to reveal the presence of the gold nanoparticles in the core presumably due to their too small size (c.a. 2.5 nm). Nevertheless, the reddish appearance of the as such prepared polymer microparticles emphasized that this three-step procedure allowed the easy elaboration of composite/hybrid multi-scale and multi-domain polymeric microparticles.

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Gao, Ning, and David Rohdeb. "Using a Polycapillary Optic as a Spatial Filter to Improve Micro Xray Analysis in Low-Vacuum and Environmental SEM Systems." Microscopy and Microanalysis 7, S2 (August 2001): 700–701. http://dx.doi.org/10.1017/s1431927600029573.

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An inevitable consequence of the presence of the gas in the sample chamber of a low-vacuum scanning electron microscope (LV-SEM) and environmental SEM (ESEM) is the electron beam broadening due to the scattering in the gas. The electron broadening has a large impact on x-ray analysis because the fluorescent characteristic x rays generated far from the center of the electron probe form a high background, which reduces the detection sensitivity of x-ray analysis and degrades the x-ray image contrast. We report in this paper of using a polycapillary focusing x-ray optic between the sample and the energy-dispersive spectrometer as a spatial filter to filter out unwanted x-rays generated far from the specimen. As a result, the x-ray image contrast and the detection sensitivity of the system were notably improved.A polycapillary focusing optic collects a large solid angle of x rays from an x-ray source of small area at its input focus, guide them through the curved channels by multiple external total reflections, and focus them to the output focus.

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Zakhary, Nardine, and Kingman Strohl. "1243 A Guinness Book Challenge in Upper Airway Stimulation Activation." Sleep 43, Supplement_1 (April 2020): A474. http://dx.doi.org/10.1093/sleep/zsaa056.1237.

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Abstract Introduction Upper airway stimulation is a option for CPAP-intolerant patients. Device activation is typically ~4 weeks after the implant procedure. Report of Case A 61yo male with severe OSA had an upper airway stimulation device placed by ENT. At that time, stimulation produced bilateral tongue protrusion. In the immediate post-operative period, after closure, a hematoma, at the inferior chest incision, was discovered and drained with cauterization of the bleeding vessel. Seven weeks after implant, patient reported to our sleep clinic for activation of the device; and at that time, there was no sensation or activation up to the maximum amplitude of 5mV. The device reported an acceptable respiratory waveform, and triggering on and off sets but without sensory outcomes. Changing of the electrode configuration with advanced settings had no effect. Impedance values were acceptable. Tongue movements were grossly intact. At 2 months, ENT evaluation found mild hypoglossal nerve neuropraxia. To assess for a device related issue, x-rays of the neck and chest were performed and showed proper placement of the device. At 3.5 months, neuropraxia had resolved but device activation was unsuccessful, with no sensory or motor activation to 5mV stimulation. Plans were made for a procedure during which the lead electrode or implantable pulse generator would be assessed or replaced. At 4 months after implantation, in a multidisciplinary appointment with Sleep, ENT and the device representative, with a 3 electrode negative pole and the generator as the + pole, at 2.3mV, the device was activated. At the present time, the patient is exploring higher and lower mV settings and a PSG titration is scheduled. Conclusion This is the longest recorded duration (3.5+ months) of unsuccessful post-operative activation; and it occurred ~2 months after clinical signs of hypoglossal nerve neuropraxia had resolved.

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Honda, Hiroyuki, Shinji Fukao, Kazuyuki Ito, Yang Guan, Yoshikazu Nakanishi, Yuuki Sato, Yoshiaki Ito, and Shinzo Yoshikado. "Evaluation of Compact X-Ray Source Using Multiple LiTaO₃ Single Crystals." Key Engineering Materials 485 (July 2011): 295–98. http://dx.doi.org/10.4028/www.scientific.net/kem.485.295.

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Three and six LiTaO3 single crystals are used to achieve continuous emission of high-intensity X-rays. Furthermore, the interaction between X-rays and the case of the X-ray source is used to generate electrons. X-rays were emitted continuously and fluctuations in the count rate were reduced when three or six crystals were used. Moreover, the X-ray intensity increased and the number of electrons generated by the above-mentioned interaction increased with increasing number of crystals.

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REICH, CH, P. GIBBON, I. USCHMANN, and E. FÖRSTER. "Numerical studies on the properties of femtosecond laser plasma Kα sources." Laser and Particle Beams 19, no. 1 (January 2001): 147–50. http://dx.doi.org/10.1017/s0263034601191238.

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One of the features of ultra high intensity (UHI) short pulse laser–matter interactions is the prospect of creating a cheap, compact source of hard X rays with femtosecond pulse duration. The properties of such Kα sources are studied using analytical and numerical models of hot electron generation and subsequent transport in a range of materials (Reich et al., 2000). First, we find that there is an optimum laser intensity for Kα generation from bulk targets, which scales as Z4.4. Second, we show that efficient hard X-ray pulses with durations below 100 fs can be generated at intensities of ∼1016 W/cm2.

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Chaddha, Mahima, Sneha Kashid, and Snehal Bhosale Prof Radha Deoghare. "Deep Learning for X-ray Image to Text Generation." International Journal of Trend in Scientific Research and Development Volume-3, Issue-3 (April 30, 2019): 1679–82. http://dx.doi.org/10.31142/ijtsrd23168.

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37

Poldi, Eduardo H. T., Carlos A. Escanhoela Jr, Jairo Fonseca Jr, Marcos A. S. Eleotério, Ricardo D. dos Reis, Jonathan C. Lang, Daniel Haskel, and Narcizo M. Souza-Neto. "A versatile X-ray phase retarder for lock-in XMCD measurements." Journal of Synchrotron Radiation 27, no. 5 (August 6, 2020): 1240–46. http://dx.doi.org/10.1107/s1600577520009558.

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X-ray magnetic circular dichroism (XMCD) is a technique commonly used to probe magnetic properties of materials with element and orbital selectivity, which requires the use of circularly polarized (CP) X-rays. It is possible to accomplish XMCD experiments with fixed CP and alternating the magnetic field orientation, but most reliable data are obtained when alternating the magnetization orientation and the polarization between right and left helicities. A versatile strategy has been developed to perform XMCD experiments using a hard X-ray quarter-wave plate, at both polychromatic dispersive and conventional monochromatic optics, in combination with synchronous data acquisition. The switching frequency waveform is fed into a lock-in amplifier to detect and amplify the XMCD signal. The results on a reference sample demonstrate an improvement in data quality and acquisition time. The instrumentation successfully generated 98% of CP X-rays switching the beam helicity at 13 Hz, with the possibility of faster helicity switching once it is installed at the new Brazilian fourth-generation source, SIRIUS.

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Lyman, C. E., and D. W. Ackland. "The standard hole-count test: A progress report." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 720–21. http://dx.doi.org/10.1017/s0424820100087914.

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Analytical electron microscopy (AEM) was well served by the original hole count test that prompted microscope manufacturers to reduce, by an order of magnitude, spurious x-ray generation in the specimen. This spurious x-ray signal is caused by hard x-rays or uncollimated electrons from the illumination system and is typically generated over the entire specimen regardless of where the electron probe is placed for analysis. The original test was performed on an ion-milled thin foil disk specimen of Ag or Mo, but the absolute value of hole count was dependent upon both specimen and operator. To make progress in die reduction of spurious xrays at intermediate voltages (if the problem is present), a hole-count test on a standard specimen that does not require operator judgement would be useful. The ultimate goal would be to reduce spurious x-rays to a level that would not affect any experiment on any specimen.

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Cantor, Robin, and Hideo Naito. "Practical X-ray Spectrometry with Second-Generation Microcalorimeter Detectors." Microscopy Today 20, no. 4 (July 2012): 38–42. http://dx.doi.org/10.1017/s1551929512000429.

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X-ray spectroscopy is a widely used and extremely sensitive analytical technique for qualitative as well as quantitative elemental analysis. Typically, high-energy-resolution X-ray spectrometers are integrated with a high-spatial-resolution scanning electron microscope (SEM) or transmission electron microscope (TEM) for X-ray microanalysis applications. The focused electron beam of the SEM or TEM excites characteristic X rays that are emitted by the sample. The integrated X-ray spectrometer can then be used to identify and quantify the elemental composition of the sample on a sub-micron length scale. This combination of energy resolution and spatial resolution makes X-ray microanalysis of great importance to the semiconductor industry.

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STEIN, J., E. FILL, D. HABS, G. PRETZLER, and K. WITTE. "Hot electron diagnostics using X-rays and Čerenkov radiation." Laser and Particle Beams 22, no. 3 (July 2004): 315–21. http://dx.doi.org/10.1017/s0263034604223163.

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The propagation of laser-generated hot electrons through matter and across narrow vacuum gaps is studied. We use the ATLAS titanium–sapphire laser of Max-Planck-Institut für Quantenoptik to irradiate aluminum and copper foils at intensities of up to 1019W/cm2, generating electrons with temperatures in the megaelectron volt range. After propagating through the target the electrons are detected by means of visible Čerenkov radiation generated in a dielectric or hard X-rays emitted from an X-ray “fluor.” These diagnostics allow the electrons to be characterized with respect to their energy, number, and directionality. We also investigate the propagation of the hot electrons across narrow vacuum gaps, with a width ranging from 500 μm down to 50 μm. The effect of self-generated fields in preventing electrons from crossing the gap is demonstrated. Implications of these experiments with respect to fast ignitor physics, developing optics for fourth-generation light sources and X-ray lasers are indicated.

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Armstrong, John T., and Paul K. Carpenter. "Experimental Evaluation of Absolute X-RAY Intensities at Low to Moderate Beam Energies." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 12–13. http://dx.doi.org/10.1017/s0424820100133655.

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Knowledge of the absolute electron-induced production of the characteristic x-rays for different lines and elements is required for proper evaluation of the characteristic fluorescence correction or for development of “standardless” x-ray quantitative analysis correction procedures. Determination of absolute generated x-ray intensities in thick specimens or even relative generated x-ray intensities for lines of different elements in thick specimens is quite difficult as demonstrated by the lack of agreement of the published attempts to determine absolute generated x-ray intensity yields. The amount of absorption of the generated x-ray intensity in the sample and the amount of x-ray production from secondary fluorescence by other characteristic lines or by the continuum must be calculated. Moreover, the detector efficiency for measuring the different lines must be known. Most investigations of absolute generated x-ray intensities suggest that there is a functional relationship between the generated intensity and the overvoltage (U = Eo/Ec) at which the measurement is made.

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Kusminarto and Ramacos Fadela. "An X-Ray Detector Using a Fluorescent Material ZnS:Ag Attached on a Phototransistor in Darlington Configuration." Applied Mechanics and Materials 771 (July 2015): 21–24. http://dx.doi.org/10.4028/www.scientific.net/amm.771.21.

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X-rays have been widely used in medical imaging system. CT Scan is one of the important diagnostic equipments in medical field that uses X-rays as a probe. In the latest CT-Scan generation an array of X-ray detector in a gantry is employed. Solid state detector and gas filled detector are currently used. These type of detector have relatively large in physical size. This influenses the size of the machine as well as its performance. In order to obtain an X-ray detector in a small size a phototransistor was exploited. The phototransistor was attached on a fluoroscent screen and arranged in Darlington configuration. The phototransistor in Darlington configuration was calibrated using visible light. The results showed that there was a linear correlation between the phototransistor output (mV) and the light intensity impinging on the phototransistor surface. A fluoroscent material (ZnS:Ag) then attached on the phototransistor surface. They work as an X-ray detector and calibrated using an X-ray beam generated from an X-ray machine. The results also confirmed that there was a linear correlation between the detector output (mV) and the X-ray intensity stricking the detector surface. The active area of the detector was explored by scanning the surface of the detector in vertical as well as in horizontal directions. The effective diameter of the active area of the detector was found to be 2.2 mm.

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Takahashi, Kenji, Satoru Monzen, and Ikuo Kashiwakura. "Tie-2-Expression Controls the Radio-Sensitivity of Hematopoietic Stem/Progenitor Cells." Blood 110, no. 11 (November 16, 2007): 4034. http://dx.doi.org/10.1182/blood.v110.11.4034.4034.

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Abstract Tyrosine kinase with immunoglobulin and epidermal growth factor homology domains 2 (Tie-2) and its ligand, angiopoietin-1 (Ang-1) play an important role in the remodeling and maturation the vessels. However, Tie-2 expressed in hematopoietic stem cells has been reported to interact with Ang-1 on stromal osteoblasts in the bone marrow niche. This interaction leads to tight adhesion of hematopoietic stem cells to stromal cells, resulting in the maintenance of long-term repopulating activity of hematopoietic stem cells. Although the high radio-sensitivity of hematopoietic stem/progenitor cells is a serious cause of radiation damage in accidentally irradiated victims, the relationship of Tie-2/Ang-1-signals relate to radio-sensitivity is unclear. In addition, a diagnosis of specific radio-sensitivity in patients with malignant diseases allows radio- and/or chemo-therapy to be performed more effectively. Therefore, the radio-protection activity and the possible association of to radio-sensitivity in hematopoietic stem/progenitor of Tie-2/Ang-1 signaling was evaluated. This study was approved by the Committee of Medical Ethics of Hirosaki University School of Medicine. CD34+ hematopoietic stem/progenitor cells were isolated using a magnet sorting kit from human placental and umbilical cord blood units (n = 33) at the end of full-term deliveries after obtaining informed consent from the mothers. Each purified CD34+ fraction individually (81.3 ± 13.7%) was analyzed for the expression of Tie-2 using a flow cytometer. The range of Tie-2-expression was 1.6 ∼ 12.4% (mean = 5.13%). Based on the Tie-2-positive rate, all 33 fractions were classified into CD34+/Tie-2low fraction (Tie-2 positive rate; < 5%, n = 17) or CD34+/Tie-2high fraction (Tie-2 positive rate; ≥ 5%, n = 16). The CD34+ cells were exposed to X-rays at 2 Gy by an X-rays generator (150 kVp, 20 mA, 0.8 ∼ 0.95 Gy/min). The radio-sensitivity of the hematopoietic stem/progenitor cells of each specimen was measured using clonogenic assays. Specifically, the BFU-E, CFU-GM and CFU-GEMM of each sample were assessed in triplicate using a 14-day culture assay in a methylcellulose medium with 5 growth factors (EPO; 4 U/ml, SCF and IL-3; 100 ng/ml, G-CSF and GM-CSF; 10 ng/ml). In addition, CFU-Meg was assessed in triplicate using a 14-day plasma clot technique with 2 growth factors (TPO; 50 ng/ml, SCF; 100 ng/ml). Unexpectedly, the total CFC number decreased with the expression of Tie-2 in CD34+ cells and the total CFC number in CD34+/Tie-2high fractions was lower than that of CD34+/Tie-2low fractions. Moreover, the survival of total CFC at 2 Gy and Tie-2-expression were positively correlated in the CD34+ cells and the total CFC number in CD34+/Tie-2high fractions was more resistant to X-rays than that of CD34+/Tie-2low fractions. Furthermore, to clarify the interaction radio-sensitivity and Tie-2-expression, the effect of Ang-1 on the radio-protective activity in X-irradiated CD34+ cells was examined. However, no protective effect was observed. Although previous reports have showed that CD34+/Tie-2+ cells were more primitive than CD34+/Tie-2− cells, these results suggested that Tie-2-expression appeared to enhance the radio-resistant ability of CD34+ cells and that it was a marker for a radio-sensitivity. Since the direct activation by Ang-1 was not associated with the survival of X-irradiated CD34+ cells, another signaling mechanism may thus be involved in the radio-resistance activity of Tie-2.

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Wang, Wei-Min, Zheng-Ming Sheng, Paul Gibbon, Li-Ming Chen, Yu-Tong Li, and Jie Zhang. "Collimated ultrabright gamma rays from electron wiggling along a petawatt laser-irradiated wire in the QED regime." Proceedings of the National Academy of Sciences 115, no. 40 (September 17, 2018): 9911–16. http://dx.doi.org/10.1073/pnas.1809649115.

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Even though high-quality X- and gamma rays with photon energy below mega-electron volt (MeV) are available from large-scale X-ray free electron lasers and synchrotron radiation facilities, it remains a great challenge to generate bright gamma rays over 10 MeV. Recently, gamma rays with energies up to the MeV level were observed in Compton scattering experiments based on laser wakefield accelerators, but the yield efficiency was as low as10−6, owing to low charge of the electron beam. Here, we propose a scheme to efficiently generate gamma rays of hundreds of MeV from submicrometer wires irradiated by petawatt lasers, where electron accelerating and wiggling are achieved simultaneously. The wiggling is caused by the quasistatic electric and magnetic fields induced around the wire surface, and these are so high that even quantum electrodynamics (QED) effects become significant for gamma-ray generation, although the driving lasers are only at the petawatt level. Our full 3D simulations show that directional, ultrabright gamma rays are generated, containing1012photons between 5 and 500 MeV within a 10-fs duration. The brilliance, up to1027photonss−1 mrad−2 mm−2per 0.1% bandwidth at an average photon energy of 20 MeV, is second only to X-ray free electron lasers, while the photon energy is 3 orders of magnitude higher than the latter. In addition, the gamma ray yield efficiency approaches 10%—that is, 5 orders of magnitude higher than the Compton scattering based on laser wakefield accelerators. Such high-energy, ultrabright, femtosecond-duration gamma rays may find applications in nuclear photonics, radiotherapy, and laboratory astrophysics.

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Petit, V., D. H. Cohen, Y. Nazé, M. Gagné, R. H. D. Townsend, M. A. Leutenegger, A. ud-Doula, S. P. Owocki, and G. A. Wade. "X-rays from magnetic massive OB stars." Proceedings of the International Astronomical Union 9, S302 (August 2013): 330–33. http://dx.doi.org/10.1017/s1743921314002427.

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AbstractThe magnetic activity of solar-type and low-mass stars is a well known source of coronal X-ray emission. At the other end of the main sequence, X-rays emission is instead associated with the powerful, radiatively driven winds of massive stars. Indeed, the intrinsically unstable line-driving mechanism of OB star winds gives rise to shock-heated, soft emission (~0.5 keV) distributed throughout the wind. Recently, the latest generation of spectropolarimetric instrumentation has uncovered a population of massive OB-stars hosting strong, organized magnetic fields. The magnetic characteristics of these stars are similar to the apparently fossil magnetic fields of the chemically peculiar ApBp stars. Magnetic channeling of these OB stars' strong winds leads to the formation of large-scale shock-heated magnetospheres, which can modify UV resonance lines, create complex distributions of cooled Halpha emitting material, and radiate hard (~2-5 keV) X-rays. This presentation summarizes our coordinated observational and modelling efforts to characterize the manifestation of these magnetospheres in the X-ray domain, providing an important contrast between the emission originating in shocks associated with the large-scale fossil fields of massive stars, and the X-rays associated with the activity of complex, dynamo-generated fields in lower-mass stars.

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Brownridge, James D. "Pyroelectric X-ray generator." Nature 358, no. 6384 (July 1992): 287–88. http://dx.doi.org/10.1038/358287b0.

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Poulsen, Henning F., Dorte Juul Jensen, and Gavin B. M. Vaughan. "Three-Dimensional X-Ray Diffraction Microscopy Using High-Energy X-Rays." MRS Bulletin 29, no. 3 (March 2004): 166–69. http://dx.doi.org/10.1557/mrs2004.54.

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AbstractThree-dimensional x-ray diffraction (3DXRD) microscopy is a tool for fast and nondestructive characterization of the individual grains, subgrains, and domains inside bulk materials. The method is based on diffraction with very penetrating hard x-rays (E ≥ 50 keV), enabling 3D studies of millimeter-to-centimeter-thick specimens.The position, volume, orientation, and elastic and plastic strain can be derived for hundreds of grains simultaneously. Furthermore, by applying novel reconstruction methods, 3D maps of the grain boundaries can be generated. The 3DXRD microscope in use at the European Synchrotron Radiation Facility in Grenoble, France, has a spatial resolution of ∼5 μm and can detect grains as small as 150 nm. The technique enables, for the first time, dynamic studies of the individual grains within polycrystalline materials. In this article, some fundamental materials science applications of 3DXRD are reviewed: studies of nucleation and growth kinetics during recrystallization, recovery, and phase transformations, as well as studies of polycrystal deformation.

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Shao, Tao, Victor F. Tarasenko, Cheng Zhang, Evgeni KH Baksht, Ping Yan, and Yuliya V. Shut'Ko. "Repetitive nanosecond-pulse discharge in a highly nonuniform electric field in atmospheric air: X-ray emission and runaway electron generation." Laser and Particle Beams 30, no. 3 (May 25, 2012): 369–78. http://dx.doi.org/10.1017/s0263034612000201.

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AbstractRepetitive nanosecond-pulse discharge with a highly inhomogeneous electric field was investigated in air at atmospheric pressure. Three repetitive nanosecond generators were used, and the rise times of the voltage pulses were 15, 1, and 0.2 ns, respectively. Under different experimental conditions, X-rays and runaway electron beams were directly measured using various setups. The variables affecting X-rays and runaway electrons, including gap distance, pulse repetition frequency, anode geometry, and material, were investigated. It was shown that it was significantly easier to record the X-rays than the runaway electrons in the repetitive nanosecond-pulse discharge. It was confirmed that a volume diffuse discharge was attributed to the generation of runaway electrons and the corresponding X-rays.

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Johnson, Allan S., Timur Avni, Esben W. Larsen, Dane R. Austin, and Jon P. Marangos. "Attosecond soft X-ray high harmonic generation." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2145 (April 2019): 20170468. http://dx.doi.org/10.1098/rsta.2017.0468.

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High harmonic generation (HHG) of an intense laser pulse is a highly nonlinear optical phenomenon that provides the only proven source of tabletop attosecond pulses, and it is the key technology in attosecond science. Recent developments in high-intensity infrared lasers have extended HHG beyond its traditional domain of the XUV spectral range (10–150 eV) into the soft X-ray regime (150 eV to 3 keV), allowing the compactness, stability and sub-femtosecond duration of HHG to be combined with the atomic site specificity and electronic/structural sensitivity of X-ray spectroscopy. HHG in the soft X-ray spectral region has significant differences from HHG in the XUV, which necessitate new approaches to generating and characterizing attosecond pulses. Here, we examine the challenges and opportunities of soft X-ray HHG, and we use simulations to examine the optimal generating conditions for the development of high-flux, attosecond-duration pulses in the soft X-ray spectral range. This article is part of the theme issue ‘Measurement of ultrafast electronic and structural dynamics with X-rays’.

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Marangos, J. P. "The measurement of ultrafast electronic and structural dynamics with X-rays." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, no. 2145 (April 2019): 20170481. http://dx.doi.org/10.1098/rsta.2017.0481.

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In this theme issue, leading researchers discuss recent work on the measurement of ultrafast electronic and structural dynamics in matter using a new generation of short duration X-ray photon sources. These photon sources, based upon high harmonic generation from lasers and X-ray free-electron lasers, look set to have a high impact on ultrafast science. This article is part of the theme issue ‘Measurement of ultrafast electronic and structural dynamics with X-rays’.

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Journal articles on the topic 'X-rays generator'

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