scholarly journals Compton Sources of Electromagnetic Radiation

2010 ◽  
Vol 03 (01) ◽  
pp. 147-163 ◽  
Author(s):  
Geoffrey A. Krafft ◽  
Gerd Priebe
Keyword(s):  
Electron Beam ◽  
Electromagnetic Radiation ◽  
Laser Light ◽  
Review Article ◽  
X Ray ◽  
Large Numbers ◽  
Radiation Sources ◽  
The World ◽  
Beam Motion ◽  
Polarized Photons

When a relativistic electron beam interacts with a high-field laser beam, intense and highly collimated electromagnetic radiation will be generated through Compton scattering. Through relativistic upshifting and the relativistic Doppler effect, highly energetic polarized photons are radiated along the electron beam motion when the electrons interact with the laser light. For example, X-ray radiation can be obtained when optical lasers are scattered from electrons of tens-of-MeV beam energy. Because of the desirable properties of the radiation produced, many groups around the world have been designing, building, and utilizing Compton sources for a wide variety of purposes. In this review article, we discuss the generation and properties of the scattered radiation, the types of Compton source devices that have been constructed to date, and the prospects of radiation sources of this general type. Due to the possibilities of producing hard electromagnetic radiation in a device that is small compared to the alternative storage ring sources, it is foreseen that large numbers of such sources may be constructed in the future.

scholarly journals Hard X-ray nanofocusing at low-emittance synchrotron radiation sources

2014 ◽  
Vol 21 (5) ◽  
pp. 996-1005 ◽  
Author(s):  
Christian G. Schroer ◽  
Gerald Falkenberg
Keyword(s):  
Electron Beam ◽  
Synchrotron Radiation ◽  
Storage Ring ◽  
Source Parameters ◽  
Gaussian Model ◽  
Scanning Microscopy ◽  
X Ray ◽  
Radiation Sources ◽  
Central Cone ◽  
Low Emittance

X-ray scanning microscopy relies on intensive nanobeams generated by imaging a highly brilliant synchrotron radiation source onto the sample with a nanofocusing X-ray optic. Here, using a Gaussian model for the central cone of an undulator source, the nanobeam generated by refractive X-ray lenses is modeled in terms of size, flux and coherence. The beam properties are expressed in terms of the emittances of the storage ring and the lateral sizes of the electron beam. Optimal source parameters are calculated to obtain efficient and diffraction-limited nanofocusing. With decreasing emittance, the usable fraction of the beam for diffraction-limited nanofocusing experiments can be increased by more than two orders of magnitude compared with modern storage ring sources. For a diffraction-limited storage ring, nearly the whole beam can be focused, making these sources highly attractive for X-ray scanning microscopy.

scholarly journals Coherent backscattering in the soft X-ray region

1990 ◽  
Vol 8 (3) ◽  
pp. 383-398 ◽  
Author(s):  
A. Luccio ◽  
G. Matone ◽  
L. Miceli ◽  
G. Giordano
Keyword(s):  
Electron Beam ◽  
Laser Radiation ◽  
Relativistic Electron Beam ◽  
Laser Light ◽  
Practical Implementation ◽  
X Rays ◽  
Laser Photon ◽  
X Ray ◽  
Degree Of Coherence ◽  
High Degree

Coherent X rays can be produced by Compton scattering of laser light on a relativistic electron beam, whose current is periodically modulated by the same laser radiation in a suitable miniundulator. If electron and laser photon energy are properly matched, the modulated electron beam acts as a moving diffraction grating and the X rays show a high degree of coherence. A practical implementation of this scheme is shown.

scholarly journals Quantitative investigation of linear arbitrary polarization in an APPLE-II undulator

2018 ◽  
Vol 25 (2) ◽  
pp. 378-384
Author(s):  
Matthew Hand ◽  
Hongchang Wang ◽  
Francesco Maccherozzi ◽  
Marco Apollonio ◽  
Jingtao Zhu ◽  
...  
Keyword(s):  
Electron Beam ◽  
Synchrotron Radiation ◽  
Light Source ◽  
Polarization State ◽  
Measured Data ◽  
Beam Polarization ◽  
Quantitative Investigation ◽  
X Ray ◽  
The World

Insertion devices are utilized at synchrotron radiation facilities around the world for their capability to provide a high-brilliance X-ray beam. APPLE-II type undulators are especially important for their capacity to switch between a variety of photon beam polarization states. A high-precision soft X-ray polarimeter has been used to investigate the polarization calibration of an APPLE-II undulator (period length λu= 64 mm) installed on beamline I06 at Diamond Light Source. Systematic measurement of the beam polarization state at a range of linear arbitrary angles has been compared with the expected result for a given set of undulator gap and row phase parameters calculated from theory. Determination of the corresponding Stokes–Poincaré parameters from the measured data reveals a discrepancy between the two. The limited number of energy/polarization combinations included in the undulator calibration tables necessitates the use of interpolated values for the missing points which is expected to contribute to the discrepancy. However, by modifying the orbit of the electron beam through the undulator by at least 160 µm it has been found that for certain linear polarizations the discrepancies can be corrected. Overall, it is suggested that complete correction of the Stokes–Poincaré parameters for all linear angles would require alteration of both these aspects.

scholarly journals COVID-19 Vaccines, What do we know so Far? A Narrative Review

2021 ◽  
Vol 04 (05) ◽  
Author(s):  
Cima Hamieh, MD ◽  
Keyword(s):  
Side Effects ◽  
Mortality Rate ◽  
Mechanism Of Action ◽  
Review Article ◽  
Conspiracy Theories ◽  
Safety And Efficacy ◽  
Large Numbers ◽  
The World ◽  
And Control ◽  
New Vaccines

For more than a year, the world was paralyzed by the COVID-19 pandemic. It wasn’t until the last few months that hope to a return of a quasi-normal way of living was starting to materialize. The era of the COVID-19 vaccines begun, and with it all sorts of concerns and complaints about their safety and efficacy. Large numbers of people believed the conspiracy theories about the new vaccines thus becoming reluctant and sometimes refused to take the new vaccines. Others justified their concern with the relatively short trial periods compared to previous vaccines that used to take years before adoption. Multiple vaccines emerged around the same time, and thus the fight to conquer the market began. Pfizer-BioNTech, Vaxzervria, Moderna, Sputnik, Coronavac, Janssen, all were rapidly distributed to countries around the globe, in order to reduce the mortality rate and control the pandemic. To make things worse, new viral mutations started being detected and thus shed more doubt on the efficacy of these vaccines. This review article summarizes the literature of these vaccines’ pathophysiology, mechanism of action, dosing and schedule, safety profile and lastly the documented side effects of each vaccine. In conclusion, there is no certainty whether these vaccines will prevent infection and more importantly protect against forward transmission. It is sure that the immunity persists for several months, but the exact duration for every vaccine is yet to be determined. For the time being, safety precautions must still be continued; wearing masks, social distancing and avoiding crowded places must be applied.

Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

Microanalysis of precipitates in a ferritic steel

1978 ◽  
Vol 36 (1) ◽  
pp. 618-619
Author(s):  
J.M. Titchmarsh
Keyword(s):  
Ferritic Steel ◽  
Particle Identification ◽  
Energy Dispersive ◽  
Objective Lens ◽  
Ferritic Steels ◽  
Replica Technique ◽  
X Ray ◽  
Large Numbers ◽  
Scanning Transmission ◽  
Made In

The advances in recent years in the microanalytical capabilities of conventional TEM's fitted with probe forming lenses allow much more detailed investigations to be made of the microstructures of complex alloys, such as ferritic steels, than have been possible previously. In particular, the identification of individual precipitate particles with dimensions of a few tens of nanometers in alloys containing high densities of several chemically and crystallographically different precipitate types is feasible. The aim of the investigation described in this paper was to establish a method which allowed individual particle identification to be made in a few seconds so that large numbers of particles could be examined in a few hours.A Philips EM400 microscope, fitted with the scanning transmission (STEM) objective lens pole-pieces and an EDAX energy dispersive X-ray analyser, was used at 120 kV with a thermal W hairpin filament. The precipitates examined were extracted using a standard C replica technique from specimens of a 2¼Cr-lMo ferritic steel in a quenched and tempered condition.

X-ray micro tomography in the scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 106-107 ◽  
Author(s):  
W. Brünger
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Target Surface ◽  
The Body ◽  
X Rays ◽  
Cross Sectional ◽  
X Ray ◽  
Micro Tomography ◽  
Scanning Electron

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

Searching for the causes why some of the paintings by Mihaly Munkacsy are darkening

1990 ◽  
Vol 48 (2) ◽  
pp. 204-205
Author(s):  
Imre Pozsgai ◽  
Klara Erdöhalmi-Torok
Keyword(s):  
Electron Beam ◽  
Cross Section ◽  
Polyester Resin ◽  
National Gallery ◽  
X Ray ◽  
Art Historians ◽  
Made In ◽  
Grinding And Polishing

The paintings by the great Hungarian master Mihaly Munkacsy (1844-1900) made in an 8-9 years period of his activity are deteriorating. The most conspicuous sign of the deterioration is an intensive darkening. We have made an attempt by electron beam microanalysis to clarify the causes of the darkening. The importance of a study like this is increased by the fact that a similar darkening can be observed on the paintings by Munkacsy’s contemporaries e.g Courbet and Makart. A thick brown mass the so called bitumen used by Munkacsy for grounding and also as a paint is believed by the art historians to cause the darkening.For this study, paint specimens were taken from the following paintings: “Studio”, “Farewell” and the “Portrait of the Master’s Wife”, all of them are the property of the Hungarian National Gallery. The paint samples were embedded in a polyester resin “Poly-Pol PS-230” and after grinding and polishing their cross section was used for x-ray mapping.

Estimation of the noise in TEM image recorded on “imaging plate”

1987 ◽  
Vol 45 ◽  
pp. 748-749
Author(s):  
T. Oikawa ◽  
N. Mori ◽  
T. Katoh ◽  
Y. Harada ◽  
J. Miyahara ◽  
...  
Keyword(s):  
Low Dose ◽  
Quantum Noise ◽  
Laser Light ◽  
Imaging Plate ◽  
Total System ◽  
Electron Dose ◽  
X Ray ◽  
Image Recording ◽  
Recording Material ◽  
Highly Sensitive

The “Imaging Plate”(IP) is a highly sensitive image recording plate for X-ray radiography. It has been ascertained that the IP has superior properties and high practicability as an image recording material in a TEM. The sensitivity, one of the properties, is about 3 orders higher than that of conventional photo film. The IP is expected to be applied to low dose techniques. In this paper, an estimation of the quantum noise on the TEM image which appears in case of low electron dose on the IP is reported.In this experiment, the JEM-2000FX TEM and an IP having the same size as photo film were used.Figure 1 shows the schematic diagram of the total system including the TEM used in this experiment. In the reader, He-Ne laser light is scanned across the IP, then blue light is emitted from the IP.

Sign in / Sign up

Export Citation Format

Share Document