Synchrotron radiation

About: Synchrotron radiation is a research topic. Over the lifetime, 14639 publications have been published within this topic receiving 244775 citations. The topic is also known as: magnetobremsstrahlung radiation & Synchrotron Radiation.

Construction of insertion devices for elliptically polarized synchrotron radiation

Abstract: Two new insertion devices for the generation of elliptically polarized synchrotron radiation have been constructed to be installed in two electron storage rings, the Accumulation Ring for the TRISTAN project and the Photon Factory ring at KEK, National Laboratory for High Energy Physics. These new light sources are designed to produce (1) intense radiation with a degree of circular polarization (Pc) between 0.5 and 0.9 in hard x‐ray region, and (2) quasimonochromatic radiation with Pc>0.7 in vacuum ultraviolet region.

In situ 3D quantification of the evolution of creep cavity size, shape, and spatial orientation using synchrotron X-ray tomography

Abstract: Creep lifetime of metallic materials is of high significance for the efficiency and safety, e.g. of electricity-generating power plants and in particular steam and gas turbines. Synchrotron radiation microtomography provides new possibilities for a non-destructive determination of creep damage evolution in the bulk of samples. Cavity volume, shape and orientation evolution are determined here using synchrotron radiation 3D tomograms obtained in situ during creep experiments. The results of the experiments enable a quantitative description of the time dependence of cavity morphology and size distributions.

Laboratory von Hámos X-ray spectroscopy for routine sample characterization.

Abstract: High energy resolution, hard X-ray spectroscopies are powerful element selective probes of the electronic and local structure of matter, with diverse applications in chemistry, physics, biology, and materials science. The routine application of these techniques is hindered by the complicated and slow access to synchrotron radiation facilities. Here we propose a new, economic, easily operated laboratory high resolution von Hamos type X-ray spectrometer, which offers rapid transmission experiments for X-ray absorption and is also capable of recording X-ray emission spectra. The use of a cylindrical analyzer crystal and a position sensitive detector enabled us to build a robust, flexible setup with low operational costs, while delivering synchrotron grade signal to noise measurements in reasonable acquisition times. We demonstrate the proof of principle and give examples for both measurement types. Finally, tracking of a several day long chemical transformation, a case better suited for laboratory than synchrotron investigation, is also presented.

The magnetic field in the X-ray corona of Cygnus X-1

Abstract: The different electron distributions in the hard and soft spectral states (HS and SS) of BH binaries could be caused by kinetic processes and changing because of varying physical conditions in the corona. In presence of a magnetic field in the corona, the electron distribution can appear thermal, even when acceleration mechanisms would produce non thermal distributions. This is due to fast and efficient thermalization through synchrotron self-absorption. We have analyzed data from 6 years of observations of Cygnus X-1 with the INTEGRAL observatory and produced 12 high-quality, stacked broad-band hard X-ray spectra representative of the whole range of spectral shapes observed. We then fit these spectra with hybrid thermal/non-thermal Comptonization models and study the evolution of the physical parameters of the accretion flow across the spectral transition. In particular, we use the BELM model to constrain the magnetic field in the corona through its effects on the coronal emission. Indeed, the hot electrons of the X-ray corona produce soft (optical-UV) synchrotron radiation which is then Comptonized and may affect the temperature of the electrons through Compton cooling. We find that in the SS, the emission is dominated by Comptonization of the disc photons and the magnetic field is at most of the order of 1E+06 G. In the hard states, the data are consistent with a pure synchrotron self-Compton model. If the non-thermal excess observed above a few hundred keV in the HS is produced in the same region as the bulk of the thermal Comptonization, we obtain an upper limit on the coronal magnetic field of about 1E+05 G. If, on the other hand, the non-thermal excess is produced in a different location, the constraints on the magnetic field in the HS are somewhat relaxed and the upper limit rises to 1E+07 G. We discuss these constraints in the context of current accretion flow models.

Effects of nonuniform structure on the derived physical parameters of compact synchrotron sources

Abstract: The time-independent theory of a compact incoherent synchrotron radio source which contains gradients in magnetic field and in relativistic electron distribution is developed and discussed. Analytic expressions for the frequency spectrum are obtained, and we demonstrate the dependence of the spectral index below the synchrotron self-absorption turnover frequency on the gradients in the source and on the source geometry. We show that at high frequencies the existence of a gradient in the magnetic field causes a gradual bend (a steepening) in the spectrum owing to a decrease in effective source radius with increasing frequency. The theoretical interferometric fringe visibility function is computed for a nonuniform source, and it is shown that the characteristic Gaussian angular size derived from this function increases with decreasing frequency below the spectral turnover.We discuss how the important physical parameters of a nonuniform source can be directly derived from observable quantities. The results indicate that the existence of steep gradients in the magnetic field strength and/or the distribution of relativistic electrons can alleviate somewhat the energetic and inverse Compton difficulties of some compact sources, while the presence of moderate gradients only aggravates these problems relative to the homogeneous model.The theory of nonuniform components is applied tomore » the compact radio sources 1633+38 and OQ 172. We find that the radio spectrum of these objects can be interpreted as arising in simple nonuniform sources as opposed to the multiple source models that are necessary when homogeneous components are used. However, the inverse Compton optical and X-ray fluxes in the case of 1633+38 and the predicted minimum angular size in the case of OQ 172 are similar to those obtained via the uniform models.« less