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.

Investigation of artefact sources in synchrotron microtomography via virtual X-ray imaging

Abstract: Qualitative and quantitative use of volumes reconstructed by computed tomography (CT) can be compromised due to artefacts which corrupt the data. This article illustrates a method based on virtual X-ray imaging to investigate sources of artefacts which occur in microtomography using synchrotron radiation. In this phenomenological study, different computer simulation methods based on physical X-ray properties, eventually coupled with experimental data, are used in order to compare artefacts obtained theoretically to those present in a volume acquired experimentally, or to predict them for a particular experimental setup. The article begins with the presentation of a synchrotron microtomographic slice of a reinforced fibre composite acquired at the European Synchrotron Radiation Facility (ESRF) containing streak artefacts. This experimental context is used as the motive throughout the paper to illustrate the investigation of some artefact sources. First, the contribution of direct radiation is compared to the contribution of secondary radiations. Then, the effect of some methodological aspects are detailed, including under-sampling, sample and camera misalignment, sample extending outside of the field of view and photonic noise. The effect of harmonic components present in the experimental spectrum are also simulated. Afterwards, detector properties, such as its impulse response or defective pixels, are taken into account. Finally, the importance of phase contrast effects is evaluated. In the last section, this investigation is discussed by putting emphasis on the experimental context which is used throughout this paper.

Spin-aligned momentum distributions of transition-metal ferromagnets studied with circularly polarized synchrotron radiation.

Abstract: The momentum distributions of the unpaired spin electrons in Fe, Co, and Ni have been measured using circularly polarized x rays produced from an x-ray phase plate developed at the Cornell High Energy Synchrotron Source Estimates of the negative polarization of the $s\ensuremath{-}p$ components of the conduction electrons have been made The spin-dependent transition-metal momentum profiles are compared to theoretical calculations Preliminary results from gadolinium are also presented

The definition of electromagnetic radiation

Abstract: Momentum and energy of electromagnetic radiation emitted from a charge are Lorentz-covariantly defined The non-local measurement of a Lorentz inlariant, the rate of radiation energy emission is proposed as a necessary and sufficient criterion for the emission of radiation at a gilen time This measurement is a field measurement which can be performed atany distance from the charge and need not be made in the wale zone It can be regarded as an operational definition of radiation in terms of rate of energy emission These results permit a simple derilation of the equation of motion of a charged particle which aloids the self-energy difficulties A question concerning the principle of equilalence and radiation in uniformly accelerated motion is answered

Double excitation in the K absorption spectrum of neon

Abstract: The high resolution spectrum of gaseous neon in the 1s region was obtained by using synchrotron radiation. In addition to previously observed single-electron excitation lines, the authors observed two new sharp lines of comparable intensities in the continuum at 35.1 and 38.1 eV above the 1s to 3p resonance line. On the basis of the known Ne 1s XPS shake-up lines the authors attribute them to transitions to 1P0 levels of the 1s2s22P53p2 final-state configuration.

Microfabrication using synchrotron radiation

Abstract: The realization of precision deep microstructures requires high-energy, intense parallel beams of x-rays from synchrotron radiation sources and novel process technology. Deep x-ray lithography with synchrotron radiation is basically a shadow printing process in which a two-dimensional pattern is accurately transferred from a mask into a resist material by chemical changes induced by the radiation. Subsequent electroforming and moulding processes are used to manufacture microstructures from metals, plastics and ceramics. This process, known as LIGA (LIthographie, Galvanoformung, and Abformung), first developed in Germany, is based on a combination of lithography, electroforming and replication processes. The development of the LIGA process for the fabrication of a wide range of precision microstructures has been stimulated by the increasing use of synchrotron radiation sources for lithography. Applications for microstructures exist in many sectors of industry. These include chemical and process engineering, biomedical instrumentation, automotive and aerospace technology, environmental monitoring and information technology. Emphasis is placed on three main areas, micromechanics, micro-optics and microfluidics, which are emerging with the widest range of industrial applications. This paper reviews the progress being made in microfabrication technology using x-ray beam lithography and the LIGA process. It includes a description of synchrotron radiation, storage ring sources, the fabrication processes, applications and potential markets. Reference is also made to European networks and R&D activity worldwide.