Topic
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.
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TL;DR: DESIRS as discussed by the authors is a new undulator-based VUV beamline optimized for gas-phase studies of molecular and electronic structures, reactivity and polarization-dependent photodynamics on model or actual systems encountered in the universe, atmosphere and biosphere.
Abstract: DESIRS is a new undulator-based VUV beamline on the 2.75 GeV storage ring SOLEIL (France) optimized for gas-phase studies of molecular and electronic structures, reactivity and polarization-dependent photodynamics on model or actual systems encountered in the universe, atmosphere and biosphere. It is equipped with two dedicated endstations: a VUV Fourier-transform spectrometer (FTS) for ultra-high-resolution absorption spectroscopy (resolving power up to 106) and an electron/ion imaging coincidence spectrometer. The photon characteristics necessary to fulfill its scientific mission are: high flux in the 5–40 eV range, high spectral purity, high resolution, and variable and well calibrated polarizations. The photon source is a 10 m-long pure electromagnetic variable-polarization undulator producing light from the very near UV up to 40 eV on the fundamental emission with tailored elliptical polarization allowing fully calibrated quasi-perfect horizontal, vertical and circular polarizations, as measured with an in situ VUV polarimeter with absolute polarization rates close to unity, to be obtained at the sample location. The optical design includes a beam waist allowing the implementation of a gas filter to suppress the undulator high harmonics. This harmonic-free radiation can be steered toward the FTS for absorption experiments, or go through a highly efficient pre-focusing optical system, based on a toroidal mirror and a reflective corrector plate similar to a Schmidt plate. The synchrotron radiation then enters a 6.65 m Eagle off-plane normal-incidence monochromator equipped with four gratings with different groove densities, from 200 to 4300 lines mm−1, allowing the flux-to-resolution trade-off to be smoothly adjusted. The measured ultimate instrumental resolving powers are 124000 (174 µeV) around 21 eV and 250000 (54 µeV) around 13 eV, while the typical measured flux is in the 1010–1011 photons s−1 range in a 1/50000 bandwidth, and 1012–1013 photons s−1 in a 1/1000 bandwidth, which is very satisfactory although slightly below optical simulations. All of these features make DESIRS a state-of-the-art VUV beamline for spectroscopy and dichroism open to a broad scientific community.
282 citations
01 Jan 1983
TL;DR: The radio spectrum of Jupiter has been observed over 24 octaves of the radio spectrum, from about 0.01 MHz to 300,000 MHz, and three distinct types of radiation are responsible for this radio spectrum: thermal emission from the atmosphere accounts for virtually all the radiation at the high frequency end as mentioned in this paper.
Abstract: Jupiter has now been observed over 24 octaves of the radio spectrum, from about 0.01 MHz to 300,000 MHz. Its radio emissions fill the entire spectral region where interplanetary electromagnetic propagation is possible at wavelengths longer than infrared. Three distinct types of radiation are responsible for this radio spectrum. Thermal emission from the atmosphere accounts for virtually all the radiation at the high frequency end. Synchrotron emission from the trapped high-energy particle belt deep within the inner magnetosphere is the dominant spectral component from about 4000 to 40 MHz. The third class of radiation consists of several distinct components of sporadic low frequency emission below 40 MHz. The decimeter wavelength emission is considered, taking into account the discovery of synchrotron emission, radiation by high-energy electrons in a magnetic field, and the present status of Jovian synchrotron phenomenology. Attention is also given to the decameter and hectometer wavelength emission, and emissions at kilometric wavelengths.
281 citations
TL;DR: In this paper, it is predicted that there can be a new type of radiation of relativistic channeled particles, and a possibility of using this radiation in physics is indicated, in particular for creating a nuclear γ laser.
277 citations
TL;DR: In this paper, a quantitative analytical theory of jitter radiation was developed, which was applied to internal shocks of γ-ray bursts (GRBs), and it was shown that the emergent spectrum is determined by statistical properties of the magnetic field.
Abstract: We demonstrate that the radiation emitted by ultrarelativistic electrons in highly nonuniform, small-scale magnetic fields is different from synchrotron radiation if the electron's transverse deflections in these fields are much smaller than the beaming angle. A quantitative analytical theory of this radiation, which we refer to as jitter radiation, is developed. It is shown that the emergent spectrum is determined by statistical properties of the magnetic field. The jitter radiation theory is then applied to internal shocks of γ-ray bursts (GRBs). The model of a magnetic field in GRBs proposed by Medvedev & Loeb in 1999 is used. The spectral power distribution of radiation produced by the power-law-distributed electrons with a low-energy cutoff is well described by a sharply broken power law: P(ω) ∝ ω1 for ω ωjm and P(ω) ∝ ω-(p-1)/2 for ω ωjm, where p is the electron power-law index and ωjm is the jitter break frequency, which is independent of the field strength but depends on the electron density in the ejecta, ωjm ∝ n1/2, as well as on the shock energetics and kinematics. The total emitted power of jitter radiation is, however, equal to that of synchrotron radiation. Since large-scale fields may also be present in the ejecta, we construct a two-component, jitter + synchrotron spectral model of the prompt γ-ray emission. Quite surprisingly, this model seems to be readily capable of explaining several properties of time-resolved spectra of some GRBs, such as (1) the violation of the constraint on the low-energy spectral index called the synchrotron "line of death," (2) the sharp spectral break at the peak frequency, inconsistent with the broad synchrotron bump, (3) the evidence for two spectral subcomponents, and (4) possible existence of emission features called "GRB lines." We believe these facts strongly support both the existence of small-scale magnetic fields and the proposed radiation mechanism from GRB shocks. As an example, we use the composite model to analyze GRB 910503, which has two spectral peaks. At last, we emphasize that accurate GRB spectra may allow precise determination of fireball properties as early as several minutes after the explosion.
277 citations
TL;DR: The authors evaluated the effect on mammographic examinations of the use of synchrotron radiation to detect phase-perturbation effects, which are higher than absorption effects for soft tissue in the energy range of 15-25 keV.
Abstract: The authors evaluated the effect on mammographic examinations of the use of synchrotron radiation to detect phase-perturbation effects, which are higher than absorption effects for soft tissue in the energy range of 15-25 keV. Detection of phase-perturbation effects was possible because of the high degree of coherence of synchrotron radiation sources. Synchrotron radiation images were obtained of a mammographic phantom and in vitro breast tissue specimens and compared with conventional mammographic studies. On the basis of grades assigned by three reviewers, image quality of the former was considerably higher, and the delivered dose was fully compatible.
276 citations