Showing papers on "Synchrotron radiation published in 1983"

Handbook on synchrotron radiation

Abstract: Preface. 1. Synchrotron X-ray scattering studies of Langmuir films (J. Als-Nielsen and H. Mowald). 2. Coronary angiography project at the Photon Factory using a large monochromatic beam (K. Hyodo, K. Nishimura and M. Ando). 3. Optical and dielectric properties of materials relevant to biological research (M.W. Williams, E.T. Arakawa and T. Inagaki). 4. Crystal-structure analysis of biological macromolecules by synchrotron-radiation diffraction (H.D. Bartunik). 5. Fibre diffraction: collagen (A. Bigi and N. Roveri). 6. Scattering from non-crystalline systems (M.H.J. Koch). 7. Synchrotron radiation sources (W. Brefeld and P. Gurtler). 8. A Bragg reflection monochromator for synchrotron radiation angiography (G.S. Brown). 9. Trace element analysis by X-ray fluorescence (A. Iida and Y. Gohshi). 10. Medical applications of synchrotron radiation (J.C. Giacomini and H.J. Gordon). 11. Microradiography and microtomography (W. Graeff and K. Engelke). 12. NIKOS - non-invasive angiography at HASYLAB (W. Graeff and W.-R. Dix). 13. Radiobiological experiments in the X-ray region with synchrotron radiation (K. Hieda and T. Ito). 14. Synchrotron radiation for angiography, an overview (E. Rubenstein and R. Hofstadter). 15. X-ray microscopy (G. Schmahl and P.-C. Cheng). 16. UV spectroscopy (E.S. Stevens). 17. Anomalous X-ray scattering (H.B. Stuhrmann, G. Goerigk and B. Munk). 18. Detectors for angiography (A. Thompson). 19. Progress in X-ray synchrotron diffraction studies of muscle contraction (K. Wakabayashi and Y. Amemiya). 20A. Imaging apparatus and techniques for synchrotron radiation (H.D. Zeman). 20B. The processing of intravenous coronary angiograms produced by synchrotron radiation (H.D. Zeman). Author index. Subject index.

Phenomenology of magnetospheric radio emissions

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.

Infrared synchrotron radiation from electron storage rings.

Abstract: Simple and useful approximations, valid at infrared wavelengths, to the equations for synchrotron radiation are presented and used to quantify the brightness and power advantage of current synchrotron radiation light sources over conventional infrared broadband laboratory sources. The Daresbury Synchrotron Radiation Source (SRS) and the Brookhaven National Synchrotron Light Source (vacuum ultraviolet) [NSLS(VUV)] storage rings are used as examples in the calculation of the properties of infrared synchrotron radiation. The pulsed nature of the emission is also discussed, and potential areas of application for the brightness, power, and time structure advantages are presented. The use of infrared free electron lasers and undulators on the next generation of storage ring light sources is briefly considered.

Electrical and optical properties of black phosphorus single crystals

Abstract: Large single crystals of black phosphorus have been prepared by a large volume-high pressure technique at high temperature. Using the crystals, we have measured temperature dependences of the electrical conductivity and the Hall coefficient, the FIR cyclotron resonance absorption and the reflectance for synchrotron radiation. All samples obtained are p-type and the Hall mobility reaches 5×10 4 cm 2 v·sec around 20K. The anisotropies of the effective mass, the Hall mobility and the SOR reflectance along the three crystal directions, a, b, and c, have been observed.

Theory of NP 0532 pulsar radiation and the nature of the activity of the Crab Nebula

Abstract: Plasma processes in the magnetospheres of pulsars are considered. A self-consistent radiation model of the pulsar NP 0532 and the Crab Nebula is presented. It is based on the consideration of cyclotron instability in a relativistic electron-positron plasma in a strong magnetic field. This instability onsets near the light cylinder of pulsar NP 0532. The pitch-angle and energy distribution of particles, caused by cyclotron instability development is found. It is shown that X- and γ-ray radiation of the pulsar is explained by the synchrotron radiation of beam particles. The scattering of excited oscillations on plasma particles is responsible for nonzero pitch-angles of the latter. As a result, synchrotron radiation originates which is within optical frequencies. The synchrotron luminosity evaluated coincides with that observed for NP 0532 in that spectral region. Cyclotron waves are pumped to lower frequencies due to nonlinear scattering by plasma particles and leave the pulsar magnetosphere as observable radio waves.

An Energy-Dispersive Spectrometer for the Rapid Measurement of X-ray Absorption Spectra Using Synchrotron Radiation

Abstract: The design and evaluation of an energy-dispersive spectrometer to measure X-ray absorption spectra rapidly using a synchrotron-radiation source is presented. The method employs a cylindrically bent triangular crystal to focus and disperse a quasiparallel polychromatic X-ray beam onto the sample. The beam passing through the sample then diverges towards an X-ray detector where beam position can be correlated to energy. Both concentrated and dilute samples were measured on X-ray film and with an electronic linear photodiode array detector and the data analysed to determine the resolution obtained and the data quality. This method is shown to provide an efficient way to obtain high-quality EXAFS and absorption-edge data and should permit kinetic studies to be performed on small samples with good counting statistics. The method should find application in the fields of biophysics, chemistry and materials science.

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.

Synchrotron radiation x-ray fluorescence analysis

Abstract: A systematic study of the minimum detection limits obtainable with synchrotron radiation continuum excitation has been made for thin samples of 10 elements distributed across the periodic table. Energy dispersion and wavelength dispersion measurements are included; the results show that both techniques achieve comparable values, ranging from 10/sup -3/ to 10/sup -1/ /sup +/g/cm/sup 2/, where line interference is absent. With the very small primary beam used for the energy dispersion measurements, this represents absolute detectability of 10/sup -12/ to 10 /sup -10/ g, in reasonable agreement with theoretical predictions. 4 figures, 5 tables.

The discovery of synchrotron radiation

Abstract: Thirty-five years ago the electromagnetic radiation that results from the acceleration of electrons in a circular accelerator was observed for the first time in a 70-MeV synchrotron at the General Electric Research Laboratory in Schenectady, NY. In May 1981, an entire issue of Physics Today was devoted to synchrotron radiation, which is widely recognized as an important research tool for physicists, chemists, and biologists and perhaps in medicine as higher-energy synchrotrons and electron storage rings have been constructed. It seems timely to review the background of its discovery at this laboratory and to record the exact circumstances of the first visual observation and measurements of the radiation. Before discussing the first observation of synchrotron radiation from a laboratory machine it should be noted that for centuries man had been seeing synchrotron radiation from stars or galaxies without knowing that some of their light resulted from the acceleration of elementary particles in the large magnetic fields associated with astronomical objects. In 1898 Lienard' first pointed out that an electric charge moving in a circular path should radiate energy and he calculated the rate of radiation from the centripetal acceleration of an electron. The theory was extended subsequently by Schott,^ who received the Adams Prize in 1908 at Cambridge University for his essay, \"The Radiation from Electric Systems or Ions in Accelerated Motion and the Mechanical Reactions on their Motion which Arise from I t . \" Schott, attempting to provide the background for an electron theory of matter, calculated the amount and the angular distribution of radiation from relativistic electrons grouped in various ways in orbits of proposed atomic models.

Undulators as Sources of Synchrotron Radiation

Abstract: At the present time the first generation of facilities having electron storage rings designed for and dedicated to synchrotron radiation research are beginning operations in the US, Europe and Japan. The use of wigglers and undulators as enhanced sources of synchrotron radiation plays an important role at all these facilities. Moreover, recently there has been much activity in the design of the next generation machines, which will place even greater, and perhaps exclusive, emphasis on the use of wigglers and undulators. The operation of these insertion devices has been made even more attractive by advances in the design and construction of permanent magnet wigglers and undulators. This reliable and economical technology eliminates the need for more complex superconducting magnets, except to achieve very high magnetic fields for the production of hard photons from relatively low energy rings. We review the spectral properties of the radiation, emphasizing the complementary aspects of time- and frequency-domain analyses. We next study the brightness of the undulator source. Finally, we consider some limitations associated with operating an undulator in a storage ring.

Etude de la polarisation circulaire du rayonnement synchrotron dans la gamme des rayons X par diffraction sur un composé ferrimagnétique

Abstract: The reported experiment is based upon two phenomena: (1) synchrotron radiation, when observed at some tenths of milliradians from the orbital plane, is elliptically polarized; (2) the Bragg intensity diffracted by a ferro- or ferrimagnetic sample depends on the orientation of the magnetization relative to the incident and diffracted beams, by a term which is proportional to the circular polarization rate. A vertical-axis X-ray diffractometer was placed at the beam port D11 at LURE-DCI, the wavelength being 1.804 A. It can be moved vertically, so as to receive radiation with variable circular polarization. The sample, powdered Zn0.5Fe2.5O4, was magnetized in a horizontal direction by an electromagnet whose field is reversed every 20 s: the difference between the intensities diffracted with the field in the two directions was measured for three Bragg peaks and three polarization rates. The vertical position of the beam center, as well as the width of the source, were determined from the variation of the linear polarization versus the height; this polarization is obtained by the measurement of two Bragg peaks. The results agree with the theory as regards their signs and their absolute values, in the limits of the errors, which are about 20%.

X-rays from radio pulsars: the detection of PSR 1055-52

Abstract: The short-period pulsar PSR 1055-52 has been detected as a soft X-ray source in the course of an Einstein Observatory survey of radio pulsars. Its X-ray to radio luminosity ratio is about 10,000, although the X-rays are not modulated at the neutron star's rotation frequency. High spatial resolution observations suggest that a significant fraction of the emission comes from an extended region surrounding the pulsar. Several possible scenarios for the origin of both point and extended X-ray emission from isolated neutron stars are investigated: radiation from the hot stellar surface, from hot polar caps, and from an optically thick atmosphere, as well as from a circumstellar nebula emitting thermal bremsstrahlung or synchrotron radiation. It is concluded that the spatial, spectral, and temporal characteristics of this source are most consistent with a model in which relativistic particles generated by the pulsar are radiating synchrotron X-rays in the surrounding magnetic field; i.e., that PSR 1055 is embedded in a mini-Crab nebula. Observational tests of this hypothesis are suggested, and the implications of this result for pulsar evolution are briefly discussed.