[en] Two different types of insertion devices - undulators and wigglers - are described and compared. Each provides a periodic magnetic field that alters polarity, but whereas the spectral distribution from a wiggler is continuous and wide, the radiation of an undulator has spectrally narrow and discrete peaks. The distinction is determined by the deflection parameter. The energy spread in undulator peaks is calculated. Insertion device magnets and gap are discussed. Undulator tunability from gap variation is considered on a 6-GeV lattice and on a 7-GeV lattice. Also discussed is the angular distribution of power and the polarization from various sources

No abstract available

[en] The need for dedicated synchrotron radiation facilities based on insertion devices and a low emittance storage-ring has been recognized for many years. A facility optimized to produce x-rays from 1 to 100 keV is expected to dramatically enhance research capabilities in the areas of condense matter physics, material sciences, chemical sciences, and biological sciences, in addition to contributing in a major way to the industrial research. This goal will be accomplished by the construction of the Advanced Photon Source (APS) facility consisting of a 7-GeV positron storage-ring with 100 mA current and 35 straight-sections to accommodate insertion devices. The ring energy has been chosen so that a single undulator will provide radiation from 4 to 40 keV (using the first and the third harmonics) with 0.2% bandwidth. The low emittance of 7 x 10^-9 rad . m will provide hard-x-ray undulator radiation with very high brilliance (∼10¹⁸ to 10¹⁹ photons/(s mm² mrad²). (Construction is expected to begin in 1989 at Argonne National Laboratory.) This overview will mainly address the facility from the users' point-of-view

[en] At a fixed storage ring energy, the energy of the harmonics of an undulator can be shifted or ''tuned'' by changing the magnet gap of the device. The possible photon energy interval spanned in this way depends on the undulator period, minimum closed gap, minimum acceptable photon intensity and storage ring energy. The minimum magnet gap depends directly on the stay clear particle beam aperture required for storage ring operation. The tunability of undulators planned for the Advanced Photon Source with first harmonic photon energies in the range of 5 to 20 keV are discussed. The results of an analysis used to optimize the APS ring energy is presented and tunability contours and intensity parameters are presented for two typical classes of devices

[en] In this document we present the characteristics of the electromagnetic radiation from various types of sources on a 6-GeV storage ring. The sources include bending magnets, undulators and wigglers. The characteristics are compared with those of other synchrotron sources when operated at their design specifications. The influence of positron beam size on the brilliance is discussed, along with the power distribution from these sources. The goal of this document is to provide users with enough information on the behavior of radiation from a 6-GeV storage ring so that a dialogue can be established with the accelerator physicists and engineers to acheive an optimal design. 11 refs., 27 figs., 9 tabs

[en] Until recently it has been commonly accepted that small impurities of magnetic atoms were severely detrimental to superconductivity, and that superconductivity and long-range magnetic ordering could not occur in the same materials. In known binary and pseudo-binary compounds, this is still the case. However, many recent experiments on ternary superconductors have shown that the effects of magnetism are considerably more complex. In some cases, the addition of magnetic atoms has been found to enhance superconducting properties by increasing the superconducting critical field, without significantly lowering the transition temperature. In many cases, compounds will show both superconducting and long range magnetic ordering transitions. The destruction of superconductivity by ferromagnetic ordering and the coexistence of superconductivity with antiferromagnetic ordering is now well established. Hyperfine interaction measurements have played a significant role in the investigations of these materials, including measurement of the magnitude of the exchange interaction between rare-earth spin and conduction electron spin, elucidation of the mechanism for critical field enhancement, specification of crystalline field ground states, and studies of the nature of magnetic ordering

[en] In Moessbauer low temperature thermometry the temperature is determined from the relative intensities of the various hyperfine lines as these are affected by the temperature dependent Boltzman populations of the hyperfine levels in the resonant nuclei. One can perform either source experiments or those that make use of the nuclear polarization in the absorber. The second method is more advisable because the radioactive heating is much smaller. The present work is concerned with a fundamental difficulty in absorber thermometry which arises from the fact that the line intensity in a Moessbauer spectrum is also dependent on the absorber thickness, the dependence on that is not a linear one. It is demonstrated that if this thickness effect is not analyzed properly, the experimental results will yield erroneous temperature values, destroying the absolute nature of the Moessbauer thermometer

[en] This book is covered under the following headings: Insertion device sources and synchrotron facilities; Insertion device power; Time-resolved techniques; Polarization phenomena and novel optics; and New application and detectors

[en] In this document we present the characteristics of the electromagnetic radiation from various types of sources on the 7-GeV Advanced Photon Source (APS) storage ring. The sources include bending magnets, undulators, and wigglers. The characteristics are compared with those of other synchrotron sources when operated at their design specifications. The influence of positron beam size on the on-axis brilliance is discussed, along with the power distribution from these sources. The goal of this document is to provide users with enough information on the characteristics of radiation from the APS storage ring so that experiments can be efficiently planned. 23 refs., 20 figs., 8 tabs

[en] Theoretical development in the line shape calculation of Mossbauer resonance spectra involving spin relaxation effects is introduced. The ''eigenvalue'' procedure of calculating line shapes saves computational times by two orders of magnitude compared to traditional methods. This was illustrated by calculating the relaxation spectra of hemoglobin cyanide and a GAMMA₈ quartet electronic state. The ''white noise approximation'' involved in all the relaxation theory is discussed, and its limitations are pointed out. The theory without such an approximation is used to analyze the data for Cs₂NaYbCl₆