Rapid X-ray reflectivity measurement using a new liquid interface reflectometer at SPring-8

X-ray reflectivity measurements of liquid surfaces were demonstrated using a recently developed liquid interface reflectometer at SPring-8. The reflectometer, equipped with a two-dimensional hybrid pixel array detector (PILATUS), achieved x-ray reflectivity towards 10^-9 with an integration time at each angle of only 1 sec, offering enormous potential for rapid measurements. Time-resolved measurements at a time resolution of 1 min were performed on the adsorption process of a globular protein lysozyme on a water/air interface.     

Advancement of Hard X-ray Nano-focusing Ellipsoidal Mirror at SPring-8

Ellipsoidal mirror optics can produce a smaller, two-dimensional focus with diffraction-limited properties than is possible when using mirror optics in Kirkpatrick–Baez (K–B) geometry [1 P. Kirkpatrick and A.V. Baez, Journal of the Optical Society of America 38, 766–773 (1948).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]]. This is because ellipsoidal focusing mirrors can be designed such that they have a larger numerical aperture in the sagittal focusing direction as compared to that in the meridional focusing direction. Although ellipsoidal focusing mirrors have this crucial advantage over K–B optics, K–B optics are widely utilized as micro-/nano-focusing devices [2 H. Mimura, Nature Physics 6, 122–125 (2010).[Crossref], [Web of Science ®] , [Google Scholar]–8 H. Mimura, Nature Communications 5, 3539 (2014).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]] in synchrotron radiation facilities and X-ray free electron laser facilities [9 P. Emma, Nature Photonics 4, 641–647 (2010).[Crossref], [Web of Science ®] , [Google Scholar], 10 T. Ishikawa, Nature Photonics 6, 540–544 (2012).[Crossref], [Web of Science ®] , [Google Scholar]]. Figure 1 shows a schematic of focusing mirror optics; Figure 1(a) shows the ellipsoidal mirror and Figure 1(b) the K–B mirror arrangement. In K–B geometry, two mirrors with a one-dimensionally curved surface, such as an elliptical cylinder, are orthogonally arranged in tandem to reflect and focus light independently in a direction perpendicular to each other under grazing-incidence conditions. Ellipsoidal focusing mirrors, which can generate a two-dimensional focusing beam by a single reflection, have a highly sloped surface with a two-dimensional aspherical shape, when compared to elliptical-cylinder mirrors that are used for line-focusing in K–B geometry. In addition, surface shapes of nano-focusing mirrors must be fabricated with nanometer-level accuracy. Therefore, fabrication of ellipsoidal nano-focusing mirrors is extremely difficult. There are no reports on ellipsoidal nano-focusing mirrors in the hard X-ray region with superior performances to provide diffraction-limited beams.     

Large-Field X-ray Imaging at SPring-8 BL20B2

The medium-length (215 m) bending-magnet beamline 20B2 is allocated to medical applications and various X-ray micro imaging techniques (e.g., angiography, computed tomography, phase contrast imaging and diffraction topography) [1 S. Goto, Nuclear Instruments and Methods in Physics Research A 467–468, 682–685 (2001).[Crossref], [Web of Science ®] , [Google Scholar]]. The unique properties of BL20B2 are high spatial coherence (large coherent length) and its wide beam cross-section, which come from its long beam transport path and bending magnet light source. The horizontal angular aperture of BL20B2 is 1.5 mrad, as in all bending magnet beamlines at SPring-8. The horizontal beam width at the end station is larger than 300 mm for a 215 m beamline length.     

Experiment at SPring-8

The GeV photon beam at SPring-8 is produced by backward-Compton scattering of laser photons from 8 GeV electrons. The maximum energy of the photon will be above 3 GeV, and the beam intensity will be 10⁷ photons/sec. Polarization of the photon beam will be 100 % at the maximum energy with fully polarized laser photons. We report the outline of the quark nuclear physics project with this high-quality high-intensity beam.     

Soft-Tissue Imaging at SPring-8

During the last few decades, many scientific research areas have experienced remarkable progress in nanoscience and nanotechnology. In an even rather wider field, complex and smart materials are also often isolated as small crystallites, and they present serious difficulties in terms of being synthesized without fluctuations of their compositions or crystalline orientations. This particular interest in material characterization at rather small scales has considerably affected the design, manufacturing, and performance of advanced scientific instruments. In fact, when characterizing advanced materials, progress frequently refers to a new area of knowledge, to the need of seeing, measuring, and understanding objects at the nano- and mesoscopic scale.     

New high-dispersion high-resolution three-crystal X-ray spectrometer

A new kind of three-crystal spectrometer is designed. The first two crystals are set in antiparallel position which remains constant during measurement. The third crystal is rotated along the horizontal axis perpendicular to the beams leaving the second crystal. Diffraction planes of the first two crystals are assumed to be vertical. The plane of incidence of the third crystal is then also vertical. Since this inctrument permits greatly increased resolution and dispersion, no extreme mechanical precision is required.Cukrovarnická 10, Praha 6, Czechoslovakia.The author wishes to thank Dr. J. Bakovský, Dr. A. Fingerland, Dr. E. Krouský and ing. O. Renner for numerous discussions.     

Optimization of deconvolution in Compton profile measurements

The method of generalized least squares has been used to deconvolute the Compton profile measurements in nickel. The method depends on two arbitrary parameters namely the cut-off parameterK and the damping factor λ. This has been discussed and a method suggested to optimize the damping parameter.     

BL43IR at SPring-8 redirected

BL43IR at SPring-8 is overviewed regarding the beamline properties on the flux, the brilliance and the noise in comparison with the conventional thermal radiation (TR). The flux is comparable to the TR, and what makes the most of BL43IR is to utilize the high brilliance. We redirect our strategy to concentrate on the microscopes with highly brilliant infrared radiation from SPring-8 and attract the vast TR spectroscopy community.     

Undulator Development for SPring-8-II

After the construction of the X-ray free electron laser facility SACLA, which achieved first lasing in 2011 [1 T. Ishikawa, Nature Photon. 6, 540 (2012)[Crossref], [Web of Science ®] , [Google Scholar]] and has been successfully operated for nearly four years, SPring-8 has now turned to upgrading its storage ring to further enhance the light source performance in terms of brilliance. In this “SPring-8-II” project, a new lattice structure composed of five bending magnets has been chosen [2 SPring-8-II Conceptual Design Report (2014), available from http://rsc.riken.jp/pdf/SPring-8-II.pdf [Google Scholar]] in order to reduce the horizontal emittance, which, in turn, requires us to shorten the straight sections available for undulators by roughly 1 m. In addition, the electron energy will be reduced down to 6 GeV from the current 8 GeV for further reduction of the emittance. This upgrade plan is not necessarily compatible with the existing undulators in SPring-8 and thus most of them need to be replaced with new ones optimized for operation in the new ring in order to maximize the brilliance. This raises a number of technical challenges toward realization of SPring-8-II, including considerable reduction of the manufacturing cost and further shortening of the magnetic period of undulators. In this article, we report relevant R&;D activities to overcome these challenges, together with a new concept to enable a flexible polarization control, which is one of the important options in synchrotron radiation (SR) beamlines.     

Interfacial structure analysis of polymer laminate using SPring-8 X-ray microbeam

Interfacial structure of laminated polyethylene (PE)/polypropylene (PP) films was investigated by synchrotron X-ray microbeam. The X-ray microbeam (0.9 μm (vertical) × 1.7 μm (horizontal)) formed using a phase zone plate was irradiated on the cross-section of the laminated films. In order to irradiate X-ray microbeam in the direction perpendicular to the cross-section of the film sample, adjustment of the sample setting was performed by Thomson scattering method. The Thomson scattering intensity is proportional to the number of the irradiated electrons, so the irradiated position of the X-ray microbeam could be determined from the intensity profile with high spatial resolution. By changing the sample position, diffraction patterns could be obtained from the laminated films across the PE/PP interfacial region. The thickness of the interfacial region of the annealed laminate was estimated as 5 μm judging from the changes of the diffraction intensities from the PE crystallites to the PP ones. The interfacial thickness depended on the thermal treatment of the film. It was found that the adhesion strength of the PE/PP laminate increased with increasing the interfacial thickness. Both of PE and PP chains entangled each other during laminate processing. The entangled molecular chains play important role as anchoring effect at the PE/PP interdiffusion region. However, the phase separation progressed with further crystallization by annealing. Thus, the adhesion strength of the PE/PP laminate was considered to be influenced by the interfacial thickness.     

Cutting-edge Results on Energies and Catalysts at SPring-8

What is an industrial researcher expecting from the use of synchrotron radiation at SPring-8? It seems that there are two answers. One expectation is that he is able to explain convincingly to his customers a distinctive advantage of the developed product in a visible manner, and the other is that he investigates essential quality of materials by returning to the starting point when he is at a loss what to do in the process of his R&D; thus he can gain the opportunity of making a technical breakthrough in his R&D. This is because SPring-8 provides the most powerful synchrotron radiation currently available. As a result, a researcher can understand the chemical-bonding states of the material structure at the atomic and electronic levels by utilizing new analytical tools such as XAFS (X-ray Absorption Fine Structure) and XRD (X-ray Diffraction), etc.     

Infrared microspectroscopy station at BL43IR of SPring-8

BL43IR of SPring-8 has been constructed for the infrared materials researches, and it covers a wide spectral range from 100 to 20,000 cm⁻¹. The microspectroscopy station of this BL has a spatial resolution smaller than 10 μm in diameter in the mid-infrared region without apertures. This station had been mainly used within mid-infrared region, and its performance in the far-infrared region had not been tested. In this paper, we examined the capability of the microscope in the far-infrared region and the spatial resolution is found to be almost at the diffraction limit. The microspectroscopy station has been revealed to have a good performance for doing materials researches in all the spectral range available.     

A high-resolution neutron gravity spectrometer

The principle and possible layout of a novel type of spectrometer for very slow neutrons are described, where the maximum reach of the flight parabola is used for monochromatization and energy analysis. This spectrometer is expected to admit of a resolution of about 10^–8 eV. It could be used for very-high resolution quasi-elastic scattering, e.g. due to hyperfine splitting, or due to the slow fluctuations at phase transitions, in polymers and biological substances.Work supported by the German Bundesministerium für Forschung und Technologie     

A novel high-resolution interference spectrometer

A novel precision wavemeter is presented with a resolution of better than 0·01 nm. A Sagnac interferometer with two diffraction gratings forms the basis of the instrument. Using spatial heterodyning techniques and a CCD camera/frame grabber data acquisition system allows fast computer control and power spectrum analysis. The mode structure and mode hopping characteristics of a typical laser diode were examined as a function of diode injection current.     

Search for low-energy induced depletion of Hf at the SPring-8 synchrotron

Electromagnetic transitions within nuclei reflect specific aspects of nuclear structure. This is particularly true for metastable excited states, or isomers, like ¹⁷⁸Hf^m2 (T_1/2=31${\mathrm{T}}_{1/2}=31$ years, excitation energy 2446 keV). The interaction of external radiation with isomers can be used to study atomic and nuclear properties and, perhaps, to induce a release of the stored energy. Some experiments indicated that low-energy photons near the L₃ edge (9.561 keV) of hafnium could cause this to occur for ¹⁷⁸Hf^m2, but the lack of a viable physical model and null experiments by other groups have left these claims in doubt. The present work describes a new experiment to examine this process by closely duplicating the irradiation conditions in positive studies, but using a more advanced multi-detector γ array. No support for an induced depletion of ¹⁷⁸Hf^m2 by low-energy photons was obtained, with an upper limit for the integral cross section that is eight orders-of-magnitude below the reported value.     

Hadron and nuclear physics with inverse compton gamma-rays at SPring-8

A new facility for GeV γ-ray beams in an energy range of 1.5–2.4 GeV has been constructed for developing hadron physics at SPring-8. GeV γ-rays are produced via the inverse Compton scattering process, and are used to study the sub-nucleonic structure of nucleon via the productions of φ and K⁺ mesons. The recent experimental results to observe φ and K⁺ mesons are discussed to look for the physics in relation to strangeness quarks in baryon resonances. A new beam line for MeV γ-rays at SPring-8 to give new possibilities for the studies of the weak-strong coupling effects in nuclear mediums through the observation of parity violation is also discussed.     

Status of pump-probe time-resolved photoemission electron microscopy at SPring-8

The present status and the recent progress of pump-probe time-resolved photoemission electron microscopy at SPring-8 are introduced. Combining the variety of bunch operation modes available at the SPring-8 storage ring with ultra-short excitation sources including pulsed magnetic fields, electric fields and lasers, the element-specific time evolution of materials in response to the excitation can be observed with spatial and temporal resolutions of (50–300) nm and (40–100) ps, respectively, with repetition frequencies of up to 42 MHz. By using the magnetic circular dichroism effect, the domain motion of sub-micron sized magnetic areas can be observed. The time evolution of electronic structures in local areas can also be studied. The experimental setups and representative activities are described.     

Band tunable X-ray flat crystal spectrometer for laser-produced plasma spectroscopy measurements

An updated design of a band-tunable flat crystal spectrometer is presented. The new configuration contributes to a broad spectral coverage with greater resolving power, a strong rejection of hard X-ray backgrounds, and decreased sensitivity to source broadening for an extended source. To verify the performance of the spectrometer, spectral lines were measured using a potassium acid phthalate crystal for highly ionized species of aluminum or silicon, and the results were compared by measuring H- and He-like Al and Si lines by rotating the crystal to selected Bragg angles, at the Shenguang II laser facility. The observed energy-coverage range is consistent with the theoretical predictions, as well as with the measured spectral resolution of ~300.