Super Photon Ring Research Articles

Determination of Residual Stress Distribution in Severe Surface Deformed Steel by Shot Peening

The compressive stress distribution below the specimen surface of a nanocrystalline medium carbon steel was investigated nondestructively by using high-energy X-rays from a synchrotron radiation source, SPring-8 (Super Photon ring-8 GeV) in the Japan Synchrotron Radiation Research Institute. A medium carbon steel plate was shot-peened with fine cast iron particles of the size of 50 μm. By using the monochromatic X-ray beam with three energy levels of 10, 30 and 72 keV, the stress values at the arbitrary depth were measured by the constant penetration depth method. The stress was calculated from the slope of the sin2ψ diagram. Measured stress corresponds to the weighted average associated with the attenuation of the X-rays in the material. The real stress distribution was estimated by using the optimization technique. The stress distribution was assumed by the third order polynomial in the near surface layer and the second order polynomial. The coefficients of the polynomials were determined by the conjugate gradient iteration. The predicted stress distribution agreed well with that measured by the conventional surface removal method.

Scientific opportunities in nuclear resonance spectroscopy from source-driven revolution

From the beginning of its discovery the Mossbauer effect has continued to be one of the most powerful tools with broad applications in diverse areas of science and technology. With the advent of synchrotron radiation sources such as the Advanced Photon Source (APS), the European Synchrotron Radiation Facility (ESRF) and the Super Photon Ring-8 (SPring-8), the tool has enlarged its scope and delivered new capabilities. The popular techniques most generally used in the field of materials physics, chemical physics, geoscience, and biology are hyperfine spectroscopy via elastic nuclear forward scattering (NFS), vibrational spectroscopy via nuclear inelastic scattering (NRIXS), and, to a lesser extent, diffusional dynamics from quasielastic nuclear forward scattering (QNFS). As we look ahead, new storage rings with enhanced brilliance such as PETRA-III under construction at DESY, Hamburg, and PEP-III in its early design stage at SLAC, Stanford, will provide new and unique science opportunities. In the next two decades, x-ray free-electron lasers (XFELs), based both on self-amplified spontaneous emission (SASE-XFELs) and a seed (SXFELs), with unique time structure, coherence and a five to six orders higher average brilliance will truly revolutionize nuclear resonance applications in a major way. This overview is intended to briefly address the unique radiation characteristics of new sources on the horizon and to provide a glimpse of scientific prospects and dreams in the nuclear resonance field from the new radiation sources. We anticipate an expanded nuclear resonance research activity with applications such as spin and phonon mapping of a single nanostructure and their assemblies, interfaces, and surfaces; spin dynamics; nonequilibrium dynamics; photochemical reactions; excited-state spectroscopy; and nonlinear phenomena.

Lower limits of detection of synchrotron radiation high-energy X-ray fluorescence spectrometry and its possibility for the forensic application for discrimination of glass fragments

Synchrotron radiation high-energy X-ray fluorescence (SR-XRF) analysis utilizing 75.5 keV X-ray radiation from beam-line BL37XU at Super Photon Ring 8 GeV (SPring-8), a third-generation synchrotron facility, was found to have advantages for forensic discrimination of glass samples. The lower limits of detection (LLD) for calibration curves were at the picogram level for Ba, Ce, and Sm and at the 10 pg level for Sr, Zr, Sn, and Hf. The spectrum of NIST SRM 612 glass reference material demonstrated K-line peaks of 31 elements including rare-earth elements, and the relative standard deviations (R.S.D.) of all the measured elements except Ca were less than 9.7%. Fragments of collected sheet glass were used as samples for investigating the application of this technique to forensic analysis. Several trace elements such as Pb, Rb, Sr, Zr, La, Ce, and Hf were detected in the spectra of the samples, and these elements could be used as indexes to characterize the glass samples. But the “lower limits of detection (LLD)” of each element were not examined enough. In this report, these limits by synchrotron radiation X-ray spectrometry were clarified. By these results, this technique should provide an effective approach to the nondestructive discrimination of small glass fragments in the field of forensic science.

Residual Stress Analysis in Lanthanum Gallate-based Cell before and after Fuel Cell Operation

The distribution of residual stress in the cells with the practical size of 120mm in diameter was measured by X-ray from synchrotron radiation at Super Photon ring 8 GeV (SPring-8). The residual stress was determined by the constant penetration depth method. When NiO-samaria doped ceria (SDC) was sintered on (La,Sr)(Ga,Mg,Co)O3-d (LSGMC), the tensile stresses resided in NiO and SDC, and the compressive stress was resided in LSGMC. The reduction of the anode by hydrogen decreased tensile stresses in the anode. The residual stresses in the electrodes did not change at any X-ray penetration depth.

Nondestructive Evaluation of Thermal Phase Growth in Solder Ball Microjoints by Synchrotron Radiation X-Ray Microtomography

In high-density packaging technology, one of the most important issues is the reliability of the microjoints connecting large scale integrated circuit chips to printed circuit boards electrically and mechanically. The development of nondestructive testing methods with high spatial resolution is expected to enhance reliability. An X-ray microtomography system called SP-μCT has been developed in Super Photon ring-8 GeV (SPring-8), the largest synchrotron radiation facility in Japan. In this work, SP-μCT was applied in the nondestructive evaluation of microstructure evolution, that is, the phase growth due to thermal cyclic loading in solder ball microjoints. Simulating solder microjoints used in a flip chip, specimens were fabricated by joining a Sn–Pb eutectic solder ball 100 μm in diameter to a steel pin in the usual reflow soldering process. The phase growth process was determined by observing the computed tomography (CT) images obtained consecutively at the fixed point of the target joining. In the reconstructed CT images, the distribution of the constituent phases in the Sn–Pb eutectic solder was identified based on the estimation value of the X-ray linear attenuation coefficient. Consequently, the microstructure images obtained nondestructively by SP-μCT provided us with the following useful information for evaluating the reliability of the solder microjoints. First, each phase involves not dispersing particles but a three-dimensional monolithic structure like a sponge. Second, the phase growth proceeds in such a way that the average phase size to the fourth power increases proportionally to the number of cycles. Finally, in the vicinity of the joining interface, more rapid phase growth occurs compared to the other regions because local thermal strain due to the mismatch of thermal expansion leads to a remarkable phase growth.

STUDY OF THE GATE INSULATOR/SILICON INTERFACE UTILIZING SOFT AND HARD X-RAY PHOTOELECTRON SPECTROSCOPY AT SPring-8

The chemical structures of SiO 2/ Si interfaces were studied by photoelectron spectroscopy using high-brilliance soft X-ray with photon energy ranging from 500 to 1500 eV at Super Photon ring 8 GeV(SPring-8) and it is able to probe a depth of about 1.2 to 3 nm with energy resolution of 100 meV. On the other hand, high-brilliance hard X-ray with photon energy ranging from 6 to 10 keV is able to probe a depth of about 8.5 to 12.5 nm with energy resolution of 100 meV. Hard photoelectron spectroscopy are particularly useful for studying the composition and the chemical structure of transition layer at high-k dielectric/silicon interface.

Temperature-dependent magnetic Compton scattering study of spin moments inCe(Fe0.94Ru0.06)2

The spin moments in a Ce(Fe 0 . 9 6 Ru 0 . 0 4 ) 2 sample at 20, 50, 70, 150, and 190 K have been determined from magnetic Compton scattering experiments. The measurements on polycrystalline samples were carried out on beamline BL08W at super photon ring 8 GeV (SPring-8), Japan with 274.46-keV elliptically polarized synchrotron radiations. It is seen that the variation of magnetic effect (deduced from the ratio of the magnetic to charge intensities) is consistent with the antiferromagnetic and paramagnetic transitions, as seen in resistivity and magnetization studies. The data is analyzed for temperature-dependent spin moment contributions from different magnetic electrons of Ru-doped CeFe 2 .

Angle-resolved XPS studies on transition layers at SiO 2/Si interfaces

Using the high-brilliance synchrotron radiation at super photon ring 8 (SPring-8) we determined the electron escape depths in approximately 1-nm-thick low-temperature oxide layers, which were formed on Si(1 1 1) at 300 °C using three kinds of atomic oxygen, and that in approximately 1-nm-thick thermally grown oxide layer formed in 1 Torr dry oxygen at 900 °C by measuring Si 2p photoelectron spectra at the photon energy of 1050 eV. The results indicated that the electron escape depths in the three kinds of low-temperature oxide layers were 13–21% smaller than that in the thermally grown oxide layer. Furthermore, the electron escape depth in the thermally grown oxide layer, whose thickness was close to that of the structural transition layer, was 19% smaller than that in bulk SiO 2.

A case study of the size-resolved individual particles collected at a ground-based site on the west coast of Japan during an Asian dust storm event

Abstract To investigate the nature of individual Asian dust storm particles, an intensive field measurement was carried out on the west coast of Japan during a dense Asian dust storm event in March 2002. The giant particles (>5 μm) marked 124 times higher number concentration in the Asian dust storm event than in a non-Asian dust storm period. For the quantification analysis of the ultratrace elements in the size-resolved individual particles, an X-ray microprobe system equipped with super photon ring-8 GeV (SPring-8) BL-39XU was employed. By using this SPring-8 system we could successfully carry out the reconstruction of elemental maps and the quantification analysis of multiple elements in individual particles. The mass of Si showing the maximum value in individual particles was varied in the range from 1.2×10−2 pg to 1.1×100 pg with median 1.4×10−1 pg. In the case of S, mass ranged from 1.6×10−2 pg to 6.7×10−2 pg with median 3.9×10−2 pg, while several minor trace elements like V, Cr, Cu, and Zn show relatively low masses. A strong particle-size dependency of elemental masses was found for all elements, in particular the elemental masses of soil-derived components showed the monomodal maximum values around 2.05–5.07 μm particle size. From the X-ray, fluorescence images replayed corresponding to individual particles, we could simply categorize the visualized particles into two groups, namely internally mixed particles and externally mixed particles. From the factor analysis with variables of each elemental mass in individual particles, 79% of total particle population was found to be modified by sea-salt and sulfur.

Single protein molecular dynamics determined with ultra-high precision

We have successfully observed dynamical Brownian motions in an individual protein molecule and other biological ones in real-time with one-hundredth the atomic-scale precision (picometer-scale precision) using X-rays of the super photon ring-8 (SPring-8).

Properties of the size-resolved and individual cloud droplets collected in western Japan during the Asian dust storm event

Abstract With the point of view of the removal mechanism of Asian dust storm particles, in order to study the physiochemical properties of clouds a field campaign was conducted in western Japan during the Asian dust storm event. The polymeric water absorbent film and collodion film replication techniques were employed in the measurements of size-fractionated precipitation cloud and individual cloud droplets, respectively. In addition, to investigate the source profiles of the elements retained in cloud samples, the original desert sand was collected. Particle-induced X-ray emission was applied for the elemental analysis of size-resolved cloud droplets and desert sand. Also for the quantification analysis of the ultra trace elements in residual particles in individual cloud droplets, the X-ray microprobe system equipped at Super Photon ring-8 GeV (SPring-8) BL-37XU was newly applied. Soil derived components like Si, Ca, and Fe show higher mass concentrations in small droplets ( 6.4 μm), while S and Cl dominate at droplet size larger than 20 μm. Three cloud samples have liquid water content ranging from 0.04 to 0.11 g m −3 . The number size distribution of droplets collected at cloud base is monomodal with the maximum level around 15 μm. The size distribution of cloud droplets is widespread (up to 60 μm). The droplet residues mainly consisting of crustal components were successively reconstructed as elemental maps by the X-ray fluorescence (XRF) microprobe analytical technique. From these XRF elemental maps, it can be understood that crustal components are significantly distributed on and/or in the residual particles in individual cloud droplets. The plotting of enrichment factors calculated from the elemental composition of original desert sand in China not only indicates the good correlationship between elemental masses in residual particles of cloud base droplets and those of precipitation cloud, but also classify elements into soil origin and non-soil origin. Mineral components were identified as the main components of dry residual particles in cloud droplets. These soil-origin elements account for up to 68% of the total elemental mass.

Three-dimensional diffusion of non-sorbing species in porous sandstone: computer simulation based on X-ray microtomography using synchrotron radiation

The diffusion pathways of porous sandstone were examined by a three-dimensional (3-D) imaging technique based on X-ray computed tomography (CT) using the SPring-8 (Super Photon ring-8 GeV, Hyogo, Japan) synchrotron radiation facility. The analysis was undertaken to develop better understanding of the diffusion pathways in natural rock as a key factor in clarifying the detailed mechanism of the diffusion of radionuclides and water molecules through the pore spaces of natural barriers in underground nuclear waste disposal facilities. A cylindrical sample (diameter 4 mm, length 6 mm) of sandstone (porosity 0.14) was imaged to obtain a 3-D image set of 4503 voxels=2.623 mm3. Through cluster-labeling analysis of the 3-D image set, it was revealed that 89% of the pore space forms a single large pore-cluster responsible for macroscopic diffusive transport, while only 11% of the pore space is made up of isolated pores that are not involved in long-range diffusive transport. Computer simulations of the 3-D diffusion of non-sorbing random walkers in the largest pore cluster were performed to calculate the surface-to-volume ratio of the pore, tortuosity (diffusion coefficient in free space divided by that in porous rock). The results showed that (i) the simulated surface-to-volume ratio is about 60% of the results obtained by conventional pulsed-field-gradient proton nuclear magnetic resonance (NMR) laboratory experiments and (ii) the simulated tortuosity is five to seven times larger than the results of laboratory diffusion experiments using non-sorbing I− and Br−. These discrepancies are probably attributed to the intrinsic sample heterogeneity and limited spatial resolution of the CT system. The permeability was also estimated based on the NMR diffusometry theory using the results of the random walk simulations via the Kozeny–Carman equation. The estimated permeability involved an error of about 20% compared with the permeability measured by the conventional method, suggesting that the diffusometry-based NMR well logging with gradient coils is applicable to the in-situ permeability measurement of strata. The present study demonstrated that X-ray CT using synchrotron radiation is a powerful tool for obtaining 3-D pore structure images without the beam-hardening artifacts inevitable in conventional CT using X-ray tubes.

Novel application of sputtered-sliced concentric multilayers to various optical elements for synchrotron radiation high-brilliance X-ray beamlines at SPring-8

Three new types of optical elements for the synchrotron radiation (SR) high-brilliance X-ray beamlines have been developed: (1) a spatial resolution test pattern for X-ray computed tomography (CT), (2) a spatial resolution test pattern for X-ray scanning microscopy, and (3) a condenser device for X-ray imaging microscopy. These optical elements are composed of concentric multilayers of alternating high-Z and low-Z material deposited on a wire substrate. The characteristics of these elements have been tested at the SR facilities of Super Photon ring-8 GeV.Optical element (1) yielded a pattern of alternating opaque and transparent concentric rings with a film thickness of 1 μm. For (2), the test pattern was shown to work well in the high-energy X-ray region at 28 keV.Use of the condenser device with optical element (3) produced an absorption contrast image of a test pattern without modulation by the coherence of the source. These optical elements may play important roles in the future development of various analytical areas with high spatial resolution in the high-energy X-ray region at the SR high-brilliance X-ray beamlines.

The nature of individual solid particles retained in size-resolved raindrops fallen in Asian dust storm event during ACE-Asia

Abstract To determine the physicochemical properties of individual solid particles retained in raindrops, the size-segregated raindrop sampling was carried out at ground-based site in Kyoto, Japan in Asian dust storm event during ACE-Asia. For the analysis of elemental components in individual solid particles, X-ray fluorescence microprobe system installed at Super Photon ring 8 GeV (SPring-8) BL-37XU was applied. Consequently interraindrop data of individual solid particles that are present inside the raindrops could be obtained. The number size distribution of individual solid particles scavenged by each raindrop size was compared to the calculated particle-scavenging coefficient (E). There was a good agreement between the calculated scavenging coefficient for particles and the measured number size distribution of particles with radius 1 μm. Elemental mass showing the peak at raindrops collected on 0.7 mm mesh size was varied as a function of raindrop size. The masses of crustal components and chlorine show significantly high level regardless of raindrop size. Individual residual particles were successfully classified into several factors as a function of raindrop size. The hygroscopic portions for S, Cl, K, and Ca in individual particles retained in size-segregated raindrop were determined. The mixed particles with crustal and sea-salt accounted for large fraction of particles retained in small raindrops. Whereas, in the case of large raindrops, the mixed residual particles with crustal and sulfur contributed to large portion. The results obtained from our study indicate that a large number of dust particles were incorporated into cloud droplets during their long-range transport and dust particles were effectively washed out by raindrops during rainfall event.

Novel application of sputtered-sliced concentric multilayers to various optical elements for synchrotron radiation high-brilliance X-ray beamlines at SPring-8

Three new types of optical elements for the synchrotron radiation (SR) high-brilliance X-ray beamlines have been developed: (1) a spatial resolution test pattern for X-ray computed tomography (CT), (2) a spatial resolution test pattern for X-ray scanning microscopy, and (3) a condenser device for X-ray imaging microscopy. These optical elements are composed of concentric multilayers of alternating high-Z and low-Z material deposited on a wire substrate. The characteristics of these elements have been tested at the SR facilities of Super Photon ring-8 GeV.Optical element (1) yielded a pattern of alternating opaque and transparent concentric rings with a film thickness of 1 μm. For (2), the test pattern was shown to work well in the high-energy X-ray region at 28 keV.Use of the condenser device with optical element (3) produced an absorption contrast image of a test pattern without modulation by the coherence of the source. These optical elements may play important roles in the future development of various analytical areas with high spatial resolution in the high-energy X-ray region at the SR high-brilliance X-ray beamlines.

Method for stabilizing beam intensity and energy in the SPring-8 linac

In any electron accelerator facilities, radio frequencies (RF) for a linear accelerator and a circular accelerator that includes a booster synchrotron ring and a storage ring are completely different. There is not necessarily a sub-harmonic relation of two RFs between a linear accelerator and a circular accelerator. It is, however, indispensable to obtain a synchronous relation between both RFs and the timing of the gun trigger signal with the increasing beam current and shortening of beam time width from an electron gun in a linear accelerator. For a synchronous timing system in any electron accelerator facilities, there is no choice but to assemble a complicated system with the frequency dividers and multipliers in order to realize the synchronous relation between both RFs and the gun trigger signal. To simplify the complicated synchronous timing system, we have developed a new synchronization method for the RFs of both linear and circular accelerators. The new synchronization system has been installed into the synchrotron radiation facility, SPring-8 (Super Photon ring 8 GeV), which consists of a 1-GeV linac, an 8-GeV booster synchrotron and an 8-GeV storage ring. A 2856 MHz RF for the 1-GeV linac was generated by the 508.58 MHz RF of the 8-GeV storage ring with the new synchronous timing system, and the emission and acceleration under the condition of the shortening the beam time width in the linac was carried out. Since the synchronous relation between both the RFs and the gun trigger signal was realized by using the new synchronous timing system, the time jitter between the gun trigger signal and the RF phase of 2856 MHz was significantly reduced and resulted in beam energy stabilization. The new synchronous timing system has been used for usual beam operations at SPring-8. This timing system has achieved time jitters of 3.5 ps (rms) and beam energy stability of 0.009% (rms) under the condition of completely synchronized two RFs and the gun trigger signal.

Temperature-dependent magnetic Compton scattering study of spin moments inCe(Fe0.96Ru0.04)2

The spin moments in a $\mathrm{Ce}({\mathrm{Fe}}_{0.96}{\mathrm{Ru}}_{0.04}{)}_{2}$ sample at 20, 50, 70, 150, and 190 K have been determined from magnetic Compton scattering experiments. The measurements on polycrystalline samples were carried out on beam line BL08W at super photon ring 8 GeV (SPring-8), Japan with 274.46-keV elliptically polarized synchrotron radiations. It is seen that the variation of magnetic effect (deduced from the ratio of the magnetic to charge intensities) is consistent with the antiferromagnetic and paramagnetic transitions, as seen in resistivity and magnetization studies. The data is analyzed for temperature-dependent spin moment contributions from different magnetic electrons of Ru-doped ${\mathrm{CeFe}}_{2}.$

Microscopic strain analysis of semiconductor crystals using a synchrotron X-ray microbeam

We have developed an X-ray microbeam with a narrow energy bandwidth and a small angular divergence in both horizontal and vertical directions normal to the X-rays. Utilizing synchrotron radiation from the so-called third-generation ring like SPring-8 (Super Photon ring, 8 GeV), the X-ray microbeam possesses sufficient photons even after beam size compression. Using the X-ray microbeam, we have demonstrated to measure very local and minute lattice strain in silicon materials after some wafer preparation processes or device fabrication processes. Local strain in an Si crystal around the SiO 2/Si film edge and also strain at silicon-on-insulator (SOI) interface have been measured as sample materials.

High-energy X-ray diffraction studies of non-crystalline materials

High-energy ( E ≥ 30 keV) X-ray diffraction with the latest generation synchrotron sources as well as the introduction of advanced insertion devices: wiggler and undulator, has created new approaches to the quantitative study of the structure of non-crystalline materials because of several improvements: higher resolution in real space due to a wide range of Q, smaller correction terms (especially for absorption correction), reduction of truncation errors, the feasibility of running under extreme environments, including high-temperatures and high-pressures, and of obtaining a direct comparison between X-ray and neutron diffraction data. Recently, this technique has been combined with neutron diffraction with a pulsed source to provide more detailed and reliable structural information not previously available. This article reviews and summarizes recent results obtained from high-energy X-ray diffraction on several oxide glasses: SiO 2, B 2O 3, MgP 2O 6 and PbSiO 3, using bending magnet beamlines at Super Photon ring-8 (GeV) (SPring-8). In particular, it addresses the structural models of oxide glasses obtained by the reverse Monte Carlo (RMC) modelling technique using both the high-energy X-ray and neutron diffraction data.

放射光Ｘ線結晶学で今何ができるか？ これからの放射光利用 ＳＰｒｉｎｇ‐８利用に期待すること（ＳＰｒｉｎｇ‐８とＸ線結晶学）

Highest bright source in the world is available for X-ray Crystallography at Super Photon Ring with 8Gev (SPring-8) located at Nishiharima. For the last decade synchrotron source has promoted the research activities in the fields of crystallography, solid state physics, bioscience and geoscience. Furthermore, SPring-8 offers indescribable dreams to these sciences. Performance in X-ray crystallography using this facility will be beyond expression. From the view points of electron density, enharmonic thermal vibration and several others, possible future in X-ray crystallography using SPring-8 is described in this paper.