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At least 19 records

Comparison between ūu and d̄d productions by the γp → π{sup −}Δ{sup ++} and π{sup +}Δ{sup 0} reactions at forward π angles at E{sub γ} = 1.5–3.0 GeV

Photoproduction reactions are dominated by isospin rules. In the case of πΔ photoproduction on the proton at forward π angles, the exchange of isospin = 1 meson(π or ρ) in the t-channel is the most dominant reaction mechanism, which is considered to give a cross section ratio σ(π{sup +}Δ{sup 0})/σ(π{sup −}Δ{sup ++}) of 1/3. The cross section ratio has not been measured precisely experimentally. We present preliminary results for the cross section ratio at E{sub γ} = 1.5–3.0 GeV. Larger ratios than 1/3 measured by our experiment at LEPS/SPring-8 suggest that the d̄d productions are enhanced compared with the ūu productions in the photoproduction reactions on the proton.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Hard X-ray nanofocusing using adaptive focusing optics based on piezoelectric deformable mirrors

An adaptive Kirkpatrick–Baez mirror focusing optics based on piezoelectric deformable mirrors was constructed at SPring-8 and its focusing performance characteristics were demonstrated. By adjusting the voltages applied to the deformable mirrors, the shape errors (compared to a target elliptical shape) were finely corrected on the basis of the mirror shape determined using the pencil-beam method, which is a type of at-wavelength figure metrology in the X-ray region. The mirror shapes were controlled with a peak-to-valley height accuracy of 2.5 nm. A focused beam with an intensity profile having a full width at half maximum of 110 × 65 nm (V × H) was achieved at an X-ray energy of 10 keV.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Fluence thresholds for grazing incidence hard x-ray mirrors

X-ray Free Electron Lasers (XFELs) have the potential to contribute to many fields of science and to enable many new avenues of research, in large part due to their orders of magnitude higher peak brilliance than existing and future synchrotrons. To best exploit this peak brilliance, these XFEL beams need to be focused to appropriate spot sizes. However, the survivability of X-ray optical components in these intense, femtosecond radiation conditions is not guaranteed. As mirror optics are routinely used at XFEL facilities, a physical understanding of the interaction between intense X-ray pulses and grazing incidence X-ray optics is desirable. We conducted single shot damage threshold fluence measurements on grazing incidence X-ray optics, with coatings of ruthenium and boron carbide, at the SPring-8 Angstrom compact free electron laser facility using 7 and 12 keV photon energies. The damage threshold dose limits were found to be orders of magnitude higher than would naively be expected. The incorporation of energy transport and dissipation via keV level energetic photoelectrons accounts for the observed damage threshold.

43 PARTICLE ACCELERATORS↗

Analysis system of submicron particle tracks in the fine-grained nuclear emulsion by a combination of hard x-ray and optical microscopy

Analyses of nuclear emulsion detectors that can detect and identify charged particles or radiation as tracks have typically utilized optical microscope systems because the targets have lengths from several μm to more than 1000 μm. For recent new nuclear emulsion detectors that can detect tracks of submicron length or less, the current readout systems are insufficient due to their poor resolution. In this study, we developed a new system and method using an optical microscope system for rough candidate selection and the hard X-ray microscope system at SPring-8 for high-precision analysis with a resolution of better than 70 nm resolution. Furthermore, we demonstrated the analysis of submicron-length tracks with a matching efficiency of more than 99% and position accuracy of better than 5 μm. This system is now running semi-automatically.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

X-ray Compton scattering experiments for fluid alkali metals at high temperatures and pressures

We have developed a high-pressure vessel and a cell for x-ray Compton scattering measurements of fluid alkali metals. Measurements have been successfully carried out for alkali metal rubidium at elevated temperatures and pressures using synchrotron radiation at SPring-8. The width of Compton profiles (CPs) of fluid rubidium becomes narrow with decreasing fluid density, which indicates that the CPs sensitively detect the effect of reduction in the valence electron density. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 10 September 2015. The original article supplied to AIP Publishing was not the final version and contained PDF conversion errors in Formulas (1) and (2). The errors have been corrected in the updated and re-published article.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Three-dimensional structure of brain tissue at submicrometer resolution

Biological objects are composed of submicrometer structures such as cells and organelles that are essential for their functions. Here, we report on three-dimensional X-ray visualization of cells and organelles at resolutions up to 100 nm by imaging microtomography (micro-CT) equipped with Fresnel zone plate optics. Human cerebral tissue, fruit fly cephalic ganglia, and Escherichia coli bacteria labeled with high atomic-number elements were embedded in epoxy resin and subjected to X-ray microtomography at the BL37XU and BL47XU beamlines of the SPring-8 synchrotron radiation facility. The obtained results indicated that soft tissue structures can be visualized with the imaging microtomography.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗

Development of high-resolution x-ray CT system using parallel beam geometry

For fine three-dimensional observations of large biomedical and organic material samples, we developed a high-resolution X-ray CT system. The system consists of a sample positioner, a 5-μm scintillator, microscopy lenses, and a water-cooled sCMOS detector. Parallel beam geometry was adopted to attain a field of view of a few mm square. A fine three-dimensional image of birch branch was obtained using a 9-keV X-ray at BL16XU of SPring-8 in Japan. The spatial resolution estimated from the line profile of a sectional image was about 3 μm.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Non-invasive airway health measurement using synchrotron x-ray microscopy of high refractive index glass microbeads

Cystic fibrosis (CF) is caused by a gene defect that compromises the ability of the mucociliary transit (MCT) system to clear the airways of debris and pathogens. To directly characterise airway health and the effects of treatments we have developed a synchrotron X-ray microscopy method that non-invasively measures the local rate and patterns of MCT behaviour. Although the nasal airways of CF mice exhibit the CF pathophysiology, there is evidence that nasal MCT is not altered in CF mice1. The aim of this experiment was to determine if our non-invasive local airway health assessment method could identify differences in nasal MCT rate between normal and CF mice, information that is potentially lost in bulk MCT measurements. Experiments were performed on the BL20XU beamline at the SPring-8 Synchrotron in Japan. Mice were anaesthetized, a small quantity of micron-sized marker particles were delivered to the nose, and images of the nasal airways were acquired for 15 minutes. The nasal airways were treated with hypertonic saline or mannitol to increase surface hydration and MCT. Custom software was used to locate and track particles and calculate individual and bulk MCT rates. No statistically significant differences in MCT rate were found between normal and CF mouse nasal airways or between treatments. However, we hope that the improved sensitivity provided by this technique will accelerate the ability to identify useful CF lung disease-modifying interventions in small animal models, and enhance the development and efficacy of proposed new therapies.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Recent progress of hard x-ray imaging microscopy and microtomography at BL37XU of SPring-8

A hard x-ray imaging microscopy and microtomography system is now being developed at the beamline 37XU of SPring-8. In the latest improvement, a spatial resolution of about 50 nm is achieved in two-dimensional imaging at 6 keV x-ray energy using a Fresnel zone plate objective with an outermost zone width of 35 nm. In the tomographic measurement, a spatial resolution of about 100 nm is achieved at 8 keV using an x-ray guide tube condenser optic and a Fresnel zone plate objective with an outermost zone width of 50 nm.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Imaging properties and its improvements of scanning/imaging x-ray microscope

A scanning / imaging X-ray microscope (SIXM) system has been developed at SPring-8. The SIXM consists of a scanning X-ray microscope with a one-dimensional (1D) X-ray focusing device and an imaging (full-field) X-ray microscope with a 1D X-ray objective. The motivation of the SIXM system is to realize a quantitative and highly-sensitive multimodal 3D X-ray tomography by taking advantages of both the scanning X-ray microscope using multi-pixel detector and the imaging X-ray microscope. Data acquisition process of a 2D image is completely different between in the horizontal direction and in the vertical direction; a 1D signal is obtained with the linear-scanning while the other dimensional signal is obtained with the imaging optics. Such condition have caused a serious problem on the imaging properties that the imaging quality in the vertical direction has been much worse than that in the horizontal direction. In this paper, two approaches to solve this problem will be presented. One is introducing a Fourier transform method for phase retrieval from one phase derivative image, and the other to develop and employ a 1D diffuser to produce an asymmetrical coherent illumination.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Upgrading multilayer zone plate technology for hard x-ray focusing

Multilayer zone plate (MZP) technology for hard X-ray focusing was upgraded and its focusing performance was evaluated using 20-keV X-rays at the synchrotron beamline (BL24XU) of SPring-8. The MZP consists of MoSi{sub 2} and Si layers alternately deposited on a glass fiber by magnetron sputtering so that all zone boundaries satisfy the Fresnel zone configuration. The focused beam was evaluated using knife-edge scanning in which the measured intensity distribution is identical to the line spread function (LSF) in the focal plane. The focused beamsize of about 30 nm was estimated by oscillation peaks observed in the measured LSF according to Rayleigh’s criterion.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Development of sealed sample containers and high resolution micro-tomography

A sample container and a high resolution micro-tomography system have been developed at BL47XU at SPring-8. The container is made of a SiN membrane in a shape of truncated pyramid, which makes it possible to exclude oxygen and moisture in the air. The sample rotation stage for tomography is set downward to keep the sample in the container without any glue. The spatial resolution and field of view are 300 nm and 110 μm using a Fresnel zone plate objective with an outermost zone width of 100 nm at 8 keV, respectively. The scan time is about 20 minutes for 1800 projections. A 3-D image of an asteroid particle was successfully obtained without adhesive and contamination.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Progress of projection computed tomography by upgrading of the beamline 37XU of SPring-8

Beamline 37XU at SPring-8 has been upgraded for nano-focusing applications. The length of the beamline has been extended to 80 m. By utilizing this length, the beamline has advantages for experiments such as X-ray focusing, X-ray microscopic imaging and X-ray computed tomography. Projection computed tomography measurements were carried out at experimental hutch 3 located 80 m from the light source. CT images of a microcapsule have been successfully obtained with a wide X-ray energy range.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

TAKASAGO-6 apparatus for cryogenic coherent X-ray diffraction imaging of biological non-crystalline particles using X-ray free electron laser at SACLA

Coherent X-ray diffraction imaging (CXDI) is a technique for structure analyses of non-crystalline particles with dimensions ranging from micrometer to sub-micrometer. We have developed a diffraction apparatus named TAKASAGO-6 for use in single-shot CXDI experiments of frozen-hydrated non-crystalline biological particles at cryogenic temperature with X-ray free electron laser pulses provided at a repetition rate of 30 Hz from the SPring-8 Angstrom Compact free-electron LAser. Specimen particles are flash-cooled after being dispersed on thin membranes supported by specially designed disks. The apparatus is equipped with a high-speed translation stage with a cryogenic pot for raster-scanning of the disks at a speed higher than 25 μm/33 ms. In addition, we use devices assisting the easy transfer of cooled specimens from liquid-nitrogen storages to the cryogenic pot. In the current experimental procedure, more than 20 000 diffraction patterns can be collected within 1 h. Here we report the key components and performance of the diffraction apparatus. Based on the efficiency of the diffraction data collection and the structure analyses of metal particles, biological cells, and cellular organelles, we discuss the future application of this diffraction apparatus for structure analyses of biological specimens.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Damage threshold of coating materials on x-ray mirror for x-ray free electron laser

We evaluated the damage threshold of coating materials such as Mo, Ru, Rh, W, and Pt on Si substrates, and that of uncoated Si substrate, for mirror optics of X-ray free electron lasers (XFELs). Focused 1 μm (full width at half maximum) XFEL pulses with the energies of 5.5 and 10 keV, generated by the SPring-8 angstrom compact free electron laser (SACLA), were irradiated under the grazing incidence condition. The damage thresholds were evaluated by in situ measurements of X-ray reflectivity degradation during irradiation by multiple pulses. The measured damage fluences below the critical angles were sufficiently high compared with the unfocused SACLA beam fluence. Rh coating was adopted for two mirror systems of SACLA. One system was a beamline transport mirror system that was partially coated with Rh for optional utilization of a pink beam in the photon energy range of more than 20 keV. The other was an improved version of the 1 μm focusing mirror system, and no damage was observed after one year of operation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Stitching methods at the European Synchrotron Radiation Facility (ESRF)

X-ray mirror quality has continuously improved over the past 20 years and manufacturers are now able to provide long mirrors with slope errors below 0.2 μrad. Nevertheless, these mirrors are mounted on holders or even mechanical benders to adjust their curvature and their intrinsic quality must be preserved from any parasitic deformation such as twist. The most direct method of detecting these deformations is to measure the 3D topography of the optical surface. At the ESRF metrology laboratory, three different stitching systems are under development based on Fizeau sub-aperture measurements. The first one consists of measuring long flat mirrors, the second based on the relative angle determinable stitching interferometry (RADSI) method developed at SPring-8 is aimed primarily at the measurement of short mirrors with strong curvature down to a few meters, and the last, also based on the RADSI method, is dedicated to characterize longer mirrors with intermediate curvature. For each method we will describe the measurement setup and discuss first results obtained. Micro-stitching interferometry is also currently used at the ESRF metrology laboratory. The technique is suitable for measuring deeply curved aspherical profiles and will be illustrated with results from a Kirkpatrick-Baez mirror system for nano-focusing.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Toward operation of series IDs at BL43LXU of SPring-8

This paper discusses two issues relating to using 3 small gap insertion devices in series at BL43LXU of SPring-8 to make a uniquely powerful source in the 15-26 keV region of the x-ray spectrum. The issues discussed are (1) damage to the covers of the downstream IDs by radiation from the upstream IDs and (2) proper steering of the electron beam to get the best photon beam properties. After tests in several configurations, including one where an ID was run without an impedance-reducing cover, the damage issue was solved by installing a distributed absorber in the most downstream ID. The steering issues were mostly resolved by the introduction of appropriate corrector magnets and feedback. The paper is written from the viewpoint of an interested beamline scientist impressed with the cooperation of different groups to make a source for new science possible.

43 PARTICLE ACCELERATORS↗

High-throughput and automated SAXS/USAXS experiment for industrial use at BL19B2 in SPring-8

A highly automated system combining a sample transfer robot with focused SR beam has been established for small-angle and ultra small-angle X-ray scattering (SAXS/USAXS) measurement at BL19B2 for industrial use of SPring-8. High-throughput data collection system can be realized by means of X-ray beam of high photon flux density concentrated by a cylindrical mirror, and a two-dimensional pixel detector PILATUS-2M. For SAXS measurement, we can obtain high-quality data within 1 minute for one exposure using this system. The sample transfer robot has a capacity of 90 samples with a large variety of shapes. The fusion of high-throughput and robotic system has enhanced the usability of SAXS/USAXS capability for industrial application.

43 PARTICLE ACCELERATORS↗