Construction and Commissioning of a 215-meter-long Beamline at SPring-8 S. Goto a , K. Takeshita a , Y. Suzuki a , H. Ohashi a , Y. Asano b , H. Kimura a , T. Matsushita a , N. Yagi a , M. Isshiki a , H. Yamazaki a , Y. Yoneda b , K. Umetani a , and T. Ishikawa a, c a SPring-8/JASRI, Mikazuki, Hyogo 679-5198, Japan b SPring-8/JAERI, Mikazuki, Hyogo 679-5148, Japan c SPring-8/RIKEN, Mikazuki, Hyogo 679-5148, Japan
Abstract The 215-m-long beamline (BL20B2) has been constructed as the first medium-length beamline at SPring-8 for the purpose of R&D of imaging techniques, development of X-ray optics, computer tomography for mineral science, medical imaging, and X-ray topography . It has been opened to public users since October 1999. By using the long beamline, large field and spatially coherent beam can be obtained. At the end of the long beamline, ratio of sample-detector to source-sample can be set extremely small enabling to carry out high-spatial-resolution imaging .
Beamline features � Total length: 215 m � Front end: standard type for the bending-magnet beamline � Horizontal acceptance angles: 1.5 mrad � Transport channel in the optics hutch: standard type for the bending-magnet beamline � Monochromator SPring-8 standard double-crystal monochromator Position from the source: 36.8 m Energy range: 4.4 ～ 113 keV (using Si 111, 311, and 511 reflections) Cooling with heat contact InGa (1st crystal), 0.1-mm-thick In (2nd crystal) � 160-m-long transport to the Biomedical imaging center Diameter: 400 mm Shielding: 1-mm-thick lead Exhaust units: one roots pump and three dry pumps (No pump in the open) Ultimate vacuum pressure: 10 -2 Pa (Ohashi et al., in this conference) � Window at the end of the shielded ducts in the experimental hutch 2 200-mm-wide beryllium window / 300-mm-wide Kapton window
Transport channel of BL20B2 Storage ring building Roots pump with dry pump Optics hutch with standard transport channel and optics Beam monitor and Experimental hutch 1 gate valve Dry pump Front end 120 m 40 m 60 m 80 m 100 m Biomedical imaging center Dry pump 400-mm-diameter shielded beam duct Experimental hutch 2 and 3 Arcade 120 m 140 m 160 m 180 m 200 m 220 m Distance from the source
Parts of the transport channel Standard double-crystal monochromator and Dry pump at the end of the transport channel transport channel components in the optics hutch in the Biomedical imaging center 100-meter-long transport channel 300-mm-wide and 50-mm-high Kapton window covered by the arcade in the open at the experimental hutch 2 with a large gate valve (seen from the Biomedical imaging center to the Storage ring bulding)
Beamline performances Calculated photon flux density Rocking curve 10 8 1 Calculated Si 111 refl., 44 m Measured Si 311 refl., 44 m 0.8 (1 mA, 5 × 12 mm 2 ) Normalized intensity Flux density (ph/s/mA/mm 2 ) 10 7 Measured (89 mA, 1.5 × 1.5 mm 2 ) Si 511 refl., 44 m 0.6 Measured (89 mA, 5 × 12 mm 2 ) Si 111 refl., 211 m 10 6 0.4 Si 311 refl., 211 m 0.2 10 5 Si 511 refl., 211 m 0 -15 -10 -5 0 5 10 15 10 4 ∆θ (sec) 0 20 40 60 80 100 Photon energy (keV) Rocking curves for Si 311 reflections of Calculated on-axis photon flux density at double-crystal monochromator for 10-keV experimental hutch 1 (44 m) and hutch 3 (211 photon energy. Measured curves were taken for m) through double-crystal monochromator and various ring currents and incident beam sizes 0.75-mm-thick beryllium window. showing the broadning due to crystal Measured densities were deformation for wider beam and high current. 10 ～ 80% of calculated. Further tuning must be done!
300-mm-wide beam profile 1.2 1.0 Intensity (arb. units) 0.8 0.6 0.4 0.2 0 -200 -150 -100 -50 0 50 100 150 200 Horizontal position (mm) A 300-mm-wide direct beam image recorded by Imaging Plate at 201 m from the source point (upper) and intensity distribution in the horizontal direction for 15-keV photons from Si 311 reflection (lower). Non-uniformity of ± 20% was observed due to deformation of monochromator crystal. Further tuning must be done!
Preliminary results Computed tomography Refraction-enhanced imaging At experimental hutch 1 Sample: Murry meteorite (3 mm chip) At experimental hutch 2 and 3 Photon energy: 35 keV Sample: Lung of mouse Detector: Gd 2 O 2 S with CCD Photon energy: 45 keV Voxel size: 6 µ m × 6 µ m × 6 µ m Sample-detector distance: 14 m Exposure: 10 s/projection × 360 projections Image width: 24 mm (pixel size 24 µ m) Single shot image! (Courtesy of K. Uesugi)
Topograph of 300-mm-diameter silicon crystal At experimental hutch 2 Sample: 300-mm-diameter silicon crystal Photon energy: 21 keV 511 asymmetric reflection with glancing angle of 0.6 degrees Detector: Imaging Plate (pixel size 100 µ m × 100 µ m)
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