215-meter-long Beamline at SPring-8 S. Goto a , K. Takeshita a , Y. - - PowerPoint PPT Presentation

Construction and Commissioning of a 215-meter-long Beamline at SPring-8

• S. Gotoa, K. Takeshitaa, Y. Suzukia, H. Ohashia, Y. Asanob, H. Kimuraa, T. Matsushitaa, N.

Yagia, M. Isshikia, H. Yamazakia, Y. Yonedab, K. Umetania, and T. Ishikawaa, c

aSPring-8/JASRI, Mikazuki, Hyogo 679-5198, Japan bSPring-8/JAERI, Mikazuki, Hyogo 679-5148, Japan cSPring-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

• pened 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

Biomedical imaging center

Experimental hutch 2 and 3 Distance from the source 220 m 200 m 180 m 160 m 140 m 120 m 120 m 100 m 80 m 60 m 40 m Dry pump Dry pump Beam monitor and gate valve Roots pump with dry pump

Arcade

400-mm-diameter shielded beam duct Front end Experimental hutch 1

Storage ring building

Optics hutch with standard transport channel and optics

Parts of the transport channel

Standard double-crystal monochromator and transport channel components in the optics hutch 100-meter-long transport channel covered by the arcade in the open (seen from the Biomedical imaging center to the Storage ring bulding) Dry pump at the end of the transport channel in the Biomedical imaging center 300-mm-wide and 50-mm-high Kapton window at the experimental hutch 2 with a large gate valve

Beamline performances

Calculated photon flux density

104 105 106 107 108 20 40 60 80 100 Photon energy (keV) Flux density (ph/s/mA/mm2) Si 111 refl., 44 m Si 311 refl., 44 m Si 511 refl., 44 m Si 111 refl., 211 m Si 311 refl., 211 m Si 511 refl., 211 m

Calculated on-axis photon flux density at experimental hutch 1 (44 m) and hutch 3 (211 m) through double-crystal monochromator and 0.75-mm-thick beryllium window. Measured densities were 10～80% of calculated.

Rocking curve

0.2 0.4 0.6 0.8 1

• 15
• 10
• 5

5 10 15

∆θ

(sec) Normalized intensity

Measured (1 mA, 5×12 mm2) Measured (89 mA, 5×12 mm2) Measured (89 mA, 1.5×1.5 mm2) Calculated

Rocking curves for Si 311 reflections of double-crystal monochromator for 10-keV photon energy. Measured curves were taken for various ring currents and incident beam sizes showing the broadning due to crystal deformation for wider beam and high current. Further tuning must be done!

300-mm-wide beam profile

0.2 0.4 0.6 0.8 1.0 1.2

• 200
• 150
• 100
• 50

50 100 150 200 Horizontal position (mm) Intensity (arb. units)

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

At experimental hutch 1 Sample: Murry meteorite (3 mm chip) Photon energy: 35 keV Detector: Gd2O2S with CCD Voxel size: 6 µm×6 µm×6 µm Exposure: 10 s/projection×360 projections (Courtesy of K. Uesugi)

Refraction-enhanced imaging

At experimental hutch 2 and 3 Sample: Lung of mouse Photon energy: 45 keV Sample-detector distance: 14 m Image width: 24 mm (pixel size 24 µm) Single shot image!

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 µm×100 µm)