| Project/Area Number |
23K28346
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| Project/Area Number (Other) |
23H03657 (2023)
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Multi-year Fund (2024)
Single-year Grants (2023) |
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| Section | 一般 |
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| Review Section |
Basic Section 80040:Quantum beam science-related
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| Research Institution | Tokyo Gakugei University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
工藤 博幸 筑波大学, システム情報系, 教授 (60221933)
白澤 徹郎 国立研究開発法人産業技術総合研究所, 計量標準総合センター, 主任研究員 (80451889)
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| Project Period (FY) |
2023-04-01 – 2026-03-31
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| Project Status |
Granted (Fiscal Year 2024)
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| Budget Amount *help |
¥18,460,000 (Direct Cost: ¥14,200,000、Indirect Cost: ¥4,260,000)
Fiscal Year 2025: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
Fiscal Year 2024: ¥9,750,000 (Direct Cost: ¥7,500,000、Indirect Cost: ¥2,250,000)
Fiscal Year 2023: ¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000)
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| Keywords | X-ray CT / X-ray tomography / Time-resolved / Synchrotron radiation / Multibeam CT |
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| Outline of Research at the Start |
Synchrotron radiation computed tomography (CT) is widely used to visualize internal structures three-dimensionally, but for time-resolved observations standard methods are hampered by the necessity to rotate the sample. The multibeam CT method, which images the sample using multiple X-ray beams, does not suffer from this problem. In this research, a multibeam CT instrument that can be used with high-brightness synchrotron radiation sources will be developed and demonstrated, in order to achieve a combination of high temporal resolution and spatial and density resolutions.
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| Outline of Annual Research Achievements |
Synchrotron radiation computed tomography (CT) can visualize internal structures three-dimensionally with high spatial resolution. The novel multibeam CT method enables us to avoid rotation of the sample or detector that is necessary in standard CT methods. In this research, a multibeam CT instrument that can be used with high-brightness synchrotron radiation sources is developed and demonstrated, in order to achieve a combination of high temporal resolution and spatial and density resolutions.
A focus of the research in FY2023 was the development of the X-ray optical system for the multibeam CT instrument. Test results of prototype optical systems for white synchrotron radiation and quasi-monochromatic synchrotron were analyzed, showing the feasibility of the design concept. Based on the results, an optical system optimized for a synchrotron radiation beamline was designed, fabricated and tested. In parallel, development towards the next generation optics using a beam splitter made of a single crystal was conducted. It was found that such an optical system can be realized and has advantages.
To achieve the highest possible time resolutions, the analysis of the tomography data necessitates innovative reconstruction methods bases on compressed sensing. The research has found that an advanced reconstruction method called ABD-CT (ABnormal data Detected CT) gives excellent performance for data with a small number of projection data and abnormal data values due to statistical noise, being superior to more conventional compressed sensing methods.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The development of the multibeam optical system has proceeded as planned; analyzing and publishing results of two prototype optical systems, and developing an optimized optical system. The use of a beam splitter in combination with the multibeam optical system is very promising to increase the X-ray intensity of high-angle beams, but development was expected to be challenging. Results have shown the feasibility of the concept, so we are planning to focus on this type of optics in the next fiscal year.
Regarding the data analysis, it was proved that the compressed-sensing-based ABD-CT method is very effective for high-quality reconstruction of the tomographic data produced by the optical systems. The data fidelity term plays a key role in this method, and it was found that the L0 norm is superior to the L1 norm, with both outperforming standard compressed sensing. This is an important milestone for achieving high temporal resolutions.
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| Strategy for Future Research Activity |
In FY 2024, the research will focus on the following four topics:
1. An X-ray beam splitter will be developed and tested. The multibeam optics developed in this research uses diffraction at a set of silicon single crystals with different angles to be able to image the sample simultaneously from many directions. Based on the results of FY2023, a high-efficiency beam splitter using on diffraction at a single crystal will be developed, which is expected to help with achieving high time resolutions. An important point is to use a crystal that can diffract a comparatively wide energy bandwidth, but not so wide that the spatial resolution is degraded.
2. Multibeam optics using a beam splitter will be developed and tested. The first task is to design the optical system. This optical system will then be aligned and tested using synchrotron radiation. If the research proceeds well, work for combining the optical system with a detection system capable of observing all beams simultaneously will be conducted.
3. Results of FY2023 showed the power of the ABD-CT method for reconstruction of tomographic data sets with a limited number of projections and a low signal-noise ratio in some projection angles. It will be applied for data reconstruction and further improved in FY2024. Advanced tomographic reconstruction methods will be developed and/or improved, for example for sparse-view CT or interior CT.
4. Exploratory research regarding the use of the multibeam method to obtain information about the local atomic environment of a selected element will be conducted as well.
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