IPAC2018 - List of Authors (Ohgaki, H.)

Paper	Title	Page
MOPML049	Generation of 1-MeV Quasi-Monochromatic Gamma-Rays for Precise Measurement of Delbrück Scattering by Laser Compton Scattering	508
	H. Zen, T. Kii, H. Ohgaki Kyoto University, Kyoto, Japan M. Fujimoto, M. Katoh, E. Salehi UVSOR, Okazaki, Japan T. Hayakawa, T. Shizuma QST, Tokai, Japan M. Katoh Sokendai - Okazaki, Okazaki, Aichi, Japan J. Koga National Institutes for Quantum and Radiological Science and Technology, Kyoto, Japan E. Salehi AUT, Tehran, Iran
	Delbrück scattering is the elastic scattering of photons by the electromagnetic field of an atomic nucleus, as a consequence of vacuum polarization. The isolated measurement of Delbrück scattering has not been performed because of interference with other elastic scattering processes. It was recently discovered that, using linearly polarized photons, Delbrück scattering can be measured nearly independently of the other scattering processes. In order to perform a proof of principle experiment, a quasi-monochromatic gamma-ray beam with a maximum photon energy of 1 MeV has been generated at the UVSOR facility by colliding a CO2 laser with a 750-MeV electron beam. A preliminary experiment has been performed with 0.5-W laser power and 1-mA electron beam current. As a result, the measured gamma-ray flux was evaluated as 0.0006 photon/eV/mA/W/s around the peak energy of 1 MeV. If we accept 20 percent energy spread, in case of a 100-W CO2 laser colliding with a 300 mA electron beam, approximately 4 x 10⁶-photons/s gamma-rays could be obtained. This flux is sufficiently high for the proof of principle experiment. J.K. Koga and T. Hayakawa, Phys. Rev. Lett. 118, 204801 (2017).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML049
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THPMF074	Study of the Saturation of Radiation Energy Caused by the Space Charge Effect in a Compact THz Coherent Radiation Source	4245
SUSPF018	use link to see paper's listing under its alternate paper code
	S. Krainara, Chatani, S. Chatani, T. Kii, H. Ohgaki, H. Zen Kyoto University, Kyoto, Japan
	Funding: Institute of Advanced Energy, Kyoto University To generate an intense quasi-monochromatic Terahertz Coherent Undulator Radiation (THz-CUR), a compact linac system, which employs a magnetic electron bunch compressor with a beam energy of 4.6 MeV, has been constructed at Kyoto University. The THz-CUR has suc-cessfully been generated in a frequency range from 0.16 to 0.65 THz with a bunch charge of 60 pC. The maximum micro-pulse energy of THz radiation was observed higher than 1 μJ at 0.16 THz with 160 pC. However, when a bunch charge was higher than 80 pC, the micro-pulse energy of THz radiation gradually went to the saturation and obviously at the bunch charge higher than 110 pC because of the bunch lengthening and degradation of electron beam quality due to the space charge effect. The dependence of a bunch length on a bunch charge has been studied by GPT simulation and compared with CTR and CUR experiments. The trends of the measured results from CUR and CTR are in good agreement with the GPT simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF074
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Paper

Title

Page

Generation of 1-MeV Quasi-Monochromatic Gamma-Rays for Precise Measurement of Delbrück Scattering by Laser Compton Scattering

508

H. Zen, T. Kii, H. Ohgaki
Kyoto University, Kyoto, Japan
M. Fujimoto, M. Katoh, E. Salehi
UVSOR, Okazaki, Japan
T. Hayakawa, T. Shizuma
QST, Tokai, Japan
M. Katoh
Sokendai - Okazaki, Okazaki, Aichi, Japan
J. Koga
National Institutes for Quantum and Radiological Science and Technology, Kyoto, Japan
E. Salehi
AUT, Tehran, Iran

Delbrück scattering is the elastic scattering of photons by the electromagnetic field of an atomic nucleus, as a consequence of vacuum polarization. The isolated measurement of Delbrück scattering has not been performed because of interference with other elastic scattering processes. It was recently discovered that, using linearly polarized photons, Delbrück scattering can be measured nearly independently of the other scattering processes*. In order to perform a proof of principle experiment, a quasi-monochromatic gamma-ray beam with a maximum photon energy of 1 MeV has been generated at the UVSOR facility by colliding a CO2 laser with a 750-MeV electron beam. A preliminary experiment has been performed with 0.5-W laser power and 1-mA electron beam current. As a result, the measured gamma-ray flux was evaluated as 0.0006 photon/eV/mA/W/s around the peak energy of 1 MeV. If we accept 20 percent energy spread, in case of a 100-W CO2 laser colliding with a 300 mA electron beam, approximately 4 x 10⁶-photons/s gamma-rays could be obtained. This flux is sufficiently high for the proof of principle experiment.
*J.K. Koga and T. Hayakawa, Phys. Rev. Lett. 118, 204801 (2017).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML049

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF074

Study of the Saturation of Radiation Energy Caused by the Space Charge Effect in a Compact THz Coherent Radiation Source

4245

SUSPF018

use link to see paper's listing under its alternate paper code

S. Krainara, Chatani, S. Chatani, T. Kii, H. Ohgaki, H. Zen
Kyoto University, Kyoto, Japan

Funding: Institute of Advanced Energy, Kyoto University
To generate an intense quasi-monochromatic Terahertz Coherent Undulator Radiation (THz-CUR), a compact linac system, which employs a magnetic electron bunch compressor with a beam energy of 4.6 MeV, has been constructed at Kyoto University. The THz-CUR has suc-cessfully been generated in a frequency range from 0.16 to 0.65 THz with a bunch charge of 60 pC. The maximum micro-pulse energy of THz radiation was observed higher than 1 μJ at 0.16 THz with 160 pC. However, when a bunch charge was higher than 80 pC, the micro-pulse energy of THz radiation gradually went to the saturation and obviously at the bunch charge higher than 110 pC because of the bunch lengthening and degradation of electron beam quality due to the space charge effect. The dependence of a bunch length on a bunch charge has been studied by GPT simulation and compared with CTR and CUR experiments. The trends of the measured results from CUR and CTR are in good agreement with the GPT simulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF074

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)