IPAC2017 - List of Authors (Sakaue, K.)

Paper	Title	Page
MOPAB072	Measurement of Three-Dimensional Distribution of Electron Bunch Using RF Transverse Deflector	285
SUSPSIK074	use link to see paper's listing under its alternate paper code
	Y. Nakazato, Y. Koshiba, T. Sasaki, M. Washio Waseda University, Tokyo, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
	We have been studying a high quality electron beam generated by a photocathode RF gun at Waseda University. The electron beam is applied to a pulse radiolysis experiment, laser Compton scattering for soft X-ray generation, and a THz imaging experiment using coherent radiation. In these applications, longitudinal parameters of the electron beam are important. For this reason, we developed the RF deflector system which can directly convert longitudinal distribution of the beam to transverse with high temporal resolution, and performed longitudinal profile measurements of an electron beam from the RF gun. During a series of experiments using an RF deflector, we found that the bunch had a horizontal angle with respect to z axis. Thus we tried to reconstruct the three-dimensional profile of the bunch by computed tomography* in order to visualize the three-dimensional distribution of the bunch. In this conference, we will report the principle of measurement, experimental results of the bunch three-dimensional measurement, and future prospects. * J. Shi, et al., Reconstruction of the three-dimensional bunch profile by tomography technique with RF deflecting cavity, Nucl. Instrum. Methods Phys. Res., A 752 (2014) 36-41
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB072
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MOPVA023	Luminosity Increase in Laser-Compton Scattering by Crab Crossing Method	902
	Y. Koshiba, D. Igarashi, S. Ota, T. Takahashi, M. Washio RISE, Tokyo, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan J. Urakawa KEK, Ibaraki, Japan
	In collider experiments such as KEKB, crab crossing method is a promising way to increase the luminosity. We are planning to apply crab crossing to laser-Compton scattering, which is a collision of electron beam and laser, to gain a higher luminosity leading to a higher flux X-ray source. It is well known that the collision angle between electron beam and laser affects the luminosity. It is the best when the collision angle is zero, head-on collision, to get a higher luminosity but difficult to construct such system especially when using an optical cavity for laser. Concerning this difficulty, we are planning crab crossing by tilting the electron beam using an rf-deflector. Although crab crossing in laser-Compton scattering has been already proposed, nowhere has demonstrated yet. We are going to demonstrate and conduct experimental study at our compact accelerator system in Waseda University. In this conference, we will report about our compact accelerator system, laser system for laser-Compton scattering, and expected results of crab crossing laser-Compton scattering. Variola Alessandro, et al. Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators. Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA023
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MOPVA024	Investigation of the Coherent Cherenkov Radiation Using Tilted Electron Bunch	905
	K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M. Brameld, M. Nishida, T. Toida, M. Washio, R. Yanagisawa Waseda University, Tokyo, Japan R. Kuroda, Y. Taira AIST, Tsukuba, Ibaraki, Japan J. Urakawa KEK, Ibaraki, Japan
	Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083. Cherenkov radiation can be produced when the velocity of the charged particles are faster than the light in some medium. We investigated the coherent Cherenkov radiation using electron bunch tilting for matching the wave front of the Cherenkov radiation. The electron bunch was tilted by using rf transverse deflecting cavity. We tested several materials for the Cherenkov target which has enough transmittance at the wavelength of THz region. As a result, high peak power THz was achieved using this novel technique. We will report the principle of this technique, the experimental results and future prospects at the conference.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA024
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TUPAB059	Study on CsKSb Photocathode for the RF Electron Gun	1456
SUSPSIK022	use link to see paper's listing under its alternate paper code
	H. Ono, J. Miyamatsu, M. Washio Waseda University, Tokyo, Japan H. Iijima Tokyo University of Science, Tokyo, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
	At Waseda University, we have been developing a Cs-Te photocathode S-band RF electron gun and application experiments of the electron beam. On the experiments, charge amount is important factor, which strongly depends on laser power and photocathode quality. At present, we are studying CsKSb photocathode to increase the charge amount of an electron beam generated from the RF-Gun. As a result of using CsKSb photocathode in the RF-cavity, we obtained as much charge as using Cs-Te photocathode but the lifetime was shorter than that of Cs-Te. In order to lengthen the photocathode lifetime, we tried to coat a protective film on CsKSb photocathode surface and investigated its robustness for poor vacuum condition that simulates cathode transportation and usage in the RF-Gun. In this conference, we report current status of fabricating coated photocathode and future prospects. A. Buzulutskov et al. The protection of K-Cs-Sb photocathodes with CsBr films Nuclear Instruments and Methods in Physics Research A 400 (1997) 173-176
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB059
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TUPAB060	Development of the Laser System for the Proof-of-Principle Experiment of Crab Crossing Laser-Compton Scattering	1460
	T. Takahashi, D. Igarashi, Y. Koshiba, S. Ota, M. Washio RISE, Tokyo, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan J. Urakawa KEK, Ibaraki, Japan
	An X-ray source via laser-Compton scattering has the advantage of small source, energy tunability and quasi-monochromaticity and is expected to be applied in a wide range of fields such as the industry and medical care. In laser-Compton scattering, the luminosity, which represents the collision frequency between the electrons and the photons, is very important. Increasing the luminosity is strongly required for increasing the scattered photon flux. One way to increase the luminosity is tilting electron bunches at the collision point, which is called crab crossing. It is the way to create the head-on collision artificially. The purpose of this study is the proof-of-principle of the crab crossing laser-Compton scattering. In this conference, we will report the design optimization and construction of the laser system for the collision and future prospects. Variola Alessandro, et al. Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators. Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB060
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THPAB119	Study on a Time-Domain Spectroscopy System for Coherent Terahertz Pulse Spectrum Measurement from 5 MeV Electron Beam	4003
	R. Yanagisawa, T. Toida Waseda University, Tokyo, Japan K. Kan ISIR, Osaka, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M. Washio RISE, Tokyo, Japan
	Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083. Terahertz wave, expected to apply spectral analysis and imaging, has recently developed both source and detector components. For the terahertz source, the coherent radiation from electron linac is expected to be the high power terahertz source. At Waseda University, we have been studying high quality electron beam generation using Cs-Te photocathode RF-Gun and its application. We tried to generate terahertz wave by the coherent radiation and to measure its spectrum by a time-domain spectroscopy (TDS) technique. Adopting this technique, ultra-short laser pulse is needed as probe light. A terahertz waveform appears by delaying the timing of probe pulse. A spectrum of terahertz wave is also led by the waveform, by using the Fourier transform. We succeeded in constructing the probe laser system operating at 119 MHz repetition rate. The pulse duration was compressed down to 190 fs (FWHM) by using pulse compressor. We also succeeded in measuring a terahertz radiation from a photoconductive antenna. In this conference, we will report the outline of our terahertz TDS system, recent progress of our laser system, and terahertz wave generation and detection, with the future prospects.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB119
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

MOPAB072

Measurement of Three-Dimensional Distribution of Electron Bunch Using RF Transverse Deflector

285

SUSPSIK074

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

Y. Nakazato, Y. Koshiba, T. Sasaki, M. Washio
Waseda University, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan

We have been studying a high quality electron beam generated by a photocathode RF gun at Waseda University. The electron beam is applied to a pulse radiolysis experiment, laser Compton scattering for soft X-ray generation, and a THz imaging experiment using coherent radiation. In these applications, longitudinal parameters of the electron beam are important. For this reason, we developed the RF deflector system which can directly convert longitudinal distribution of the beam to transverse with high temporal resolution, and performed longitudinal profile measurements of an electron beam from the RF gun. During a series of experiments using an RF deflector, we found that the bunch had a horizontal angle with respect to z axis. Thus we tried to reconstruct the three-dimensional profile of the bunch by computed tomography* in order to visualize the three-dimensional distribution of the bunch. In this conference, we will report the principle of measurement, experimental results of the bunch three-dimensional measurement, and future prospects.
* J. Shi, et al., Reconstruction of the three-dimensional bunch profile by tomography technique with RF deflecting cavity, Nucl. Instrum. Methods Phys. Res., A 752 (2014) 36-41

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB072

Export •

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

MOPVA023

Luminosity Increase in Laser-Compton Scattering by Crab Crossing Method

902

Y. Koshiba, D. Igarashi, S. Ota, T. Takahashi, M. Washio
RISE, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

In collider experiments such as KEKB, crab crossing method is a promising way to increase the luminosity. We are planning to apply crab crossing to laser-Compton scattering, which is a collision of electron beam and laser, to gain a higher luminosity leading to a higher flux X-ray source. It is well known that the collision angle between electron beam and laser affects the luminosity. It is the best when the collision angle is zero, head-on collision, to get a higher luminosity but difficult to construct such system especially when using an optical cavity for laser. Concerning this difficulty, we are planning crab crossing by tilting the electron beam using an rf-deflector. Although crab crossing in laser-Compton scattering has been already proposed*, nowhere has demonstrated yet. We are going to demonstrate and conduct experimental study at our compact accelerator system in Waseda University. In this conference, we will report about our compact accelerator system, laser system for laser-Compton scattering, and expected results of crab crossing laser-Compton scattering.
*Variola Alessandro, et al. Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators. Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA023

Export •

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

MOPVA024

Investigation of the Coherent Cherenkov Radiation Using Tilted Electron Bunch

905

K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Brameld, M. Nishida, T. Toida, M. Washio, R. Yanagisawa
Waseda University, Tokyo, Japan
R. Kuroda, Y. Taira
AIST, Tsukuba, Ibaraki, Japan
J. Urakawa
KEK, Ibaraki, Japan

Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083.
Cherenkov radiation can be produced when the velocity of the charged particles are faster than the light in some medium. We investigated the coherent Cherenkov radiation using electron bunch tilting for matching the wave front of the Cherenkov radiation. The electron bunch was tilted by using rf transverse deflecting cavity. We tested several materials for the Cherenkov target which has enough transmittance at the wavelength of THz region. As a result, high peak power THz was achieved using this novel technique. We will report the principle of this technique, the experimental results and future prospects at the conference.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA024

Export •

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

TUPAB059

Study on CsKSb Photocathode for the RF Electron Gun

1456

SUSPSIK022

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

H. Ono, J. Miyamatsu, M. Washio
Waseda University, Tokyo, Japan
H. Iijima
Tokyo University of Science, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan

At Waseda University, we have been developing a Cs-Te photocathode S-band RF electron gun and application experiments of the electron beam. On the experiments, charge amount is important factor, which strongly depends on laser power and photocathode quality. At present, we are studying CsKSb photocathode to increase the charge amount of an electron beam generated from the RF-Gun. As a result of using CsKSb photocathode in the RF-cavity, we obtained as much charge as using Cs-Te photocathode but the lifetime was shorter than that of Cs-Te. In order to lengthen the photocathode lifetime, we tried to coat a protective film on CsKSb photocathode surface and investigated its robustness for poor vacuum condition that simulates cathode transportation and usage in the RF-Gun. In this conference, we report current status of fabricating coated photocathode and future prospects.
A. Buzulutskov et al. The protection of K-Cs-Sb photocathodes with CsBr films Nuclear Instruments and Methods in Physics Research A 400 (1997) 173-176

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB059

Export •

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

TUPAB060

Development of the Laser System for the Proof-of-Principle Experiment of Crab Crossing Laser-Compton Scattering

1460

T. Takahashi, D. Igarashi, Y. Koshiba, S. Ota, M. Washio
RISE, Tokyo, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

An X-ray source via laser-Compton scattering has the advantage of small source, energy tunability and quasi-monochromaticity and is expected to be applied in a wide range of fields such as the industry and medical care. In laser-Compton scattering, the luminosity, which represents the collision frequency between the electrons and the photons, is very important. Increasing the luminosity is strongly required for increasing the scattered photon flux. One way to increase the luminosity is tilting electron bunches at the collision point, which is called crab crossing. It is the way to create the head-on collision artificially. The purpose of this study is the proof-of-principle of the crab crossing laser-Compton scattering. In this conference, we will report the design optimization and construction of the laser system for the collision and future prospects.
Variola Alessandro, et al. Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators. Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB060

Export •

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

THPAB119

Study on a Time-Domain Spectroscopy System for Coherent Terahertz Pulse Spectrum Measurement from 5 MeV Electron Beam

4003

R. Yanagisawa, T. Toida
Waseda University, Tokyo, Japan
K. Kan
ISIR, Osaka, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
RISE, Tokyo, Japan

Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083.
Terahertz wave, expected to apply spectral analysis and imaging, has recently developed both source and detector components. For the terahertz source, the coherent radiation from electron linac is expected to be the high power terahertz source. At Waseda University, we have been studying high quality electron beam generation using Cs-Te photocathode RF-Gun and its application. We tried to generate terahertz wave by the coherent radiation and to measure its spectrum by a time-domain spectroscopy (TDS) technique. Adopting this technique, ultra-short laser pulse is needed as probe light. A terahertz waveform appears by delaying the timing of probe pulse. A spectrum of terahertz wave is also led by the waveform, by using the Fourier transform. We succeeded in constructing the probe laser system operating at 119 MHz repetition rate. The pulse duration was compressed down to 190 fs (FWHM) by using pulse compressor. We also succeeded in measuring a terahertz radiation from a photoconductive antenna. In this conference, we will report the outline of our terahertz TDS system, recent progress of our laser system, and terahertz wave generation and detection, with the future prospects.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB119

Export •

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