IPAC2015 - List of Authors (Yamamoto, M.)

Paper	Title	Page
TUBC1	Recent Progress and Operational Status of the Compact ERL at KEK	1359
	S. Sakanaka, M. Adachi, S. Adachi, T. Akagi, M. Akemoto, D.A. Arakawa, S. Araki, S. Asaoka, M. Egi, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X.J. Jin, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, A. Kosuge, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sasaki, K. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, O. Tanaka, Y. Tanimoto, N. Terunuma, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, J. Urakawa, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan R. Hajima, S. Matsuba, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma JAEA, Ibaraki-ken, Japan J.G. Hwang KNU, Deagu, Republic of Korea M. Kuriki Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan Y. Seimiya HU/AdSM, Higashi-Hiroshima, Japan
	Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program from the MEXT, and by the MEXT grant for promoting technology for nuclear security. The Compact Energy Recovery Linac (cERL) is a superconducting test accelerator aimed at establishing technologies for the ERL-based future light source. After its construction during 2009 to 2013, the first CW beams of 20 MeV were successfully transported through the recirculation loop in February 2014. Then, initial tuning of beams and evaluations of beam properties were carried out. From September to December in 2014, we are constructing a Laser Compton Scattering (LCS) source* which aims at demonstrating technology for the future high-flux quasi-monochromatic gamma-ray source. In the next run of the cERL, which begins at the end of January 2015, we plan such works as an increase in the beam current (from 10 uA to 100 uA), commissioning of the LCS source, and sustained tuning of beams for lower emittance. We will report up-to-date results of these developments. * N. Nakamura et al., IPAC2014, MOPRO110; S. Sakanaka et al., LINAC14, TUPOL01. ** R. Nagai et al., IPAC2014, WEPRO003.
	Slides TUBC1 [2.679 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUBC1
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TUPWA067	Status of Higher Bunch Charge Operation in Compact ERL	1583
	T. Miyajima, K. Harada, Y. Honda, T. Miura, N. Nakamura, T. Obina, F. Qiu, H. Sakai, S. Sakanaka, M. Shimada, R. Takai, K. Umemori, M. Yamamoto KEK, Ibaraki, Japan R. Hajima, R. Nagai, N. Nishimori JAEA, Ibaraki-ken, Japan D. Lee KNU, Deagu, Republic of Korea
	In the KEK compact ERL (cERL), machine studies toward higher bunch charge operation is one of the most important issues. From January 2015 to April 2015, we carried out a higher bunch charge operation with an bunch charge of 0.5 pC for the experiment of laser compton scattering. After the study of space charge effect and optics tuning, we succeeded in the recirculation operation with the emittance, which was close to the design value. Moreover, a test operation in the injector section with the bunch charge of 7.7 pC was carried out as a preparation toward the recirculation operation with the average current of 10 mA.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA067
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WEAD3	Quantum Efficiency Improvement of Polarized Electron Source using Strain Compensated Super Lattice Photocathode	2479
	N. Yamamoto, M. Hosaka, A. Mano, T. Miyauchi, Y. Takashima, Y. Takeda Nagoya University, Nagoya, Japan X.J. Jin, M. Yamamoto KEK, Ibaraki, Japan
	Polarized electron beam is essential for future electron-positron colliders and electron-ion colliders. Improving the quantum efficiency is an important subject to realize those proposed applications. Recently we have developed the strain compensated superlattice (SL) photocathode. In the strain compensated SLs, the equivalent compressive and tensile strains introduced in the well and barrier SL layers so that strain relaxation is effectively suppressed with increasing the SL layer thickness and high crystal quality can be expected. In this study, we fabricated the GaAs/GaAsP strain compensated SLs with the thickness up to 90-pair SL layers. Up to now, the electron spin polarization of 92 % and the quantum efficiency of 1.6 % were simultaneously achieved from 24-pair sample. In the presentation, we show the effect of the superlattice thickness on the photocathode performances and discuss the photocathode physics.
	Slides WEAD3 [3.064 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEAD3
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WEPWA016	CsKSb Photocathode R&D with High Quantum Efficiency and Long Lifetime	2526
	Y. Seimiya, R. Kaku, M. Kuriki, A. Yokota HU/AdSM, Higashi-Hiroshima, Japan T. Konomi UVSOR, Okazaki, Japan T. Miyajima, M. Yamamoto KEK, Ibaraki, Japan
	Advanced electron linear accelerator such as Energy Recovery Linac and Free Electron Laser needs high brightness electron source. Photocathode is suitable for the high brightness requirement because some of them has low emittance and high quantum efficiency. In the photocathode, CsKSb multi-alkali photocathode has excellent features: high quantum efficiency, long lifetime, and driven by visible light, for example green laser. Therefore, the multi-alkali photocathode is considered to be one of the best candidates for the high brightness electron source of the advanced electron accelerator. We report developments of our evaporation system and results of quantum efficiency and lifetime measurement in Hiroshima University. Multi-alkali surface analyzation has being measured by ultra-violet photoemission spectroscopy to study conditions between the multi-alkali performances and the surface condition in Institute Molecular Science. We also report the status of the progress abort the study.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA016
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WEPMA060	The Development of Cavity Frequency Tracking Type RF Control System for SRF-TEM	2914
	N. Higashi The University of Tokyo, Graduate School of Science, Tokyo, Japan A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, M. Nishiwaki, H. Sakai, M. Sawabe, K. Ueno, M. Yamamoto KEK, Ibaraki, Japan M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan S. Yamashita ICEPP, Tokyo, Japan
	Superconducting accelerating cavities used in high-energy accelerators can generate high electric fields of several 10 MV/m by supplying radio frequency waves (RF) with frequencies matched with resonant frequencies of the cavities. Generally, frequencies of input RFs are fixed, and resonant frequencies of cavities that are fluctuated by Lorentz force detuning and Microphonics are corrected by feedbacks of cavity frequency tuners and input RF power. Now, we aim to develop the cavity frequency tracking type RF control system where the frequency of input RF is not fixed and consistently modulated to match the varying resonant frequency of the cavity. In KEK (Tsukuba, Japan), we are developing SRF-TEM that is a new type of transmission electron microscope using special-shaped superconducting cavity. By applying our new RF control system to the SRF-TEM, it is expected to obtain stable accelerating fields so that we can acquire good spatial resolution. In this presentation, we will explain the required stabilities of accelerating fields for SRF-TEM and the feasibility of SRF-TEM in the case of applying the cavity frequency tracking type RF control system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA060
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Paper

Title

Page

Recent Progress and Operational Status of the Compact ERL at KEK

1359

S. Sakanaka, M. Adachi, S. Adachi, T. Akagi, M. Akemoto, D.A. Arakawa, S. Araki, S. Asaoka, M. Egi, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X.J. Jin, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, A. Kosuge, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sasaki, K. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, O. Tanaka, Y. Tanimoto, N. Terunuma, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, J. Urakawa, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
R. Hajima, S. Matsuba, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma
JAEA, Ibaraki-ken, Japan
J.G. Hwang
KNU, Deagu, Republic of Korea
M. Kuriki
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
Y. Seimiya
HU/AdSM, Higashi-Hiroshima, Japan

Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program from the MEXT, and by the MEXT grant for promoting technology for nuclear security.
The Compact Energy Recovery Linac (cERL) is a superconducting test accelerator aimed at establishing technologies for the ERL-based future light source. After its construction during 2009 to 2013, the first CW beams of 20 MeV were successfully transported through the recirculation loop in February 2014*. Then, initial tuning of beams and evaluations of beam properties were carried out. From September to December in 2014, we are constructing a Laser Compton Scattering (LCS) source** which aims at demonstrating technology for the future high-flux quasi-monochromatic gamma-ray source. In the next run of the cERL, which begins at the end of January 2015, we plan such works as an increase in the beam current (from 10 uA to 100 uA), commissioning of the LCS source, and sustained tuning of beams for lower emittance. We will report up-to-date results of these developments.
* N. Nakamura et al., IPAC2014, MOPRO110; S. Sakanaka et al., LINAC14, TUPOL01.
** R. Nagai et al., IPAC2014, WEPRO003.

Slides TUBC1 [2.679 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUBC1

Export •

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

TUPWA067

Status of Higher Bunch Charge Operation in Compact ERL

1583

T. Miyajima, K. Harada, Y. Honda, T. Miura, N. Nakamura, T. Obina, F. Qiu, H. Sakai, S. Sakanaka, M. Shimada, R. Takai, K. Umemori, M. Yamamoto
KEK, Ibaraki, Japan
R. Hajima, R. Nagai, N. Nishimori
JAEA, Ibaraki-ken, Japan
D. Lee
KNU, Deagu, Republic of Korea

In the KEK compact ERL (cERL), machine studies toward higher bunch charge operation is one of the most important issues. From January 2015 to April 2015, we carried out a higher bunch charge operation with an bunch charge of 0.5 pC for the experiment of laser compton scattering. After the study of space charge effect and optics tuning, we succeeded in the recirculation operation with the emittance, which was close to the design value. Moreover, a test operation in the injector section with the bunch charge of 7.7 pC was carried out as a preparation toward the recirculation operation with the average current of 10 mA.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA067

Export •

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

WEAD3

Quantum Efficiency Improvement of Polarized Electron Source using Strain Compensated Super Lattice Photocathode

2479

N. Yamamoto, M. Hosaka, A. Mano, T. Miyauchi, Y. Takashima, Y. Takeda
Nagoya University, Nagoya, Japan
X.J. Jin, M. Yamamoto
KEK, Ibaraki, Japan

Polarized electron beam is essential for future electron-positron colliders and electron-ion colliders. Improving the quantum efficiency is an important subject to realize those proposed applications. Recently we have developed the strain compensated superlattice (SL) photocathode. In the strain compensated SLs, the equivalent compressive and tensile strains introduced in the well and barrier SL layers so that strain relaxation is effectively suppressed with increasing the SL layer thickness and high crystal quality can be expected. In this study, we fabricated the GaAs/GaAsP strain compensated SLs with the thickness up to 90-pair SL layers. Up to now, the electron spin polarization of 92 % and the quantum efficiency of 1.6 % were simultaneously achieved from 24-pair sample. In the presentation, we show the effect of the superlattice thickness on the photocathode performances and discuss the photocathode physics.

Slides WEAD3 [3.064 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEAD3

Export •

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

WEPWA016

CsKSb Photocathode R&D with High Quantum Efficiency and Long Lifetime

2526

Y. Seimiya, R. Kaku, M. Kuriki, A. Yokota
HU/AdSM, Higashi-Hiroshima, Japan
T. Konomi
UVSOR, Okazaki, Japan
T. Miyajima, M. Yamamoto
KEK, Ibaraki, Japan

Advanced electron linear accelerator such as Energy Recovery Linac and Free Electron Laser needs high brightness electron source. Photocathode is suitable for the high brightness requirement because some of them has low emittance and high quantum efficiency. In the photocathode, CsKSb multi-alkali photocathode has excellent features: high quantum efficiency, long lifetime, and driven by visible light, for example green laser. Therefore, the multi-alkali photocathode is considered to be one of the best candidates for the high brightness electron source of the advanced electron accelerator. We report developments of our evaporation system and results of quantum efficiency and lifetime measurement in Hiroshima University. Multi-alkali surface analyzation has being measured by ultra-violet photoemission spectroscopy to study conditions between the multi-alkali performances and the surface condition in Institute Molecular Science. We also report the status of the progress abort the study.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA016

Export •

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

WEPMA060

The Development of Cavity Frequency Tracking Type RF Control System for SRF-TEM

2914

N. Higashi
The University of Tokyo, Graduate School of Science, Tokyo, Japan
A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, M. Nishiwaki, H. Sakai, M. Sawabe, K. Ueno, M. Yamamoto
KEK, Ibaraki, Japan
M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
S. Yamashita
ICEPP, Tokyo, Japan

Superconducting accelerating cavities used in high-energy accelerators can generate high electric fields of several 10 MV/m by supplying radio frequency waves (RF) with frequencies matched with resonant frequencies of the cavities. Generally, frequencies of input RFs are fixed, and resonant frequencies of cavities that are fluctuated by Lorentz force detuning and Microphonics are corrected by feedbacks of cavity frequency tuners and input RF power. Now, we aim to develop the cavity frequency tracking type RF control system where the frequency of input RF is not fixed and consistently modulated to match the varying resonant frequency of the cavity. In KEK (Tsukuba, Japan), we are developing SRF-TEM that is a new type of transmission electron microscope using special-shaped superconducting cavity. By applying our new RF control system to the SRF-TEM, it is expected to obtain stable accelerating fields so that we can acquire good spatial resolution. In this presentation, we will explain the required stabilities of accelerating fields for SRF-TEM and the feasibility of SRF-TEM in the case of applying the cavity frequency tracking type RF control system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA060

Export •

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