IPAC2016 - List of Authors (Yamamoto, N.)

Paper	Title	Page
TUPOW036	Recent Developments and Operational Status of the Compact ERL at KEK	1835
	T. Obina, 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, R. Kato, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondo, T. Konomi, 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. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sakanaka, S. Sasaki, K. Satoh, Y. Seimiya, 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, N. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida KEK, Ibaraki, Japan R. Hajima, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma QST, Tokai, Japan M. Kuriki Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	The Compact Energy Recovery Linac (cERL) at KEK is a test accelerator in order to develop key components to realize remarkable ERL performance as a future light source. After the beam commissioning in December 2013, the legal current limit has been increased step-by-step like 1 uA, 10 uA, and 100 uA. Survey for the source of beam losses has been conducted in each step, and the study on beam dynamics and tuning has also been carried out. As a next step, 1 mA operation is scheduled in February 2016. In parallel to the increase in beam current, a laser Compton scattering (LCS) system which can provide high-flux X-ray to a beamline has been successfully commissioned. We report recent progress in various kinds of beam tuning: improvement of electron gun performance, high bunch charge operation, mitigation of beam losses, LCS optics tuning and bunch compression for THz radiation.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW036
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WEOAA03	Experimental Study on Optical Vortex from a Helical Undulator at UVSOR-III	2036
	M. Hosaka Nagoya University, Nagoya, Japan M. Katoh, N.S. Mirian UVSOR, Okazaki, Japan T. Konomi, N. Yamamoto KEK, Ibaraki, Japan K. Kuroda ISSP, Kashiwa-shi, Japan K. Miyamoto, S. Sasaki HSRC, Higashi-Hiroshima, Japan
	A relativistic electron in helical undulator emits an optical vortex which carries orbital angular momentum. Sasaki and McNulty predicted theoretically that higher harmonics of helical undulator is optical vortex* and the experimental verification was made at BESSY and UVSOR-III. Further, we have made a systematic study to characterize the optical vortex from a helical undulator at UVSOR-III. Synchrotron radiation in UV region from an optical klystron undulator system consisting of two APPLE-II helical undulators and a buncher was used for the experiment. Patterns resulting from inferences between two undulator radiation carrying different angular momentums were clearly observed. To investigate the optical properties of the radiation, diffraction experiments were carried out. Specific diffraction patterns due to the phase singularity in the radiation center were clearly observed. The experimental results are compared with simulation. S. Sasaki, I. McNulty, Phys. Rev. Lett. 100, 124801 (2008) J. Bahrdt et al., Phys. Rev. Lett. 111, 034801 (2013) * e.g. S. Sasaki et al., presented in SRI2015 (2015)
	Slides WEOAA03 [11.023 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAA03
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WEPMY039	Time Response Measurements for Transmission-Type GaAs/GaAsP Superlattice Photocathodes	2641
	N. Yamamoto, X.J. Jin KEK, Ibaraki, Japan M. Hosaka, Y. Takashima, K. Yamaguchi Nagoya University, Nagoya, Japan M. Katoh UVSOR, Okazaki, Japan
	Polarized electron beam is essential for future electron-positron colliders and electron-ion colliders. 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 this study, to compare the time response performances with the SL thicknesses, the measurements were carried out for conventional and strain compensated SL PCs. We show the measurement results and discuss the physics.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY039
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WEPOW020	Present Status of KEK Photon Factory and Future Project	2871
	T. Honda, M. Adachi, S. Asaoka, K. Haga, K. Harada, Y. Honda, X.J. Jin, T. Kageyama, R. Kato, Y. Kobayashi, K. Marutsuka, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, K.N. Nigorikawa, T. Nogami, T. Obina, M. Ono, T. Ozaki, H. Sagehashi, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, M. Shimada, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, O. Tanaka, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, N. Yamamoto, Ma. Yoshida, S.I. Yoshimoto KEK, Ibaraki, Japan
	Two synchrotron radiation sources of KEK, the PF-ring and the PF-AR, continue their user operation with various improvements. Scrap and build of the first generation undulators of 1980s at the PF-ring is pushed forward year by year. Five new elliptically polarized undulators have been installed in these five years, and we have also installed four very narrow-gap short-period undulators generating high brilliant X-ray. The new beam transport line that enables the 6.5-GeV full energy injection for PF-AR will be completed by the end of 2016 in order to make the top-up operation of the two SR sources compatible with the continuous injection for two main rings of the Super-KEKB. We have proposed a project of further upgrade of the 2.5-GeV PF-ring to improve its horizontal emittance as 8 nm rad using combined bending magnets at the arc sections. And we are also moving ahead on proposal of constructing a new KEK light source of an extremely low emittance as 0.3 nm rad. The progress and detail of our future project will be described in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW020
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WEPOW023	Present Status of Accelerators in Aichi Synchrotron Radiation Center	2877
	Y. Takashima, M. Hosaka, A. Mano Nagoya University, Nagoya, Japan Y. Hori, N. Yamamoto KEK, Ibaraki, Japan M. Katoh UVSOR, Okazaki, Japan S. Koda SAGA, Tosu, Japan S. Sasaki JASRI/SPring-8, Hyogo, Japan T. Takano Hitachi Ltd., Ibaraki-ken, Japan
	Aichi Synchrotron Radiation Center is the newest synchrotron radiation facility in Japan. The construction was started in 2010 and the facility was opened for public use on March 26, 2013. The circumference of the storage ring is 72 m with the electron energy of 1.2 GeV, the beam current of 300 mA and the natural emittance of about 53 nmrad. The beam is injected from a booster synchrotron with the energy of 1.2 GeV as full energy injection and the top-up operation has been carried out routinely with stored current of 300 mA since opened for public use. We have tested a pulsed multi-pole magnet for improving the deviation of the orbit of stored beam during the top-up beam injection. The storage ring consists of four triple bend cells. Eight of the twelve bending magnets are normal conducting ones. Four of them are 5 T superconducting magnets(superbend) of which bending angle is 12 degrees. The superbends are running without any trouble with refrigerator maintenance once per year. The accelerators have been operated about 1400 hours stable in a year. Eight of the synchrotron radiation beamlines have been operational for public use and other two beamlines are under construction.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW023
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THPOW005	A Study of CsK2Sb Multi-alkali Photocathode by Ultraviolet Photoelectron Spectroscopy at UVSOR	3934
SUPSS022	use link to see paper's listing under its alternate paper code
	M. Urano, M. Kuriki, K. Negishi HU/AdSM, Higashi-Hiroshima, Japan T. Konomi, Y. Seimiya, N. Yamamoto KEK, Ibaraki, Japan
	Photocathode is one of the most important components in the next-generation accelerators, especially based on linear accelerators. Photocathode performance depends not only on electronic state in its bulk material but also on the surface condition. CsK2Sb multi-alkali photocathode is a candidate for the high brightness electron source because of its high quantum efficiency by green laser and its high robustness. We have carried out an UPS (UV Photoelectron Spectroscopy) experiment at UVSOR facility, synchrotron radiation light source in Aichi Japan. We have compared the UPS spectra among several samples, each one has a different quantum efficiency, and try to find physics which decide photocathode's performance. In this case, we focused some characters correlated to the quantum efficiency. I'm going to present a result of this analysis.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW005
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Paper

Title

Page

Recent Developments and Operational Status of the Compact ERL at KEK

1835

T. Obina, 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, R. Kato, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondo, T. Konomi, 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. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sakanaka, S. Sasaki, K. Satoh, Y. Seimiya, 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, N. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
KEK, Ibaraki, Japan
R. Hajima, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma
QST, Tokai, Japan
M. Kuriki
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

The Compact Energy Recovery Linac (cERL) at KEK is a test accelerator in order to develop key components to realize remarkable ERL performance as a future light source. After the beam commissioning in December 2013, the legal current limit has been increased step-by-step like 1 uA, 10 uA, and 100 uA. Survey for the source of beam losses has been conducted in each step, and the study on beam dynamics and tuning has also been carried out. As a next step, 1 mA operation is scheduled in February 2016. In parallel to the increase in beam current, a laser Compton scattering (LCS) system which can provide high-flux X-ray to a beamline has been successfully commissioned. We report recent progress in various kinds of beam tuning: improvement of electron gun performance, high bunch charge operation, mitigation of beam losses, LCS optics tuning and bunch compression for THz radiation.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW036

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WEOAA03

Experimental Study on Optical Vortex from a Helical Undulator at UVSOR-III

2036

M. Hosaka
Nagoya University, Nagoya, Japan
M. Katoh, N.S. Mirian
UVSOR, Okazaki, Japan
T. Konomi, N. Yamamoto
KEK, Ibaraki, Japan
K. Kuroda
ISSP, Kashiwa-shi, Japan
K. Miyamoto, S. Sasaki
HSRC, Higashi-Hiroshima, Japan

A relativistic electron in helical undulator emits an optical vortex which carries orbital angular momentum. Sasaki and McNulty predicted theoretically that higher harmonics of helical undulator is optical vortex* and the experimental verification was made at BESSY** and UVSOR-III***. Further, we have made a systematic study to characterize the optical vortex from a helical undulator at UVSOR-III. Synchrotron radiation in UV region from an optical klystron undulator system consisting of two APPLE-II helical undulators and a buncher was used for the experiment. Patterns resulting from inferences between two undulator radiation carrying different angular momentums were clearly observed. To investigate the optical properties of the radiation, diffraction experiments were carried out. Specific diffraction patterns due to the phase singularity in the radiation center were clearly observed. The experimental results are compared with simulation.
* S. Sasaki, I. McNulty, Phys. Rev. Lett. 100, 124801 (2008)
** J. Bahrdt et al., Phys. Rev. Lett. 111, 034801 (2013)
*** e.g. S. Sasaki et al., presented in SRI2015 (2015)

Slides WEOAA03 [11.023 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAA03

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WEPMY039

Time Response Measurements for Transmission-Type GaAs/GaAsP Superlattice Photocathodes

2641

N. Yamamoto, X.J. Jin
KEK, Ibaraki, Japan
M. Hosaka, Y. Takashima, K. Yamaguchi
Nagoya University, Nagoya, Japan
M. Katoh
UVSOR, Okazaki, Japan

Polarized electron beam is essential for future electron-positron colliders and electron-ion colliders. 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 this study, to compare the time response performances with the SL thicknesses, the measurements were carried out for conventional and strain compensated SL PCs. We show the measurement results and discuss the physics.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY039

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WEPOW020

Present Status of KEK Photon Factory and Future Project

2871

T. Honda, M. Adachi, S. Asaoka, K. Haga, K. Harada, Y. Honda, X.J. Jin, T. Kageyama, R. Kato, Y. Kobayashi, K. Marutsuka, T. Miyajima, H. Miyauchi, S. Nagahashi, N. Nakamura, K.N. Nigorikawa, T. Nogami, T. Obina, M. Ono, T. Ozaki, H. Sagehashi, H. Sakai, S. Sakanaka, H. Sasaki, Y. Sato, M. Shimada, T. Shioya, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, O. Tanaka, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, N. Yamamoto, Ma. Yoshida, S.I. Yoshimoto
KEK, Ibaraki, Japan

Two synchrotron radiation sources of KEK, the PF-ring and the PF-AR, continue their user operation with various improvements. Scrap and build of the first generation undulators of 1980s at the PF-ring is pushed forward year by year. Five new elliptically polarized undulators have been installed in these five years, and we have also installed four very narrow-gap short-period undulators generating high brilliant X-ray. The new beam transport line that enables the 6.5-GeV full energy injection for PF-AR will be completed by the end of 2016 in order to make the top-up operation of the two SR sources compatible with the continuous injection for two main rings of the Super-KEKB. We have proposed a project of further upgrade of the 2.5-GeV PF-ring to improve its horizontal emittance as 8 nm rad using combined bending magnets at the arc sections. And we are also moving ahead on proposal of constructing a new KEK light source of an extremely low emittance as 0.3 nm rad. The progress and detail of our future project will be described in this paper.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW020

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WEPOW023

Present Status of Accelerators in Aichi Synchrotron Radiation Center

2877

Y. Takashima, M. Hosaka, A. Mano
Nagoya University, Nagoya, Japan
Y. Hori, N. Yamamoto
KEK, Ibaraki, Japan
M. Katoh
UVSOR, Okazaki, Japan
S. Koda
SAGA, Tosu, Japan
S. Sasaki
JASRI/SPring-8, Hyogo, Japan
T. Takano
Hitachi Ltd., Ibaraki-ken, Japan

Aichi Synchrotron Radiation Center is the newest synchrotron radiation facility in Japan. The construction was started in 2010 and the facility was opened for public use on March 26, 2013. The circumference of the storage ring is 72 m with the electron energy of 1.2 GeV, the beam current of 300 mA and the natural emittance of about 53 nmrad. The beam is injected from a booster synchrotron with the energy of 1.2 GeV as full energy injection and the top-up operation has been carried out routinely with stored current of 300 mA since opened for public use. We have tested a pulsed multi-pole magnet for improving the deviation of the orbit of stored beam during the top-up beam injection. The storage ring consists of four triple bend cells. Eight of the twelve bending magnets are normal conducting ones. Four of them are 5 T superconducting magnets(superbend) of which bending angle is 12 degrees. The superbends are running without any trouble with refrigerator maintenance once per year. The accelerators have been operated about 1400 hours stable in a year. Eight of the synchrotron radiation beamlines have been operational for public use and other two beamlines are under construction.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW023

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THPOW005

A Study of CsK2Sb Multi-alkali Photocathode by Ultraviolet Photoelectron Spectroscopy at UVSOR

3934

SUPSS022

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

M. Urano, M. Kuriki, K. Negishi
HU/AdSM, Higashi-Hiroshima, Japan
T. Konomi, Y. Seimiya, N. Yamamoto
KEK, Ibaraki, Japan

Photocathode is one of the most important components in the next-generation accelerators, especially based on linear accelerators. Photocathode performance depends not only on electronic state in its bulk material but also on the surface condition. CsK2Sb multi-alkali photocathode is a candidate for the high brightness electron source because of its high quantum efficiency by green laser and its high robustness. We have carried out an UPS (UV Photoelectron Spectroscopy) experiment at UVSOR facility, synchrotron radiation light source in Aichi Japan. We have compared the UPS spectra among several samples, each one has a different quantum efficiency, and try to find physics which decide photocathode's performance. In this case, we focused some characters correlated to the quantum efficiency. I'm going to present a result of this analysis.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW005

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