IPAC2017 - List of Authors (Ogawa, Y.)

Paper	Title	Page
TUPAB004	Progress of 7-GeV SuperKEKB Injector Linac Upgrade and Commissioning	1300
	K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, H. Ego, A. Enomoto, Y. Enomoto, S. Fukuda, Y. Funahashi, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kawamura, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, M. Nishida, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, D. Satoh, M. Satoh, Y. Seimiya, A. Shirakawa, H. Sugimoto, H. Sugimura, T. Suwada, T. Takatomi, T. Takenaka, M. Tanaka, N. Toge, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou KEK, Ibaraki, Japan
	KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It is being upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of new physics beyond the standard model of elementary particle physics. SuperKEKB asymmetric electron and positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. Electron beams will be generated by a new type of RF gun, that will provide a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 micron to 20 micron in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The recent status of the upgrade and beam commissioning is reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB004
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TUPAB056	New Achievements of the Laser System for RF-Gun at SuperKEKB Injector	1452
	R. Zhang, T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou KEK, Ibaraki, Japan
	For realizing high charge and low emittance electron and positron beams in SuperKEKB, we have been making improvements in current laser system for RF-gun. In order to realize more excellent thermal management in current laser system at high repetition rate operation, novel soldering Yb:YAG thin disk and copper tungsten heat sink laser head is manufactured via gold tin solder. Comparing with old design, less residual stress is introduced and more efficient thermal removal can be obtained. These new soldering laser heads are placed into a compact vacuum chamber and cooled by Peltier plates directly. This design can realize higher gain and amplification factor in regenerative amplifier and multi-pass amplifier. In addition, the compact and simple cooling method can achieve excellent thermal management for the purpose of realize laser operation at high repetition rate for following phases of SuperKEKB project. A perspective towards the next step experiment is also presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB056
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WEPAB044	Construction and Commissioning of Direct Beam Transport Line for PF-AR	2678
	N. Higashi, S. Asaoka, K. Furukawa, K. Haga, K. Harada, T. Higo, T. Honda, H. Honma, N. Iida, H. Iwase, K. Kakihara, T. Kamitani, M. Kikuchi, Y. Kishimoto, Y. Kobayashi, K. Kodama, K. Kudo, T. Kume, K. Mikawa, T. Mimashi, F. Miyahara, H. Miyauchi, S. Nagahashi, H. Nakamura, N. Nakamura, T. Natsui, K.N. Nigorikawa, Y. Niwa, T. Nogami, T. Obina, Y. Ogawa, M. Ono, T. Ozaki, H. Sagehashi, T. Sanami, M. Sato, M. Satoh, T. Suwada, M. Tadano, T. Tahara, R. Takai, H. Takaki, S. Takasaki, M. Tanaka, Y. Tanimoto, M. Tawada, N. Toge, T. Uchiyama, A. Ueda, Y. Yamada, M. Yamamoto, M. Yoshida KEK, Ibaraki, Japan
	PF-AR was constructed as an accumulator ring for TRISTAN, and in the KEKB era it has been revitalized as a 6.5 GeV synchrotron radiation source. The injection energy was 3 GeV and the beam was accelerated to 6.5 GeV prior to the user run. The original beam transport line (BT) from the LINAC to the PF-AR shared its upstream part with the the BT line of KEKB High Energy Ring (HER). The injection-mode change from PF-AR to HER or vice versa needs about 10 minutes for the magnet cycling procedure of the shared part. In SuperKEKB, the upgrade of KEKB, the lifetime of HER is about 10 minutes. The mode-switch operation of the BT is, therefore, not allowed for maintaining the highest luminosity of the SuperKEKB. In order to avoid this problem, a new 6.5 GeV BT line dedicated to PF-AR has been constructed. This also enables the top-up injection for the user run. The commissioning of the new BT line has been completed in this March, and now the first user run has been operated successfully.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB044
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THPVA047	Developing an Yb/Nd Doped Hybrid Solid Laser of RF Gun for SuperKEKB Phase II Commissioning	4540
	X. Zhou, T. Natsui, Y. Ogawa, M. Yoshida, R. Zhang KEK, Ibaraki, Japan
	The electron beams with a charge of several nC and a normalized emittance of less than 10 'm are expected to be generated in the photocathode RF gun for injector linac of SuperKEKB accelerator project. By development of the Yb-doped laser system, more than 1.0 nC electron has been obtained in 25 Hz. The laser system is already for commissioning phase I. But, the 30 ps pulse width stretch limit the pulse energy of the amplifier laser system. As well-established laser material, Nd:YAG rods with high optical homogeneity and high damage threshold, simplify the design of high-pulse-energy amplifier. Therefore, a new Nd/Yb hybrid laser system is development to increase the pulse energy of the laser source. For phase II commissioning, more than 3 nC electron beam is expected. Also, a chirped pulse amplification (CPA) laser system is prepared for the phase III commissioning, both pulse energy and pulse shaping controller are expected.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA047
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Paper

Title

Page

Progress of 7-GeV SuperKEKB Injector Linac Upgrade and Commissioning

1300

K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, H. Ego, A. Enomoto, Y. Enomoto, S. Fukuda, Y. Funahashi, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kawamura, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, M. Nishida, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, D. Satoh, M. Satoh, Y. Seimiya, A. Shirakawa, H. Sugimoto, H. Sugimura, T. Suwada, T. Takatomi, T. Takenaka, M. Tanaka, N. Toge, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
KEK, Ibaraki, Japan

KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It is being upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of new physics beyond the standard model of elementary particle physics. SuperKEKB asymmetric electron and positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. Electron beams will be generated by a new type of RF gun, that will provide a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 micron to 20 micron in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The recent status of the upgrade and beam commissioning is reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB004

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TUPAB056

New Achievements of the Laser System for RF-Gun at SuperKEKB Injector

1452

R. Zhang, T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
KEK, Ibaraki, Japan

For realizing high charge and low emittance electron and positron beams in SuperKEKB, we have been making improvements in current laser system for RF-gun. In order to realize more excellent thermal management in current laser system at high repetition rate operation, novel soldering Yb:YAG thin disk and copper tungsten heat sink laser head is manufactured via gold tin solder. Comparing with old design, less residual stress is introduced and more efficient thermal removal can be obtained. These new soldering laser heads are placed into a compact vacuum chamber and cooled by Peltier plates directly. This design can realize higher gain and amplification factor in regenerative amplifier and multi-pass amplifier. In addition, the compact and simple cooling method can achieve excellent thermal management for the purpose of realize laser operation at high repetition rate for following phases of SuperKEKB project. A perspective towards the next step experiment is also presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB056

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WEPAB044

Construction and Commissioning of Direct Beam Transport Line for PF-AR

2678

N. Higashi, S. Asaoka, K. Furukawa, K. Haga, K. Harada, T. Higo, T. Honda, H. Honma, N. Iida, H. Iwase, K. Kakihara, T. Kamitani, M. Kikuchi, Y. Kishimoto, Y. Kobayashi, K. Kodama, K. Kudo, T. Kume, K. Mikawa, T. Mimashi, F. Miyahara, H. Miyauchi, S. Nagahashi, H. Nakamura, N. Nakamura, T. Natsui, K.N. Nigorikawa, Y. Niwa, T. Nogami, T. Obina, Y. Ogawa, M. Ono, T. Ozaki, H. Sagehashi, T. Sanami, M. Sato, M. Satoh, T. Suwada, M. Tadano, T. Tahara, R. Takai, H. Takaki, S. Takasaki, M. Tanaka, Y. Tanimoto, M. Tawada, N. Toge, T. Uchiyama, A. Ueda, Y. Yamada, M. Yamamoto, M. Yoshida
KEK, Ibaraki, Japan

PF-AR was constructed as an accumulator ring for TRISTAN, and in the KEKB era it has been revitalized as a 6.5 GeV synchrotron radiation source. The injection energy was 3 GeV and the beam was accelerated to 6.5 GeV prior to the user run. The original beam transport line (BT) from the LINAC to the PF-AR shared its upstream part with the the BT line of KEKB High Energy Ring (HER). The injection-mode change from PF-AR to HER or vice versa needs about 10 minutes for the magnet cycling procedure of the shared part. In SuperKEKB, the upgrade of KEKB, the lifetime of HER is about 10 minutes. The mode-switch operation of the BT is, therefore, not allowed for maintaining the highest luminosity of the SuperKEKB. In order to avoid this problem, a new 6.5 GeV BT line dedicated to PF-AR has been constructed. This also enables the top-up injection for the user run. The commissioning of the new BT line has been completed in this March, and now the first user run has been operated successfully.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB044

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THPVA047

Developing an Yb/Nd Doped Hybrid Solid Laser of RF Gun for SuperKEKB Phase II Commissioning

4540

X. Zhou, T. Natsui, Y. Ogawa, M. Yoshida, R. Zhang
KEK, Ibaraki, Japan

The electron beams with a charge of several nC and a normalized emittance of less than 10 'm are expected to be generated in the photocathode RF gun for injector linac of SuperKEKB accelerator project. By development of the Yb-doped laser system, more than 1.0 nC electron has been obtained in 25 Hz. The laser system is already for commissioning phase I. But, the 30 ps pulse width stretch limit the pulse energy of the amplifier laser system. As well-established laser material, Nd:YAG rods with high optical homogeneity and high damage threshold, simplify the design of high-pulse-energy amplifier. Therefore, a new Nd/Yb hybrid laser system is development to increase the pulse energy of the laser source. For phase II commissioning, more than 3 nC electron beam is expected. Also, a chirped pulse amplification (CPA) laser system is prepared for the phase III commissioning, both pulse energy and pulse shaping controller are expected.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA047

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