IPAC2016 - List of Authors (Ohmi, K.)

Paper	Title	Page
MOZA01	Simulated Beam-beam Limits for Circular Lepton and Hadron Colliders	27
	K. Ohmi KEK, Ibaraki, Japan
	The beam-beam limit is one of the most important collider parameters. For lepton colliders the empirical tune shift limits are higher than for hadron colliders, which has been attributed to strong radiation damping. The beam-beam limit in hadron colliders, like the LHC, can be affected by noise. For future higher-energy colliders, like FCC-hh or SppC, the limit can be higher or lower, in the presence of still rather weak synchrotron radiation. For circular lepton colliders, like DAΦNE, SuperKEKB, FCC-ee or CepC, the effect of large Piwinski angle, and crab waist, as well as the dependence of the beam-beam limit on the number of interaction points are important questions. This presentation reviews the state of the art in weak-strong, quasi-strong-strong and strong-strong beam-beam simulations and reports the various dependencies of the simulated beam-beam limit on the aforementioned parameters.
	Slides MOZA01 [4.453 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOZA01
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MOPOR019	Beta Function Measurement and Resonances Induced by Space Charge Force and Lattice Magnets	641
	K. Ohmi, K.G. Sonnad KEK, Ibaraki, Japan
	J-PARC MR has been operated at tune (ν_x,ν_y)=(22.40,20.75). A new operating point around (21.4,21.4) has been proposed by simulation studies on space charge effect since 2013. Machine experiments at the operating point has been performed since 2014 and many encouraging results are being obtained. We discuss why new operating point is better than present one from view point of space charge effects.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR019
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TUOBA01	Beam Commissioning of SuperKEKB	1019
	Y. Funakoshi, T. Abe, T. Adachi, K. Akai, Y. Arimoto, K. Egawa, Y. Enomoto, J.W. Flanagan, H. Fukuma, K. Furukawa, N. Iida, H. Iinuma, H. Ikeda, T. Ishibashi, M. Iwasaki, T. Kageyama, H. Kaji, T. Kamitani, T. Kawamoto, S. Kazama, M. Kikuchi, T. Kobayashi, K. Kodama, H. Koiso, M. Masuzawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, S. Nakamura, T.T. Nakamura, H. Nakayama, T. Natsui, M. Nishiwaki, K. Ohmi, Y. Ohnishi, T. Oki, S. Sasaki, M. Satoh, Y. Seimiya, K. Shibata, M. Suetake, Y. Suetsugu, H. Sugimoto, M. Tanaka, M. Tawada, S. Terui, M. Tobiyama, S. Uehara, S. Uno, X. Wang, K. Watanabe, Y. Yano, S.I. Yoshimoto, R. Zhang, D. Zhou, X. Zhou, Z.G. Zong KEK, Ibaraki, Japan D. El Khechen LAL, Orsay, France
	In this report, we describe the machine operation in the first 3 months of the Phase 1 commissioning of SuperKEKB. The beam commissioning is smoothly going on. Vacuum scrubbing, the optics corrections and others are described.
	Slides TUOBA01 [9.346 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOBA01
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TUPOW006	Six-dimensional Phase-space Rotation and its Applications	1754
	M. Kuriki, K. Negishi HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, R. Kato, K. Ohmi, M. Satoh, Y. Seimiya, J. Urakawa KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Funding: This work is partly supported by Grant-in-Aid for Scientific Research by MEXT, Japan (KAKENHI) 25390126. Recent progress on the accelerator science requires optimized phase space distributions of the beam for each applications. A classical approach to satisfy the requirements is minimizing the beam emittance with a bunch charge as much as possible. This classical approach is not efficient and not compatible to the beam dynamics nature. 6D phase-space rotation, e.g. z-x and x-y, gives a way to optimize the phase space distribution for various applications. In this article, we discus possible applications of the 6D phase space rotation. The x-y rotation generates the high aspect ratio beam for linear colliders directly without DR (Damping Ring). Combination of bunch clipping with a mechanical slit and x-z rotation can generate micro-bunch structure which is applicable for FEL enhancement and drive beam for dielectric acceleration. We present our theoretical and simulation study on these applications.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW006
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WEPOY004	Integrated Green Function for Charged Particle moving along Bending Orbit	2997
	K. Ohmi, S. Chen KEK, Ibaraki, Japan H. Tanaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	Electro-magnetic field for moving charged particle is given by Liennard-Wiechert potential. The field contains high frequency component corresponding to synchrotron light, ω=3cγ³/(2ρ). The frequency is too high to study beam behavior generally. Green function integrated over beam distribution and/or over in a region σ_x/n_x× σ_y/n_y× σ_z/n_z (n_xyz ∼ 10) is useful to study instability and emittance growth of the beam. The green function is regarded as the wake field for coherent synchrotron radiation in three dimension space.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY004
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THPOR007	Optics Measurements and Corrections at the Early Commissioning of SuperKEKB	3782
	Y. Ohnishi, Y. Funakoshi, H. Koiso, A. Morita, K. Ohmi, K. Oide, H. Sugimoto, D. Zhou KEK, Ibaraki, Japan M.E. Biagini, M. Boscolo, S. Guiducci INFN/LNF, Frascati (Roma), Italy N. Carmignani, S.M. Liuzzo ESRF, Grenoble, France
	We present experimental results of measurements and corrections of the optics at the early Phase-1 commissioning of SuperKEKB which is a positron-electron collider built to achieve the target luminosity of 8x10³⁵ cm^-2s^-1. We have three stages; the Phase-1 is the commissioning of the machine without the final focus magnets and detector solenoid(no collision); the collision with the final focus system and the Belle II detector will be performed at the Phase-2 and Phase-3. The strategy for the luminosity upgrade is a novel "nano-beam'' scheme found elsewhere. In order to achieve the target luminosity, the vertical emittance has to be reduced by corrections of machine error measured by orbit responses. The vertical emittance should be achieved to be less than 6 pm(0.2 % coupling) during the Phase-1 by fully utilizing correction tools of skew quadrupole-like coils wound on sextupole magnets and power supplies for each correction coil in quadrupole magnets. In addition to the linear optics, the optics for off-momentum particles is also studied to understand a dynamic aperture affects the Touschek lifetime. "SuperB Conceptual Design Report", INFN/AE-07/2, SLAV-R-856, LAL 07-15, (2007).
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR007
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THPOR022	Design of Beam Optics for the FCC-ee Collider Ring	3821
	K. Oide, K. Ohmi, D. Zhou KEK, Ibaraki, Japan M. Aiba PSI, Villigen PSI, Switzerland S. Aumon, M. Benedikt, H. Burkhardt, A. Doblhammer, B. Härer, B.J. Holzer, J.M. Jowett, M. Koratzinos, L.E. Medina Medrano, Y. Papaphilippou, J. Wenninger, F. Zimmermann CERN, Geneva, Switzerland A.P. Blondel DPNC, Genève, Switzerland A.V. Bogomyagkov, I. Koop, E.B. Levichev, P.A. Piminov, D.N. Shatilov, D.B. Shwartz, S.V. Sinyatkin BINP SB RAS, Novosibirsk, Russia M. Boscolo INFN/LNF, Frascati (Roma), Italy Y. Cai, M.K. Sullivan, U. Wienands SLAC, Menlo Park, California, USA
	A design of beam optics will be presented for the FCC-ee double-ring collider. The main characteristics are 45 to 175 GeV beam energy, 100 km circumference with two IPs/ring, 30 mrad crossing angle at the IP, crab-waist scheme with local chromaticity correction system, and "tapering" of the magnets along with the local beam energy. An asymmetric layout near the interaction region suppresses the critical energy of synchrotron radiation toward the detector at the IP less than 100 keV, while keeping the geometry as close as to the FCC-hh beam line. A sufficient transverse/longitudinal dynamic aperture is obtained to assure the lifetime with beamstrahlung and top-up injection. The synchrotron radiation in all magnets, the IP solenoid and its compensation, nonlinearity of the final quadrupoles are taken into account.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR022
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Paper

Title

Page

Simulated Beam-beam Limits for Circular Lepton and Hadron Colliders

27

K. Ohmi
KEK, Ibaraki, Japan

The beam-beam limit is one of the most important collider parameters. For lepton colliders the empirical tune shift limits are higher than for hadron colliders, which has been attributed to strong radiation damping. The beam-beam limit in hadron colliders, like the LHC, can be affected by noise. For future higher-energy colliders, like FCC-hh or SppC, the limit can be higher or lower, in the presence of still rather weak synchrotron radiation. For circular lepton colliders, like DAΦNE, SuperKEKB, FCC-ee or CepC, the effect of large Piwinski angle, and crab waist, as well as the dependence of the beam-beam limit on the number of interaction points are important questions. This presentation reviews the state of the art in weak-strong, quasi-strong-strong and strong-strong beam-beam simulations and reports the various dependencies of the simulated beam-beam limit on the aforementioned parameters.

Slides MOZA01 [4.453 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOZA01

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

MOPOR019

Beta Function Measurement and Resonances Induced by Space Charge Force and Lattice Magnets

641

K. Ohmi, K.G. Sonnad
KEK, Ibaraki, Japan

J-PARC MR has been operated at tune (ν_x,ν_y)=(22.40,20.75). A new operating point around (21.4,21.4) has been proposed by simulation studies on space charge effect since 2013. Machine experiments at the operating point has been performed since 2014 and many encouraging results are being obtained. We discuss why new operating point is better than present one from view point of space charge effects.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR019

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TUOBA01

Beam Commissioning of SuperKEKB

1019

Y. Funakoshi, T. Abe, T. Adachi, K. Akai, Y. Arimoto, K. Egawa, Y. Enomoto, J.W. Flanagan, H. Fukuma, K. Furukawa, N. Iida, H. Iinuma, H. Ikeda, T. Ishibashi, M. Iwasaki, T. Kageyama, H. Kaji, T. Kamitani, T. Kawamoto, S. Kazama, M. Kikuchi, T. Kobayashi, K. Kodama, H. Koiso, M. Masuzawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, S. Nakamura, T.T. Nakamura, H. Nakayama, T. Natsui, M. Nishiwaki, K. Ohmi, Y. Ohnishi, T. Oki, S. Sasaki, M. Satoh, Y. Seimiya, K. Shibata, M. Suetake, Y. Suetsugu, H. Sugimoto, M. Tanaka, M. Tawada, S. Terui, M. Tobiyama, S. Uehara, S. Uno, X. Wang, K. Watanabe, Y. Yano, S.I. Yoshimoto, R. Zhang, D. Zhou, X. Zhou, Z.G. Zong
KEK, Ibaraki, Japan
D. El Khechen
LAL, Orsay, France

In this report, we describe the machine operation in the first 3 months of the Phase 1 commissioning of SuperKEKB. The beam commissioning is smoothly going on. Vacuum scrubbing, the optics corrections and others are described.

Slides TUOBA01 [9.346 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOBA01

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TUPOW006

Six-dimensional Phase-space Rotation and its Applications

1754

M. Kuriki, K. Negishi
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, R. Kato, K. Ohmi, M. Satoh, Y. Seimiya, J. Urakawa
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Funding: This work is partly supported by Grant-in-Aid for Scientific Research by MEXT, Japan (KAKENHI) 25390126.
Recent progress on the accelerator science requires optimized phase space distributions of the beam for each applications. A classical approach to satisfy the requirements is minimizing the beam emittance with a bunch charge as much as possible. This classical approach is not efficient and not compatible to the beam dynamics nature. 6D phase-space rotation, e.g. z-x and x-y, gives a way to optimize the phase space distribution for various applications. In this article, we discus possible applications of the 6D phase space rotation. The x-y rotation generates the high aspect ratio beam for linear colliders directly without DR (Damping Ring). Combination of bunch clipping with a mechanical slit and x-z rotation can generate micro-bunch structure which is applicable for FEL enhancement and drive beam for dielectric acceleration. We present our theoretical and simulation study on these applications.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW006

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WEPOY004

Integrated Green Function for Charged Particle moving along Bending Orbit

2997

K. Ohmi, S. Chen
KEK, Ibaraki, Japan
H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

Electro-magnetic field for moving charged particle is given by Liennard-Wiechert potential. The field contains high frequency component corresponding to synchrotron light, ω=3cγ³/(2ρ). The frequency is too high to study beam behavior generally. Green function integrated over beam distribution and/or over in a region σ_x/n_x× σ_y/n_y× σ_z/n_z (n_xyz ∼ 10) is useful to study instability and emittance growth of the beam. The green function is regarded as the wake field for coherent synchrotron radiation in three dimension space.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY004

Export •

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

THPOR007

Optics Measurements and Corrections at the Early Commissioning of SuperKEKB

3782

Y. Ohnishi, Y. Funakoshi, H. Koiso, A. Morita, K. Ohmi, K. Oide, H. Sugimoto, D. Zhou
KEK, Ibaraki, Japan
M.E. Biagini, M. Boscolo, S. Guiducci
INFN/LNF, Frascati (Roma), Italy
N. Carmignani, S.M. Liuzzo
ESRF, Grenoble, France

We present experimental results of measurements and corrections of the optics at the early Phase-1 commissioning of SuperKEKB which is a positron-electron collider built to achieve the target luminosity of 8x10³⁵ cm^-2s^-1. We have three stages; the Phase-1 is the commissioning of the machine without the final focus magnets and detector solenoid(no collision); the collision with the final focus system and the Belle II detector will be performed at the Phase-2 and Phase-3. The strategy for the luminosity upgrade is a novel "nano-beam'' scheme found elsewhere*. In order to achieve the target luminosity, the vertical emittance has to be reduced by corrections of machine error measured by orbit responses. The vertical emittance should be achieved to be less than 6 pm(0.2 % coupling) during the Phase-1 by fully utilizing correction tools of skew quadrupole-like coils wound on sextupole magnets and power supplies for each correction coil in quadrupole magnets. In addition to the linear optics, the optics for off-momentum particles is also studied to understand a dynamic aperture affects the Touschek lifetime.
* "SuperB Conceptual Design Report", INFN/AE-07/2, SLAV-R-856, LAL 07-15, (2007).

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR007

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THPOR022

Design of Beam Optics for the FCC-ee Collider Ring

3821

K. Oide, K. Ohmi, D. Zhou
KEK, Ibaraki, Japan
M. Aiba
PSI, Villigen PSI, Switzerland
S. Aumon, M. Benedikt, H. Burkhardt, A. Doblhammer, B. Härer, B.J. Holzer, J.M. Jowett, M. Koratzinos, L.E. Medina Medrano, Y. Papaphilippou, J. Wenninger, F. Zimmermann
CERN, Geneva, Switzerland
A.P. Blondel
DPNC, Genève, Switzerland
A.V. Bogomyagkov, I. Koop, E.B. Levichev, P.A. Piminov, D.N. Shatilov, D.B. Shwartz, S.V. Sinyatkin
BINP SB RAS, Novosibirsk, Russia
M. Boscolo
INFN/LNF, Frascati (Roma), Italy
Y. Cai, M.K. Sullivan, U. Wienands
SLAC, Menlo Park, California, USA

A design of beam optics will be presented for the FCC-ee double-ring collider. The main characteristics are 45 to 175 GeV beam energy, 100 km circumference with two IPs/ring, 30 mrad crossing angle at the IP, crab-waist scheme with local chromaticity correction system, and "tapering" of the magnets along with the local beam energy. An asymmetric layout near the interaction region suppresses the critical energy of synchrotron radiation toward the detector at the IP less than 100 keV, while keeping the geometry as close as to the FCC-hh beam line. A sufficient transverse/longitudinal dynamic aperture is obtained to assure the lifetime with beamstrahlung and top-up injection. The synchrotron radiation in all magnets, the IP solenoid and its compensation, nonlinearity of the final quadrupoles are taken into account.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR022

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