IPAC2011 - List of Authors (Ohnishi, Y.)

Paper	Title	Page
WEPO027	Design Study of Final Focusing Superconducting Magnets for the SuperKEKB	2457
	M. Tawada, N. Higashi, M. Iwasaki, H. Koiso, A. Morita, Y. Ohnishi, N. Ohuchi, K. Oide, T. Oki, K. Tsuchiya, H. Yamaoka, Z.G. Zong KEK, Ibaraki, Japan
	For SuperKEKB, which is an upgrade project of KEKB, we are studying the design of the final focus quadrupole magnets for the interaction region. The 7 GeV electrons in the high-energy ring and the 4 GeV positrons in the low-energy ring collide at one IP with a finite crossing angle of 83 mrad. For each beam, the final beam focusing system consists of the superconducting quadrupole-doublets. These quadrupole magnets have to meet specifications described below. (1) Because of the small beam separation between two beam lines, the superconducting magnet is designed with thin coils and the conductor size is required to be minimized. (2) Since the beta functions are so large, a large space with a good field quality is required. (3) These magnets must apply the focusing fields on electrons and positrons, independent each other. The quadrupole magnets in the solenoid field of the particle detector are designed without an iron yoke. Consequently, the reduction of the leakage fields from the adjacent beam lines is a critical issue to achieve large dynamic aperture. In this paper we will report the design of final focusing system.

THPZ006	SuperKEKB Interaction Region Modeling	3690
	A. Morita, H. Koiso, Y. Ohnishi, K. Oide, Y. Sugimoto KEK, Ibaraki, Japan
	In the SuperKEKB interaction region(IR) design, the beam-line intersects solenoid-axis with large angle and the superconducting final focusing quadrupole magnets are installed into each beam-lines without iron-shield. Because of these features, the emittance and dynamic aperture evaluation have to consider the solenoid fringe field and the leakage multipole field of another beam-line magnet, respectively. The IR lattice modeling and the magnetic field handling of both solenoid and multipole field would be reported in this article.

THPZ007	Lattice Design of Low Emittance and Low Beta Function at Collision Point for SuperKEKB	3693
	Y. Ohnishi, H. Koiso, A. Morita, K. Oide, H. Sugimoto KEK, Ibaraki, Japan
	Extremely low beta function at the interaction point(IP) and low emittance are necessary to achieve the design luminosity of 8x10³5 cm^-2 s^-1 for a SuperKEKB project. The low emittance with a large Piwinski angle makes this possible with longer bunch longitudinally compared with the vertical beta function at IP. We call this Nano-beam scheme. In this scheme, a beam-beam parameter is realized to be less than 0.09 for the design luminosity. The lattice features, chromaticity corrections, and dynamic aperture are discussed in this article.

THPZ009	Beam Background Simulation for SuperKEKB/Belle-II	3699
	H. Nakano, H. Yamamoto Tohoku University, Graduate School of Science, Sendai, Japan K. Kanazawa, H. Nakayama, Y. Ohnishi KEK, Ibaraki, Japan C. Kiesling, S. Koblitz, A. Moll, M. Ritter MPI-P, München, Germany
	The Belle experiment is now being upgraded to the Belle II experiment designed for a 40 times higher luminosity. Such a high luminosity is realized by the SuperKEKB collider where beam-induced background rates are expected to be much higher than those of KEKB. This poses a serious challenge for the design of the machine-detector interface. We have thus carried out a GEANT4-based beam background simulation for Touschek effect. We describe the method of generating background particles and present the result of simulation.

THPZ010	Beam Background and MDI Design for SuperKEKB/Belle-II	3702
	H. Nakayama, M. Iwasaki, K. Kanazawa, Y. Ohnishi, S. Tanaka, T. Tsuboyama KEK, Ibaraki, Japan H. Nakano Tohoku University, Graduate School of Science, Sendai, Japan
	The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 at^-1before the shutdown in June 2010. We have started upgrading both the accelerator and detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8x10³5 cm^-2s^-1. With the increased luminosity, the beam background will also increase. The development of Machine-Detector Interface (MDI) design is very important to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB and our countermeasures for them, such as collimators to stop Touschek-scattered beam particles, Tungsten shield to protect inner detectors from shower particles, dedicated beam pipe design around interaction point to stop synchrotron radiation, etc.

Paper

Title

Page

Design Study of Final Focusing Superconducting Magnets for the SuperKEKB

2457

M. Tawada, N. Higashi, M. Iwasaki, H. Koiso, A. Morita, Y. Ohnishi, N. Ohuchi, K. Oide, T. Oki, K. Tsuchiya, H. Yamaoka, Z.G. Zong
KEK, Ibaraki, Japan

For SuperKEKB, which is an upgrade project of KEKB, we are studying the design of the final focus quadrupole magnets for the interaction region. The 7 GeV electrons in the high-energy ring and the 4 GeV positrons in the low-energy ring collide at one IP with a finite crossing angle of 83 mrad. For each beam, the final beam focusing system consists of the superconducting quadrupole-doublets. These quadrupole magnets have to meet specifications described below. (1) Because of the small beam separation between two beam lines, the superconducting magnet is designed with thin coils and the conductor size is required to be minimized. (2) Since the beta functions are so large, a large space with a good field quality is required. (3) These magnets must apply the focusing fields on electrons and positrons, independent each other. The quadrupole magnets in the solenoid field of the particle detector are designed without an iron yoke. Consequently, the reduction of the leakage fields from the adjacent beam lines is a critical issue to achieve large dynamic aperture. In this paper we will report the design of final focusing system.

THPZ006

SuperKEKB Interaction Region Modeling

3690

A. Morita, H. Koiso, Y. Ohnishi, K. Oide, Y. Sugimoto
KEK, Ibaraki, Japan

In the SuperKEKB interaction region(IR) design, the beam-line intersects solenoid-axis with large angle and the superconducting final focusing quadrupole magnets are installed into each beam-lines without iron-shield. Because of these features, the emittance and dynamic aperture evaluation have to consider the solenoid fringe field and the leakage multipole field of another beam-line magnet, respectively. The IR lattice modeling and the magnetic field handling of both solenoid and multipole field would be reported in this article.

THPZ007

Lattice Design of Low Emittance and Low Beta Function at Collision Point for SuperKEKB

3693

Y. Ohnishi, H. Koiso, A. Morita, K. Oide, H. Sugimoto
KEK, Ibaraki, Japan

Extremely low beta function at the interaction point(IP) and low emittance are necessary to achieve the design luminosity of 8x10³5 cm^-2 s^-1 for a SuperKEKB project. The low emittance with a large Piwinski angle makes this possible with longer bunch longitudinally compared with the vertical beta function at IP. We call this Nano-beam scheme. In this scheme, a beam-beam parameter is realized to be less than 0.09 for the design luminosity. The lattice features, chromaticity corrections, and dynamic aperture are discussed in this article.

THPZ009

Beam Background Simulation for SuperKEKB/Belle-II

3699

H. Nakano, H. Yamamoto
Tohoku University, Graduate School of Science, Sendai, Japan
K. Kanazawa, H. Nakayama, Y. Ohnishi
KEK, Ibaraki, Japan
C. Kiesling, S. Koblitz, A. Moll, M. Ritter
MPI-P, München, Germany

The Belle experiment is now being upgraded to the Belle II experiment designed for a 40 times higher luminosity. Such a high luminosity is realized by the SuperKEKB collider where beam-induced background rates are expected to be much higher than those of KEKB. This poses a serious challenge for the design of the machine-detector interface. We have thus carried out a GEANT4-based beam background simulation for Touschek effect. We describe the method of generating background particles and present the result of simulation.

THPZ010

Beam Background and MDI Design for SuperKEKB/Belle-II

3702

H. Nakayama, M. Iwasaki, K. Kanazawa, Y. Ohnishi, S. Tanaka, T. Tsuboyama
KEK, Ibaraki, Japan
H. Nakano
Tohoku University, Graduate School of Science, Sendai, Japan

The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 at^-1before the shutdown in June 2010. We have started upgrading both the accelerator and detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8x10³5 cm^-2s^-1. With the increased luminosity, the beam background will also increase. The development of Machine-Detector Interface (MDI) design is very important to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB and our countermeasures for them, such as collimators to stop Touschek-scattered beam particles, Tungsten shield to protect inner detectors from shower particles, dedicated beam pipe design around interaction point to stop synchrotron radiation, etc.