eeFACT2018 - List of Keywords (optics)

Paper	Title	Other Keywords	Page
MOXAA02	Highlights from SuperKEKB Commissioning	luminosity, MMI, coupling, detector	1
	Y. Ohnishi KEK, Ibaraki, Japan
	SuperKEKB is an electron-positron double-ring asymmetric-energy collider to search new physics phenomena appeared in B-boson decays. In order to accomplish this purpose, the huge statics, it is necessary for 40 times the luminosity as high as the predecessor KEKB collider. The strategy is that the vertical beta function at the IP is squeezed down to 1/20 and the beam currents doubles those of KEKB while keeping the same beam-beam parameter. The vertical beta function at the IP will be much smaller than the bunch length, however, the hourglass effect which degrades the luminosity will be reduced by adopting a novel ‘‘nano-beam’ scheme. First of all, the Phase 2 commissioning was focused on the verification of nano-beam scheme. Secondary, beam related background at the Belle II detector was also studied for the preparation of the pixel vertex detector installed before the Phase 3 operation. The preliminary results and accomplishments of the commissioning in Phase 2 will be reported in this article.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-MOXAA02
About •	paper received ※ 12 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
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TUOAB04	Optics Corrections including IP Local Coupling at SuperKEKB	coupling, luminosity, MMI, operation	63
	A. Morita, H. Koiso, K. Ohmi, Y. Ohnishi, H. Sugimoto, D. Zhou KEK, Ibaraki, Japan
	The phase-2 commissioning of the SuperKEKB accelerator with the interaction point(IP) has been performed from March 19 to July 17. In the collision operation during this commissioning, the vertical beta function at the IP was squeezed down to 3mm. In order to achieve such low beta collision operation, many optics corrections were performed. We present the result of those optics measurement and correction.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOAB04
About •	paper received ※ 12 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUOBB01	Optics Aberration at IP and Beam-beam Effects	luminosity, coupling, emittance, MMI	66
	K. Ohmi, Y. Funakoshi, H. Koiso, A. Morita, Y. Ohnishi, D. Zhou KEK, Ibaraki, Japan K. Hirosawa Sokendai, Ibaraki, Japan
	Collision in SuperKEKB phase II commissioning has started in April 2018. Luminosity was lower than the geomterical value even in very low bunch current. Linear x-y coupling at IP caused by skew of QCS was conjectured as error source. x-y coupling correction using skew corrector of QCS resulted in luminosity recover of 2 times. After the QCS skew correction, luminosity is still limited at relatively low bunch current. Nonlinear x-y coupling at IP is conjectured as a source of the luminosity limitation. We discuss effects of linear and nonlinear x-y coupling at IP on the beam-beam performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOBB01
About •	paper received ※ 25 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
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TUOBB02	Off-momentum Optics at SuperKEKB	sextupole, coupling, lattice, dynamic-aperture	71
	Y. Ohnishi, H. Koiso, A. Morita, K. Ohmi, H. Sugimoto KEK, Ibaraki, Japan K. Oide CERN, Meyrin, Switzerland
	The nano-beam scheme can squeeze the vertical beta function at the IP much smaller than the bunch length. It implies that the large chromaticity is generated in the vicinity of the final focus quadrupole magnets and the strong sextupoles are adopted to correct the chromaticity, for instance the local chromaticity corrections. While understanding of the off-momentum optics is important to optimize the dynamic aperture to make Touschek lifetime long and to reduce the luminosity degradation due to chromatic behaviors. In general, there is a discrepancy between measurements and those obtained from the optics model. The chromatic phase-advance is introduced to measure the off-momentum optics and correct by using sextupole magnets.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOBB02
About •	paper received ※ 12 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB06	Design and Beam Dynamics of the CEPC Booster	booster, injection, collider, emittance	146
	D. Wang, X. Cui, J. Gao, D. Ji, Y.D. Liu, C. Meng, N. Wang, C.H. Yu, J.Y. Zhai, Y. Zhang IHEP, Beijing, People’s Republic of China
	The CEPC booster needs to provide electron and positron beams to the collider at different energy with required injection speed. A 10 GeV linac is adopted as the injector for CDR. Then the beam energy is accelerated to specific energy according to three modes of CEPC collider ring (H, W and Z). The geometry of booster is designed carefully in order to share the same tunnel with collider. The design status of booster including parameters, optics and dynamic aperture is discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPAB06
About •	paper received ※ 26 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
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Paper

Title

Other Keywords

Page

MOXAA02

Highlights from SuperKEKB Commissioning

luminosity, MMI, coupling, detector

1

Y. Ohnishi
KEK, Ibaraki, Japan

SuperKEKB is an electron-positron double-ring asymmetric-energy collider to search new physics phenomena appeared in B-boson decays. In order to accomplish this purpose, the huge statics, it is necessary for 40 times the luminosity as high as the predecessor KEKB collider. The strategy is that the vertical beta function at the IP is squeezed down to 1/20 and the beam currents doubles those of KEKB while keeping the same beam-beam parameter. The vertical beta function at the IP will be much smaller than the bunch length, however, the hourglass effect which degrades the luminosity will be reduced by adopting a novel ‘‘nano-beam’ scheme. First of all, the Phase 2 commissioning was focused on the verification of nano-beam scheme. Secondary, beam related background at the Belle II detector was also studied for the preparation of the pixel vertex detector installed before the Phase 3 operation. The preliminary results and accomplishments of the commissioning in Phase 2 will be reported in this article.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-MOXAA02

About •

paper received ※ 12 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019

Export •

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

TUOAB04

Optics Corrections including IP Local Coupling at SuperKEKB

coupling, luminosity, MMI, operation

63

A. Morita, H. Koiso, K. Ohmi, Y. Ohnishi, H. Sugimoto, D. Zhou
KEK, Ibaraki, Japan

The phase-2 commissioning of the SuperKEKB accelerator with the interaction point(IP) has been performed from March 19 to July 17. In the collision operation during this commissioning, the vertical beta function at the IP was squeezed down to 3mm. In order to achieve such low beta collision operation, many optics corrections were performed. We present the result of those optics measurement and correction.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOAB04

About •

paper received ※ 12 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019

Export •

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

TUOBB01

Optics Aberration at IP and Beam-beam Effects

luminosity, coupling, emittance, MMI

66

K. Ohmi, Y. Funakoshi, H. Koiso, A. Morita, Y. Ohnishi, D. Zhou
KEK, Ibaraki, Japan
K. Hirosawa
Sokendai, Ibaraki, Japan

Collision in SuperKEKB phase II commissioning has started in April 2018. Luminosity was lower than the geomterical value even in very low bunch current. Linear x-y coupling at IP caused by skew of QCS was conjectured as error source. x-y coupling correction using skew corrector of QCS resulted in luminosity recover of 2 times. After the QCS skew correction, luminosity is still limited at relatively low bunch current. Nonlinear x-y coupling at IP is conjectured as a source of the luminosity limitation. We discuss effects of linear and nonlinear x-y coupling at IP on the beam-beam performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOBB01

About •

paper received ※ 25 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019

Export •

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

TUOBB02

Off-momentum Optics at SuperKEKB

sextupole, coupling, lattice, dynamic-aperture

71

Y. Ohnishi, H. Koiso, A. Morita, K. Ohmi, H. Sugimoto
KEK, Ibaraki, Japan
K. Oide
CERN, Meyrin, Switzerland

The nano-beam scheme can squeeze the vertical beta function at the IP much smaller than the bunch length. It implies that the large chromaticity is generated in the vicinity of the final focus quadrupole magnets and the strong sextupoles are adopted to correct the chromaticity, for instance the local chromaticity corrections. While understanding of the off-momentum optics is important to optimize the dynamic aperture to make Touschek lifetime long and to reduce the luminosity degradation due to chromatic behaviors. In general, there is a discrepancy between measurements and those obtained from the optics model. The chromatic phase-advance is introduced to measure the off-momentum optics and correct by using sextupole magnets.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOBB02

About •

paper received ※ 12 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019

Export •

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

TUPAB06

Design and Beam Dynamics of the CEPC Booster

booster, injection, collider, emittance

146

D. Wang, X. Cui, J. Gao, D. Ji, Y.D. Liu, C. Meng, N. Wang, C.H. Yu, J.Y. Zhai, Y. Zhang
IHEP, Beijing, People’s Republic of China

The CEPC booster needs to provide electron and positron beams to the collider at different energy with required injection speed. A 10 GeV linac is adopted as the injector for CDR. Then the beam energy is accelerated to specific energy according to three modes of CEPC collider ring (H, W and Z). The geometry of booster is designed carefully in order to share the same tunnel with collider. The design status of booster including parameters, optics and dynamic aperture is discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUPAB06

About •

paper received ※ 26 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019

Export •

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