eeFACT2018 - Classification: Optics+dynamics

Paper	Title	Page
TUOAB01	Dynamic Aperture Limitation Due to the Synchrotron Radiation from Quadrupole Magnets in very High Energy Colliders	46
	A.V. Bogomyagkov, S.A. Glukhov, E.B. Levichev, S.V. Sinyatkin BINP SB RAS, Novosibirsk, Russia
	In a lepton storage ring of very high energy (e.g. in the e⁺e^- Higgs factory) synchrotron radiation from quadrupoles constraints transverse dynamic aperture even in the absence of any magnetic nonlinearities. This was observed in LEP and the Future Circular e⁺e^- Collider (FCC-ee). Synchrotron radiation in the quadrupoles modulates the particle energy at the double betatron frequency. Energy modulation varies transverse focusing strength at the same frequency and creates a parametric resonance of the betatron oscillations. Starting from 6d equations of motion we derive and solve the relevant differential equation describing the resonance, and show good agreement between analytical results and numerical simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOAB01
About •	paper received ※ 11 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
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TUOAB02	Low-emittance Tuning for Circular Colliders	57
	T.K. Charles The University of Melbourne, Melbourne, Victoria, Australia S. Aumon, B.J. Holzer, K. Oide, T. Tydecks, F. Zimmermann CERN, Geneva, Switzerland K. Oide KEK, Ibaraki, Japan
	The 100 km FCC-ee e⁺/e⁻ circular collider requires luminosities in the order of 10³⁵ cm^-2 s^-1 and very low emittances of 0.27 nm·prad for the horizontal plane and 1 pm·prad in the vertical. In order to reach these requirements, extreme focusing of the beam is needed in the interaction regions, leading to a vertical beta function of 0.8 mm at the IP. These challenges make the FCC-ee design particularly susceptible to misalignment and field errors. This paper describes the tolerance of the machine to magnet alignment errors and the effectiveness of optics and orbit correction methods that were implemented in order to bring the vertical dispersion to acceptable values, which in turn limits the vertical emittance. Thousands of misalignment and error seeds were introduced in MADX simulations and a comprehensive correction strategy, which includes macros based upon Dispersion Free Steering (DFS), linear coupling correction based on Resonant Driving Terms (RDTs) and response matrices, was implemented. The results are summarized in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOAB02
About •	paper received ※ 11 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019
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TUOBB01	Optics Aberration at IP and Beam-beam Effects	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	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
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TUOBB04	Different Optics within Large Energy Region at BEPCII	79
	C.H. Yu, Y. Bai, C.C. Du, Z. Duan, Y.Y. Guo, D. Ji, S.C. Jiang, Y. Jiao, Y.M. Peng, Q. Qin, Y.S. Sun, S.K. Tian, J.Q. Wang, N. Wang, X. Wang, Y. Wei, Wen. Wen, J. Wu, Xing. Xing, Xu. Xu, C. Zhang, Y. Zhang IHEP, Beijing, People’s Republic of China
	BEPCII is designed at the beam energy of 1.89 GeV. According to the requirements of high energy physics, BEPCII has been operated in the energy region from 1.0 GeV to 2.3 GeV since 2009. The energy region is quite large so that it is very important to select optics for the optimized luminosity. Different optics within different energy region at BEPCII will be introduced in detail in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOBB04
About •	paper received ※ 23 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)

Paper

Title

Page

Dynamic Aperture Limitation Due to the Synchrotron Radiation from Quadrupole Magnets in very High Energy Colliders

46

A.V. Bogomyagkov, S.A. Glukhov, E.B. Levichev, S.V. Sinyatkin
BINP SB RAS, Novosibirsk, Russia

In a lepton storage ring of very high energy (e.g. in the e⁺e^- Higgs factory) synchrotron radiation from quadrupoles constraints transverse dynamic aperture even in the absence of any magnetic nonlinearities. This was observed in LEP and the Future Circular e⁺e^- Collider (FCC-ee). Synchrotron radiation in the quadrupoles modulates the particle energy at the double betatron frequency. Energy modulation varies transverse focusing strength at the same frequency and creates a parametric resonance of the betatron oscillations. Starting from 6d equations of motion we derive and solve the relevant differential equation describing the resonance, and show good agreement between analytical results and numerical simulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOAB01

About •

paper received ※ 11 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)

TUOAB02

Low-emittance Tuning for Circular Colliders

57

T.K. Charles
The University of Melbourne, Melbourne, Victoria, Australia
S. Aumon, B.J. Holzer, K. Oide, T. Tydecks, F. Zimmermann
CERN, Geneva, Switzerland
K. Oide
KEK, Ibaraki, Japan

The 100 km FCC-ee e⁺/e⁻ circular collider requires luminosities in the order of 10³⁵ cm^-2 s^-1 and very low emittances of 0.27 nm·prad for the horizontal plane and 1 pm·prad in the vertical. In order to reach these requirements, extreme focusing of the beam is needed in the interaction regions, leading to a vertical beta function of 0.8 mm at the IP. These challenges make the FCC-ee design particularly susceptible to misalignment and field errors. This paper describes the tolerance of the machine to magnet alignment errors and the effectiveness of optics and orbit correction methods that were implemented in order to bring the vertical dispersion to acceptable values, which in turn limits the vertical emittance. Thousands of misalignment and error seeds were introduced in MADX simulations and a comprehensive correction strategy, which includes macros based upon Dispersion Free Steering (DFS), linear coupling correction based on Resonant Driving Terms (RDTs) and response matrices, was implemented. The results are summarized in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOAB02

About •

paper received ※ 11 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

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

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)

TUOBB04

Different Optics within Large Energy Region at BEPCII

79

C.H. Yu, Y. Bai, C.C. Du, Z. Duan, Y.Y. Guo, D. Ji, S.C. Jiang, Y. Jiao, Y.M. Peng, Q. Qin, Y.S. Sun, S.K. Tian, J.Q. Wang, N. Wang, X. Wang, Y. Wei, Wen. Wen, J. Wu, Xing. Xing, Xu. Xu, C. Zhang, Y. Zhang
IHEP, Beijing, People’s Republic of China

BEPCII is designed at the beam energy of 1.89 GeV. According to the requirements of high energy physics, BEPCII has been operated in the energy region from 1.0 GeV to 2.3 GeV since 2009. The energy region is quite large so that it is very important to select optics for the optimized luminosity. Different optics within different energy region at BEPCII will be introduced in detail in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOBB04

About •

paper received ※ 23 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)