eeFACT2018 - Table of Session: TUOBB (WG3 - Optics and Beam Dynamics)

Paper	Title	Page
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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TUOBB03	Progress of Preliminary Work for the Accelerators of a 2-7GeV Super Tau Charm Facility at China	76
	Q. Luo USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Funding: Work supported by National Natural Science Foundation of China U1832169 and the Fundamental Research Funds for the Central Univer-sities, Grant No WK2310000046 As the most successful tau-charm factory of the world, BEPC II will celebrate its 10th birthday this year and will finish its historical mission in the next decade. Because of its very important role in high energy phys-ics study, BEPC II will certainly need a successor, a new tau-charm collider. This paper discusses the feasi-bility of a greenfield next generation tau-charm collid-er named HIEPA. The luminosity of this successor is about 5×10³⁴ cm−2s−1 pilot and 1×1035cm^-2s⁻¹ nominal, with the electron beam longitudinally polarized at the IP. The general scheme of the accelerators and the beam parameters are shown. Several key technologies such as beam polarization and beam emittance diag-nostics are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOBB03
About •	paper received ※ 16 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
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Paper

Title

Page

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)

TUOBB03

Progress of Preliminary Work for the Accelerators of a 2-7GeV Super Tau Charm Facility at China

76

Q. Luo
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Funding: Work supported by National Natural Science Foundation of China U1832169 and the Fundamental Research Funds for the Central Univer-sities, Grant No WK2310000046
As the most successful tau-charm factory of the world, BEPC II will celebrate its 10th birthday this year and will finish its historical mission in the next decade. Because of its very important role in high energy phys-ics study, BEPC II will certainly need a successor, a new tau-charm collider. This paper discusses the feasi-bility of a greenfield next generation tau-charm collid-er named HIEPA. The luminosity of this successor is about 5×10³⁴ cm−2s−1 pilot and 1×1035cm^-2s⁻¹ nominal, with the electron beam longitudinally polarized at the IP. The general scheme of the accelerators and the beam parameters are shown. Several key technologies such as beam polarization and beam emittance diag-nostics are also discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUOBB03

About •

paper received ※ 16 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)