IBIC2023 - List of Authors (Ikeda, H.)

Paper	Title	Page
TUP002	Development of Bunch Position Monitors to Observe Sudden Beam Loss of SuperKEKB Rings	179
	M. Tobiyama, H. Ikeda, G. Mitsuka KEK, Ibaraki, Japan
	In the SuperKEKB rings, we have encountered extremely-fast beam losses occurring primarily within one to two turns in some parts of the bunch train. Such ¿sudden beam loss¿ induced severe failure in the vertical collimator heads, quenches on the superconducting final quadrupoles, and damage on the Belle II detector in some cases. Thus it is essential to investigate the cause and take countermeasures. This paper presents the phenomena clarified by the bunch current and position monitor of the bunch feedback system. The upgrade plan for the existing monitor, and recently developed simple monitors installed in the suspected area is also introduced.
	Poster TUP002 [0.727 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP002
About •	Received ※ 06 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 27 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP005	Effect of Incoherent Depth of Field for Bean Halo Measurement with the Coronagraph in SuperKEKB	335
	T.M. Mitsuhashi, H. Ikeda, G. Mitsuka KEK, Ibaraki, Japan
	The incoherent depth-of-field due to the instantaneous opening angle of dipole SR will reduce the spatial coherence of SR in horizontal direction in the beam size measurement by using interferometry. This reduction of spatial coherence is due to both of apparent change of the beam profile due to field depth and intensity distribution in the aperture. In the case of beam profile measurement by imaging system, observed beam profile will deform and produce a beam tail in asymmetric manner by this effect. This apparent change of beam profile, especially extra beam tail in one side has certain influence for beam halo measurement using the coronagraph, because it has a large dynamic range of 6 order magnitude. Since the magnitude of asymmetric tail is proportional to bending radius, this effect is larger in large high energy physics machine which has a long bending radius. This effect is theoretically studied and compare with coronagraph measurement result of beam halo in the SuperKEKB. As a conclusion, this effect is very small and not observable in the coronagraph measurement at SuperKEKB.
	Poster WEP005 [0.570 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP005
About •	Received ※ 05 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 21 September 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Development of Bunch Position Monitors to Observe Sudden Beam Loss of SuperKEKB Rings

179

M. Tobiyama, H. Ikeda, G. Mitsuka
KEK, Ibaraki, Japan

In the SuperKEKB rings, we have encountered extremely-fast beam losses occurring primarily within one to two turns in some parts of the bunch train. Such ¿sudden beam loss¿ induced severe failure in the vertical collimator heads, quenches on the superconducting final quadrupoles, and damage on the Belle II detector in some cases. Thus it is essential to investigate the cause and take countermeasures. This paper presents the phenomena clarified by the bunch current and position monitor of the bunch feedback system. The upgrade plan for the existing monitor, and recently developed simple monitors installed in the suspected area is also introduced.

Poster TUP002 [0.727 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP002

About •

Received ※ 06 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 27 September 2023

Cite •

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

WEP005

Effect of Incoherent Depth of Field for Bean Halo Measurement with the Coronagraph in SuperKEKB

335

T.M. Mitsuhashi, H. Ikeda, G. Mitsuka
KEK, Ibaraki, Japan

The incoherent depth-of-field due to the instantaneous opening angle of dipole SR will reduce the spatial coherence of SR in horizontal direction in the beam size measurement by using interferometry. This reduction of spatial coherence is due to both of apparent change of the beam profile due to field depth and intensity distribution in the aperture. In the case of beam profile measurement by imaging system, observed beam profile will deform and produce a beam tail in asymmetric manner by this effect. This apparent change of beam profile, especially extra beam tail in one side has certain influence for beam halo measurement using the coronagraph, because it has a large dynamic range of 6 order magnitude. Since the magnitude of asymmetric tail is proportional to bending radius, this effect is larger in large high energy physics machine which has a long bending radius. This effect is theoretically studied and compare with coronagraph measurement result of beam halo in the SuperKEKB. As a conclusion, this effect is very small and not observable in the coronagraph measurement at SuperKEKB.

Poster WEP005 [0.570 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP005

About •

Received ※ 05 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 21 September 2023

Cite •

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