eeFACT2018 - List of Authors (Suetsugu, Y.)

Paper	Title	Page
TUYAA04	Study to Mitigate Electron Cloud Effect in SuperKEKB	95
	Y. Suetsugu, H. Fukuma, K. Ohmi, K. Shibata, M. Tobiyama KEK, Ibaraki, Japan
	During Phase-1 commissioning of the SuperKEKB from February to June 2016, electron cloud effects (ECE) were observed in the positron ring. The electron clouds were considered to exist in the beam pipes in the drift spaces of the ring, where the beam pipes have antechambers and titanium nitride (TiN) coating as countermeasures against ECE. Following this, permanent magnets and solenoids were attached to the beam pipes as additional countermeasures. Consequently, during Phase-2 commissioning from March to July 2018, experiments showed that the threshold beam current for exciting ECE increased by a factor of at least two relative to that during Phase-1 commissioning. While the countermeasures were strengthened, the effectiveness of the antechambers and TiN film coating was re-evaluated. From various simulations and experiments during Phase-2 commissioning, the antechamber was found to be less effective than expected with regard to reducing the number of photoelectrons in the beam channel. The TiN film coating, on the other hand, was considered to have a low secondary electron yield as expected.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA04
About •	paper received ※ 27 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)

WEOAB01	Commissioning Status of SuperKEKB Vacuum System	226
	K. Shibata, H. Hisamatsu, T. Ishibashi, K. Kanazawa, M. Shirai, Y. Suetsugu, S. Terui KEK, Ibaraki, Japan
	In the upgrade from the KEKB to the SuperKEKB, approximately 93% and 20% of the beam pipes and vacuum components of the positron ring and the electron ring were replaced with new ones. In the Phase-1 commissioning in 2016, vacuum scrubbing and confirmation of the stabilities of new vacuum components at approximately 1 A were carried out. Though some problems such as pressure bursts accompanying beam losses were revealed, no serious problem was found in the vacuum system. During the subsequent shutdown, the countermeasures against the problems were taken, and new beam pipes and components such as beam collimators were installed. The Phase-2 commissioning, where beam collision tuning was mainly performed, was carried out from March to July 2018. The collimators worked very well to suppress the background noise of the Belle-II detector, though some of them were damaged by the beam. The frequency of the pressure burst drastically decreased though the typical beam currents were lower than those of the Phase-1. The vacuum system of the SuperKEKB has been working generally well so far. The total beam doses of the SuperKEKB exceeded 1000 Ah, and the pressures decreased as expected.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEOAB01
About •	paper received ※ 02 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)

Paper

Title

Page

Study to Mitigate Electron Cloud Effect in SuperKEKB

95

Y. Suetsugu, H. Fukuma, K. Ohmi, K. Shibata, M. Tobiyama
KEK, Ibaraki, Japan

During Phase-1 commissioning of the SuperKEKB from February to June 2016, electron cloud effects (ECE) were observed in the positron ring. The electron clouds were considered to exist in the beam pipes in the drift spaces of the ring, where the beam pipes have antechambers and titanium nitride (TiN) coating as countermeasures against ECE. Following this, permanent magnets and solenoids were attached to the beam pipes as additional countermeasures. Consequently, during Phase-2 commissioning from March to July 2018, experiments showed that the threshold beam current for exciting ECE increased by a factor of at least two relative to that during Phase-1 commissioning. While the countermeasures were strengthened, the effectiveness of the antechambers and TiN film coating was re-evaluated. From various simulations and experiments during Phase-2 commissioning, the antechamber was found to be less effective than expected with regard to reducing the number of photoelectrons in the beam channel. The TiN film coating, on the other hand, was considered to have a low secondary electron yield as expected.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA04

About •

paper received ※ 27 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)

WEOAB01

Commissioning Status of SuperKEKB Vacuum System

226

K. Shibata, H. Hisamatsu, T. Ishibashi, K. Kanazawa, M. Shirai, Y. Suetsugu, S. Terui
KEK, Ibaraki, Japan

In the upgrade from the KEKB to the SuperKEKB, approximately 93% and 20% of the beam pipes and vacuum components of the positron ring and the electron ring were replaced with new ones. In the Phase-1 commissioning in 2016, vacuum scrubbing and confirmation of the stabilities of new vacuum components at approximately 1 A were carried out. Though some problems such as pressure bursts accompanying beam losses were revealed, no serious problem was found in the vacuum system. During the subsequent shutdown, the countermeasures against the problems were taken, and new beam pipes and components such as beam collimators were installed. The Phase-2 commissioning, where beam collision tuning was mainly performed, was carried out from March to July 2018. The collimators worked very well to suppress the background noise of the Belle-II detector, though some of them were damaged by the beam. The frequency of the pressure burst drastically decreased though the typical beam currents were lower than those of the Phase-1. The vacuum system of the SuperKEKB has been working generally well so far. The total beam doses of the SuperKEKB exceeded 1000 Ah, and the pressures decreased as expected.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-WEOAB01

About •

paper received ※ 02 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)