Recent progress of KEKB

Funakoshi, Y.; Agho, T.; Akai, K.; Ebihara, K.; Egawa, K.; Enomoto, Atsushi; Flanagan, J.; Fukuma, H.; Furukawa, K.; Furuya, T.; Haba, J.; Hiramatsu, S.; Ieiri, T.; Iida, N.; Ikeda, H.; Kageyama, T.; Kamada, S.; Kamitani, T.; Kato, Shigekí; Kikuchi, M.; Kikutani, E.; Koiso, H.; Masuzawa, M.; Mimashi, T.; Morita, Akio; Nakamura, Tatsuro; Nakanishi, Koichi; Nakayama, H.; Ogawa, Y.; Ohmi, K.; Ohnishi, Y.; Ohuchi, N.; Oide, K.; Ono, Masaaki; Shimada, Miho; Suetake, M.; Suetsugu, Y.; Sugimura, T.; Suwada, T.; Tawada, M.; Takeuchi, Masaki; Tobiyama, M.; Tokuda, N.; Uehara, S.; Uno, S.; Yamamoto, Noboru; Yamamoto, Yasuchika; Yano, Yoshiharu; Yokoyama, K.; Yoshida, Masato; Yoshimoto, S.; Zimmermann, Felix

doi:10.1109/pac.2007.4440794

Cited by 5 publications

(4 citation statements)

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“…The KEB collider was a big competitor for PEP-II, with a smaller energy asymmetry. KEKB [4] operated from 1999 to June 2010, reached a peak luminosity more than double with respect to the design value, delivering >1040 fb −1 to Belle. The two rings, crossing with a small horizontal crossing angle of 22 mrad, were completely new, and the design beam parameters were pushed in order to achieve an unprecedented luminosity of 10 34 cm -2 s -1 .…”

Section: Past Colliders: B-factories Pep-ii Kekbmentioning

confidence: 96%

Status and Perspectives of High Luminosity Flavour Factories

Biagini¹

2014

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP 2013)

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The quest for high precision measurements in rare flavor decays requires dedicated colliders with very high peak luminosity and high operation reliability, in order to collect the huge amount of data needed. In the past such Factories were in operation at SLAC (USA) and KEK (Japan) for the study of the B mesons decays, and are still collecting data at IHEP (China) at the Tau/charm energy and at LNF (Italy) and BINP (Russia) at the Φ resonance. Future projects, such as SuperKEKB in Japan, already in the assembly phase, and Tau/charm colliders proposals at BINP and LNF, will deal with a different frontier of experimental subnuclear physics, with a research program complementary to CERN's LHC, by increasing the rate of particle beam collisions at a level that has never been reached before, producing extremely rare physical events which are influenced by the potential existence of new massive particles and thus provide unique information on them. A status of the present facilities and future projects in the "low energy, high luminosity" region will be presented.

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Section: Past Colliders: B-factories Pep-ii Kekbmentioning

confidence: 96%

Status and Perspectives of High Luminosity Flavour Factories

Biagini¹

2014

Proceedings of the European Physical Society Conference on High Energy Physics — PoS(EPS-HEP 2013)

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“…Approximately 90% of the beam pipes in the ring possessed antechambers and the TiN film coating. B z values of up to several millitesla [14,19,50,[56][57][58] were applied by solenoids to the beam pipes in the drift spaces between electromagnets, such as quadrupole or bending magnets, in the ring. In Table I, the circles indicate the countermeasures applied in each major section.…”

Section: Lengthmentioning

confidence: 99%

“…For the beam pipes that had been used since the KEKB era, where the solenoids were already wound, the solenoids were revived, as shown in Fig. 9 [50,57,58]. The magnetic fields generated by these type-1 and type-2 units for the beam pipes are not uniform in the beam direction, as indicated in Figs.…”

Section: Additional Countermeasuresmentioning

confidence: 99%

Mitigating the electron cloud effect in the SuperKEKB positron ring

Suetsugu

Fukuma

Ohmi

et al. 2019

Phys. Rev. Accel. Beams

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SuperKEKB is an electron-positron collider with asymmetric energies located at the High Energy Accelerator Research Organization (KEK) in Tsukuba, Japan. After more than five years of upgrading work on KEKB, phase-1 commissioning commenced in February 2016 and ended in June of the same year. Following a 20-month shutdown for the installation of a particle detector, BELLE II, phase-2 commissioning commenced in March 2018 and ended in July of the same year. This paper describes one major issue faced by SuperKEKB: the electron cloud effect (ECE) in the positron ring, which was observed during phase-1 commissioning. In the high-beam-current region, electron clouds, i.e., the source of the ECE, existed in the beam pipes at drift spaces of the ring, which had antechambers and a titanium nitride (TiN) film coating as countermeasures against the ECE. Permanent magnets and solenoids used to generate magnetic fields in the beam direction were attached to the beam pipes as additional countermeasures before the next commissioning phase commenced. Consequently, during phase-2 commissioning, experiments showed that the threshold of the current linear density for exciting the ECE increased by a factor of at least 2 compared to that during phase-1 commissioning. While the countermeasures were strengthened, the effectiveness of the antechambers and TiN film coating of the real beam pipe was reevaluated. Through various simulations and dedicated experiments during phase-2 commissioning, the antechambers were found to be less effective than anticipated with regard to reducing the number of photoelectrons in the beam channel. In contrast, the TiN film coating had a low secondary electron yield, as expected.

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“…Furthermore, longitudinal grooves and clearing electrodes were prepared in the dipole magnets and wiggler magnets, respectively [29][30][31][32][33][34]. Axial magnetic fields (solenoidal magnetic fields) will be applied along the beam pipes in the drift spaces in the future [35][36][37], but these were not prepared for the first (Phase-1) commissioning.…”

Section: Introductionmentioning

confidence: 99%

First commissioning of the SuperKEKB vacuum system

Suetsugu

Shibata

Ishibashi

et al. 2016

Phys. Rev. Accel. Beams

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The first (Phase-1) commissioning of SuperKEKB, an asymmetric-energy electron-positron collider at KEK, began in February 2016, after more than five years of upgradation work on KEKB and successfully ended in June 2016. A major task of the Phase-1 commissioning was the vacuum scrubbing of new beam pipes in anticipation of a sufficiently long beam lifetime and low background noise in the next commissioning, prior to which a new particle detector will be installed. The pressure rise per unit beam current decreased steadily with increasing beam dose, as expected. Another important task was to check the stabilities of various new vacuum components at high beam currents of approximately 1 A. The temperature increases of the bellows chambers, gate valves, connection flanges, and so on were less than several degrees at 1 A, and no serious problems were found. The effectiveness of the antechambers and TiN coating in suppressing the electron-cloud effect (ECE) in the positron ring was also confirmed. However, the ECE in the Al-alloy bellows chambers was observed where TiN had not been coated. The use of permanent magnets to create an axial magnetic field of approximately 100 G successfully suppressed this effect. Pressure bursts accompanying beam losses were also frequently observed in the positron ring. This phenomenon is still under investigation, but it is likely caused by collisions between the circulating beams and dust particles, especially in the dipole magnet beam pipes.

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Recent progress of KEKB

Cited by 5 publications

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Status and Perspectives of High Luminosity Flavour Factories

Status and Perspectives of High Luminosity Flavour Factories

Mitigating the electron cloud effect in the SuperKEKB positron ring

First commissioning of the SuperKEKB vacuum system

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