Experiences at the KEK B-factory vacuum system

Kanazawa, Kenichi; Suetsugu, Y.; Kato, Shigekí; Shibata, K.; Ishibashi, Takuya; Hisamatsu, Hiromi; Shirai, Mitsuru; Shimamoto, Masayuki; Satoh, Masayuki; Nishiwaki, Michiru; Terui, Shinji

doi:10.1093/ptep/pts068

Cited by 7 publications

(6 citation statements)

References 15 publications

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“…I [27]. During the initial stage (D ∼10 19 moleculesphoton −1 ), η (1×10 −2 moleculesphoton −1 ) is several times lower than its value in KEKB (4 × 10 −2 molecules photon −1 ), in which circular Cu beam pipes without any coating were used [7]. At D ¼ 4 × 10 24 photons m −1 , however, η (7 × 10 −6 molecules photon −1 ) has almost the value as in KEKB at the same photon dose.…”

Section: B Vacuum Scrubbingmentioning

confidence: 97%

“…It is interesting to note that η in the HER is lower than that in the HER of KEKB from the beginning [7]. The η at D ¼ 5 × 10 24 photons m −1 (1 × 10 −7 molecules photon −1 ) is much lower than that in the case of KEKB (2 × 10 −6 molecules photon −1 ) at the same D, and its value is almost the same as that in the final stage of KEKB [7].…”

Section: B Vacuum Scrubbingmentioning

confidence: 99%

“…3(a) and 3(b) indicate the NEG conditioning times. Note that the pressures presented here and hereafter are 3 times the values displayed by the vacuum gauges, taking into account the conductance between the beam channels, where the circulating beams pass, and the vacuum gauge ports located above the sputter ion pumps [7].…”

Section: A Operation Summarymentioning

confidence: 99%

“…However, these components were sometimes exposed to air temporarily when broken bellows chambers or ion pumps were replaced with new ones [5]. The MR vacuum system was newly designed based on various experiences with the KEKB vacuum system, and leading-edge concepts were introduced [5][6][7][8]. Beam pipes with antechambers were adopted to reduce the beam impedance and to relax the irradiation power density of the synchrotron radiation (SR) [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: B Vacuum Scrubbingmentioning

confidence: 97%

Section: B Vacuum Scrubbingmentioning

confidence: 99%

Section: A Operation Summarymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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First commissioning of the SuperKEKB vacuum system

Suetsugu

Shibata

Ishibashi

et al. 2016

Phys. Rev. Accel. Beams

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“… 1 高エネルギー加速器研究機構(〒305 0801 茨城県つくば市大穂 1 1) Average photon density 5.3×10 18 6.7×10 18 photons s -1 m -1 Fig. 1 Layout of SuperKEKB at the KEK Tsukuba campus.…”

Section: 平成28年11月29日第57回真空に関する連合講演会で発表unclassified

Vacuum System in the First Operation of SuperKEKB

Suetsugu¹,

Shibata²,

Ishibashi³

et al. 2017

J. Vac. Soc. Jpn.

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First beam loss measurements in the SuperKEKB positron ring using the fast luminosity monitor diamond sensors

Khechen

Funakoshi

Jehanno

et al. 2019

Phys. Rev. Accel. Beams

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SuperKEKB is a very high luminosity e þ e − collider consisting of a low energy ring (LER) of positrons of 4 GeV and a high energy ring (HER) of electrons of 7 GeV. The high luminosity will be achieved thanks to the nanobeam scheme, where very strongly focused beams (σ y ¼ 60 nm) will collide at a large crossing angle of 83 mrad. To maintain high luminosity operation, fast luminosity monitoring is essential in the presence of dynamic instabilities, for feedback and optimization. Fast luminosity monitors consisting of a single crystalline diamond sensor (LAL), a Cherenkov and scintillator detector (KEK) were placed in both rings downstream of the IP (interaction point) to measure the signal from the radiative Bhabha process at zero photon scattering angle (σ ≈ 200 mbarn). During single beam commissioning of SuperKEKB, the fast luminosity monitors were used as beam loss monitors to measure the single beam losses (beam-gas bremsstrahlung, Touschek scattering, Coulomb scattering). In this paper, a detailed description of the experimental setup, the data acquisition scheme, the data analysis and the comparison with the simulation for the diamond sensors, will be reported.

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Experiences at the KEK B-factory vacuum system

Cited by 7 publications

References 15 publications

First commissioning of the SuperKEKB vacuum system

First commissioning of the SuperKEKB vacuum system

Vacuum System in the First Operation of SuperKEKB

First beam loss measurements in the SuperKEKB positron ring using the fast luminosity monitor diamond sensors

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