Test fabrication of a copper beam duct for the KEK B-factory

Suetsugu, Y.; Kanazawa, Kenichi

doi:10.1109/pac.1993.309792

Cited by 3 publications

(3 citation statements)

References 3 publications

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“…To collect an integrated luminosity of 50 ab −1 by the 2030s, our target instantaneous luminosity at 𝛽 * y = 0.3 mm is 6 × 10 35 cm −2 s −1 . Table 8 lists predicted future beam parameters based on the most recent SuperKEKB plan for ramping up the machine [71]. Unfortunately, with the machine lattice considered in the original machine design without the Crab-Waist scheme [6], the target beam currents will be difficult or even impossible to reach because of the short beam lifetime (<10 min) due to the narrow dynamic aperture [72].…”

Section: Extrapolationsmentioning

confidence: 99%

Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider

Natochii

Browder

Cao

et al. 2023

Nuclear Instruments and Methods in Physics Research Section A:

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Section: Extrapolationsmentioning

confidence: 99%

Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider

Natochii

Browder

Cao

et al. 2023

Nuclear Instruments and Methods in Physics Research Section A:

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“…The h value was calculated from the DP/DI value assuming a constant linear pumping speed of 0.03 m 3 s -1 m -1 , which was that after some saturation of NEG (about half of the maximum pumping speed). In the beginning, h was about 1×10 -1 molecules photon -1 and relatively high compared to a typical chemically polished copper duct 21) . The h, however, had decreased steadily with the beam dose, down to less than 5×10 -7 molecules photon -1 at a photon dose of 1×10 26 photons m -1 .…”

Section: Vacuum Propertymentioning

confidence: 85%

Present Status of The KEK B-Factory Vacuum System

Suetsugu

Kanazawa

Kato

et al. 2006

SHINKU

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The KEK B-Factory (KEKB) is a two-ring electron-positron collider with asymmetric energies dedicated to proving the CP violation. The vacuum system has been working satisfactorily form the beginning of commissioning in December, 1998. The maximum stored beam currents are 1.3 A for the 8 GeV electron ring (High Energy Ring, HER), and 1.8 A for the 3.5 GeV positron ring (Low Energy Ring, LER). Most of the beam ducts are made of oxygen-free copper, owing to its ability to withstand an intense heat load and to eŠectively shield the radiation from high beam currents. The pumping scheme is a combination of Non-Evaporable Getter (NEG) pumps and auxiliary sputter ion pumps. An average pressure of about 1×10-7 Pa has been achieved for both rings at the maximum beam currents for both rings. The coe‹cient of photon-stimulated gas desorption has been decreasing steadily to less than 5×10-7 molecules photon-1 at an integrated linear photon density of about 1×10 26 photons m-1. Although special care was taken to make the inside of the beam ducts as smooth as possible in order to avoid the excitation of higher order modes (HOM), the presence of high-current bunched beams has created several problems so far. The intense HOM has sometimes caused the heating of components near to some big HOM sources. Electron cloud around positron bunches led to an instability, which resulted in a vertical beam size blow-up in LER. A discussion about upgrading KEKB has just started aiming at a higher luminosity. The R & D of the vacuum components has also begun based on various experiences so far.

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“…Before To collect an integrated luminosity of 50 ab −1 by the 2030s, our target instantaneous luminosity at β * y = 0.3 mm is 6.3 × 10 35 cm −2 s −1 . Table 8 lists predicted future beam parameters based on the most recent SuperKEKB plan for ramping up the machine [67]. Unfortunately, with the machine lattice considered in the original machine design without the Crab-Waist scheme [4], the target beam currents will be difficult or even impossible to reach because of the short beam lifetime (< 10 min) due to the narrow dynamic aperture [68].…”

Section: Setupmentioning

confidence: 99%

Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider

Natochii¹,

Browder²,

Cao³

et al. 2023

Preprint

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The Belle II experiment at the SuperKEKB electron-positron collider aims to collect an unprecedented data set of 50 ab −1 to study CP-violation in the B-meson system and to search for Physics beyond the Standard Model. SuperKEKB is already the world's highest-luminosity collider. In order to collect the planned data set within approximately one decade, the target is to reach a peak luminosity of 6.3 × 10 35 cm −2 s −1 by further increasing the beam currents and reducing the beam size at the interaction point by squeezing the betatron function down to β * y = 0.3 mm. To ensure detector longevity and maintain good reconstruction performance, beam backgrounds must remain well controlled. We report on current background rates in Belle II and compare these against simulation. We find that a number of recent refinements have significantly improved the background simulation accuracy. Finally, we estimate the safety margins going forward. We predict that backgrounds should remain high but acceptable until a luminosity of at least 2.8 × 10 35 cm −2 s −1 is reached for β * y = 0.6 mm. At this point, the most vulnerable Belle II detectors, the Time-of-Propagation (TOP) particle identification system and the Central Drift Chamber (CDC), have predicted background hit rates from single-beam and luminosity backgrounds that add up to approximately half of the maximum acceptable rates.

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Test fabrication of a copper beam duct for the KEK B-factory

Cited by 3 publications

References 3 publications

Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider

Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider

Present Status of The KEK B-Factory Vacuum System

Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider

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