SuperKEKB is an electron–positron asymmetric-energy double-ring collider, which was built in Japan. It has been operated to explore new phenomena in B-meson decays. Hence, extremely higher luminosity ...is required. A collision scheme of low emittance with a large Piwinski angle called a “nano-beam scheme” has been adopted to achieve higher luminosity by squeezing the vertical beta function at the interaction point to be smaller than the bunch length. A “crab waist collision scheme” proposed by P. Raimondi et al. has also been adopted to improve the luminosity performance. The article presents an overview of the operation of the nano-beam and crab waist collision schemes at SuperKEKB.
Summary
Introduction: T‐helper cell type 1 (Th1) polarization of the immune response has been documented in patients with chronic immune thrombocytopenia (ITP). Interleukin (IL)‐10 is the most ...important factor regulating Th1 and T‐helper type 2 cytokine synthesis. This study evaluated the impact of IL‐10 polymorphisms on both susceptibility to, and severity of, chronic ITP.
Methods: We analyzed ‐1082(G/A), ‐812(C/T), and ‐592(C/A) IL‐10 polymorphisms in 90 patients with adult chronic ITP and 202 race‐ and sex‐matched healthy controls.
Results: No significant differences in the genotype or haplotype frequencies were observed between the patient with chronic ITP and the control group. However, more patients with the ‐592AA genotype showed a severe thrombocytopenic state (platelet count <10 × 109/l) than those with the ‐592CC/CA genotypes (44.1%vs. 19.6%, P = 0.01). Furthermore, more patients with the ATA/ATA haplotype showed a severe thrombocytopenic state than those without the ATA/ATA haplotype (44.1%vs. 19.6%, P = 0.01).
Conclusion: According to our data, patients with low producer type of IL‐10 polymorphisms have more severe thrombocytopenia, suggesting that IL‐10 gene polymorphisms may reflect the severity of ITP.
Measurement of chromatic X − Y coupling Ohnishi, Y.; Ohmi, K.; Koiso, H. ...
Physical review special topics. PRST-AB. Accelerators and beams,
09/2009, Volume:
12, Issue:
9
Journal Article
Peer reviewed
Open access
We have measured and corrected chromatic X−Y coupling at an interaction point to improve the luminosity of KEKB. We have measured the beam position of betatron oscillations induced by the kicker ...using turn-by-turn beam position monitors. A phase space structure reconstructed by the beam position provides us not only the Twiss parameters but also information regarding X−Y coupling. We have also determined chromatic X−Y coupling using the measured X−Y coupling at each momentum deviation from the designed beam energy. Skew sextupole magnets are used to correct the chromatic X−Y coupling.
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Optics parameters such as betatron tunes, beta functions, and dispersions depend on momentum deviation. Such dependence is characterized by general chromaticity. General chromaticity can induce ...emittance growth and luminosity degradation in colliders. To investigate the influence of general chromaticity on beam dynamics, a symplectic map for chromaticity was implemented in the beam-beam codes and used in simulations at KEKB. A systematic investigation revealed that chromatic X−Y couplings can deteriorate the machine luminosity in the order of 10% with head-on colliding beams. The results of this study triggered the installation of skew sextupoles to KEKB rings for the purpose of correcting the chromatic X−Y couplings. Beam commissioning with skew-sextupole tuning knobs at KEKB has proved to be very successful; a new world’s record luminosity of 2.1×1034cm−2s−1 was achieved with Belle taking data in June, 2009. In this paper, we discuss the approach of general chromaticity and present the results of simulations at KEKB.
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An orbit feedback system around the interaction point (IP) has been developed and successfully employed at KEKB for more than 6 years. The purpose of the system is to maintain an optimum geometrical ...relationship of orbits of two beams at the IP and to prevent a luminosity degradation due to orbit drifts. The feedback system is based on orbit measurements around the IP rather than a direct measurement of the luminosity. Owing to the system, the luminosity degradation due to the orbit drifts is suppressed to around or less than 1%.
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SuperKEKB beam final focus superconducting magnet system Ohuchi, N.; Arimoto, Y.; Akai, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2022, Volume:
1021
Journal Article
Peer reviewed
Open access
The SuperKEKB was designed and constructed as the upgraded accelerator of KEKB. In this accelerator design, the nano-beam scheme of collision was applied and a luminosity of 8 × 1035 cm−2s−1 was ...targeted. In the design, the beam final focus system was the key component in the accelerator hardware elements. This final focus system consists of 55 superconducting magnets. In this paper, the designs of the magnets, the cryostats and the cryogenic system are shown, and the field measurement results are reported. The SuperKEKB beam operation with the final focus system started on 2018 March 19, and the magnet quench events up to 2020 December 16 are described.
Commissioning of KEKB Akai, K.; Akasaka, N.; Enomoto, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2003, Volume:
499, Issue:
1
Journal Article
Peer reviewed
KEKB has been operated since December, 1998, to deliver
B
B
̄
pairs for a physics detector. In this paper,we describe the commissioning procedure of KEKB.
The KEKB injector linac Abe, I; Akasaka, N; Akemoto, M ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2003, Volume:
499, Issue:
1
Journal Article
Peer reviewed
An 8-GeV electron/3.5-GeV positron injector for KEKB was completed in 1998 by upgrading the existing 2.5-GeV electron/positron linac. The main goals were to upgrade its accelerating energy from 2.5 ...to
8
GeV
and to increase the positron intensity by about 20 times. This article describes not only the composition and features of the upgraded linac, but also how these goals were achieved, by focusing on an optics design and commissioning issues concerning especially high-intensity single-bunch acceleration to produce positron beams.
SuperKEKB beam final focus superconducting magnet system Ohuchi, N.; Arimoto, Y.; Akai, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2021, Volume:
1021
Journal Article
Peer reviewed
Open access
The SuperKEKB was designed and constructed as the upgraded accelerator of KEKB. In this accelerator design, the nano-beam scheme of collision was applied and a luminosity of 8 x1035 cm-2s-1 was ...targeted. In the design, the beam final focus system was the key component in the accelerator hardware elements. This final focus system consists of 55 superconducting magnets. In this paper, the designs of the magnets, the cryostats and the cryogenic system are shown, and the field measurement results are reported. The SuperKEKB beam operation with the final focus system started on 2018 March 19, and the magnet quench events up to 2020 December 16 are described.
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